BRIEFER COURSE

BY WILLIAM JAMES
Professor of Psychology in Harvard University


London
MACMILLAN AND CO.
1892

Copyright, 1892,
BY
HENRY HOLT & CO.

Robert Drummond,
Electrotyper and Printer,
New York.

{iii}

In preparing the following abridgment of my larger work, the Principles of Psychology, my chief aim has been to make it more directly available for class-room use. For this purpose I have omitted several whole chapters and rewritten others. I have left out all the polemical and historical matter, all the metaphysical discussions and purely speculative passages, most of the quotations, all the book-references, and (I trust) all the impertinences, of the larger work, leaving to the teacher the choice of orally restoring as much of this material as may seem to him good, along with his own remarks on the topics successively studied. Knowing how ignorant the average student is of physiology, I have added brief chapters on the various senses. In this shorter work the general point of view, which I have adopted as that of 'natural science,' has, I imagine, gained in clearness by its extrication from so much critical matter and its more simple and dogmatic statement. About two fifths of the volume is either new or rewritten, the rest is 'scissors and paste.' I regret to have been unable to supply chapters on pleasure and pain, æsthetics, and the moral sense. Possibly the defect may be made up in a later edition, if such a thing should ever be demanded.

I cannot forbear taking advantage of this preface to make a statement about the composition of the 'Principles of Psychology.' My critics in the main have been so indulgent that I must cordially thank them; but they have been unanimous in one reproach, namely, that my{iv} order of chapters is planless and unnatural; and in one charitable excuse for this, namely, that the work, being largely a collection of review-articles, could not be expected to show as much system as a treatise cast in a single mould. Both the reproach and the excuse misapprehend the facts of the case. The order of composition is doubtless unshapely, or it would not be found so by so many. But planless it is not, for I deliberately followed what seemed to me a good pedagogic order, in proceeding from the more concrete mental aspects with which we are best acquainted to the so-called elements which we naturally come to know later by way of abstraction. The opposite order, of 'building-up' the mind out of its 'units of composition,' has the merit of expository elegance, and gives a neatly subdivided table of contents; but it often purchases these advantages at the cost of reality and truth. I admit that my 'synthetic' order was stumblingly carried out; but this again was in consequence of what I thought were pedagogic necessities. On the whole, in spite of my critics, I venture still to think that the 'unsystematic' form charged upon the book is more apparent than profound, and that we really gain a more living understanding of the mind by keeping our attention as long as possible upon our entire conscious states as they are concretely given to us, than by the post-mortem study of their comminuted 'elements.' This last is the study of artificial abstractions, not of natural things.[1]

{v}

But whether the critics are right, or I am, on this first point, the critics are wrong about the relation of the magazine-articles to the book. With a single exception all the chapters were written for the book; and then by an after-thought some of them were sent to magazines, because the completion of the whole work seemed so distant. My lack of capacity has doubtless been great, but the charge of not having taken the utmost pains, according to my lights, in the composition of the volumes, cannot justly be laid at my door.

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{1}

The definition of Psychology may be best given in the words of Professor Ladd, as the description and explanation of states of consciousness as such. By states of consciousness are meant such things as sensations, desires, emotions, cognitions, reasonings, decisions, volitions, and the like. Their 'explanation' must of course include the study of their causes, conditions, and immediate consequences, so far as these can be ascertained.

Psychology is to be treated as a natural science in this book. This requires a word of commentary. Most thinkers have a faith that at bottom there is but one Science of all things, and that until all is known, no one thing can be completely known. Such a science, if realized, would be Philosophy. Meanwhile it is far from being realized; and instead of it, we have a lot of beginnings of knowledge made in different places, and kept separate from each other merely for practical convenience' sake, until with later growth they may run into one body of Truth. These provisional beginnings of learning we call 'the Sciences' in the plural. In order not to be unwieldy, every such science has to stick to its own arbitrarily-selected problems, and to ignore all others. Every science thus accepts certain data unquestioningly, leaving it to the other parts of Philosophy{2} to scrutinize their significance and truth. All the natural sciences, for example, in spite of the fact that farther reflection leads to Idealism, assume that a world of matter exists altogether independently of the perceiving mind. Mechanical Science assumes this matter to have 'mass' and to exert 'force,' defining these terms merely phenomenally, and not troubling itself about certain unintelligibilities which they present on nearer reflection. Motion similarly is assumed by mechanical science to exist independently of the mind, in spite of the difficulties involved in the assumption. So Physics assumes atoms, action at a distance, etc., uncritically; Chemistry uncritically adopts all the data of Physics; and Physiology adopts those of Chemistry. Psychology as a natural science deals with things in the same partial and provisional way. In addition to the 'material world' with all its determinations, which the other sciences of nature assume, she assumes additional data peculiarly her own, and leaves it to more developed parts of Philosophy to test their ulterior significance and truth. These data are—

1. Thoughts and feelings, or whatever other names transitory states of consciousness may be known by.

2. Knowledge, by these states of consciousness, of other things. These things may be material objects and events, or other states of mind. The material objects may be either near or distant in time and space, and the states of mind may be those of other people, or of the thinker himself at some other time.

How one thing can know another is the problem of what is called the Theory of Knowledge. How such a thing as a 'state of mind' can be at all is the problem of what has been called Rational, as distinguished from Empirical, Psychology. The full truth about states of mind cannot be known until both Theory of Knowledge and Rational Psychology have said their say. Meanwhile an immense amount of provisional truth about them can be got together, which will work in with the larger truth and be{3} interpreted by it when the proper time arrives. Such a provisional body of propositions about states of mind, and about the cognitions which they enjoy, is what I mean by Psychology considered as a natural science. On any ulterior theory of matter, mind, and knowledge, the facts and laws of Psychology thus understood will have their value. If critics find that this natural-science point of view cuts things too arbitrarily short, they must not blame the book which confines itself to that point of view; rather must they go on themselves to complete it by their deeper thought. Incomplete statements are often practically necessary. To go beyond the usual 'scientific' assumptions in the present case, would require, not a volume, but a shelfful of volumes, and by the present author such a shelfful could not be written at all.

Let it also be added that the human mind is all that can be touched upon in this book. Although the mental life of lower creatures has been examined into of late years with some success, we have no space for its consideration here, and can only allude to its manifestations incidentally when they throw light upon our own.

Mental facts cannot be properly studied apart from the physical environment of which they take cognizance. The great fault of the older rational psychology was to set up the soul as an absolute spiritual being with certain faculties of its own by which the several activities of remembering, imagining, reasoning, willing, etc., were explained, almost without reference to the peculiarities of the world with which these activities deal. But the richer insight of modern days perceives that our inner faculties are adapted in advance to the features of the world in which we dwell, adapted, I mean, so as to secure our safety and prosperity in its midst. Not only are our capacities for forming new habits, for remembering sequences, and for abstracting general properties from things and associating their usual consequences with them, exactly the faculties needed for steering us in this world of mixed variety and uniformity, but our emotions{4} and instincts are adapted to very special features of that world. In the main, if a phenomenon is important for our welfare, it interests and excites us the first time we come into its presence. Dangerous things fill us with involuntary fear; poisonous things with distaste; indispensable things with appetite. Mind and world in short have been evolved together, and in consequence are something of a mutual fit. The special interactions between the outer order and the order of consciousness, by which this harmony, such as it is, may in the course of time have come about, have been made the subject of many evolutionary speculations, which, though they cannot so far be said to be conclusive, have at least refreshed and enriched the whole subject, and brought all sorts of new questions to the light.

The chief result of all this more modern view is the gradually growing conviction that mental life is primarily teleological; that is to say, that our various ways of feeling and thinking have grown to be what they are because of their utility in shaping our reactions on the outer world. On the whole, few recent formulas have done more service in psychology than the Spencerian one that the essence of mental life and bodily life are one, namely, 'the adjustment of inner to outer relations.' The adjustment is to immediately present objects in lower animals and in infants. It is to objects more and more remote in time and space, and inferred by means of more and more complex and exact processes of reasoning, when the grade of mental development grows more advanced.

Primarily then, and fundamentally, the mental life is for the sake of action of a preservative sort. Secondarily and incidentally it does many other things, and may even, when ill 'adapted,' lead to its possessor's destruction. Psychology, taken in the widest way, ought to study every sort of mental activity, the useless and harmful sorts as well as that which is 'adapted.' But the study of the harmful in mental life has been made the subject of a special branch called 'Psychiatry'—the science of insanity—and{5} the study of the useless is made over to 'Æsthetics.' Æsthetics and Psychiatry will receive no special notice in this book.

All mental states (no matter what their character as regards utility may be) are followed by bodily activity of some sort. They lead to inconspicuous changes in breathing, circulation, general muscular tension, and glandular or other visceral activity, even if they do not lead to conspicuous movements of the muscles of voluntary life. Not only certain particular states of mind, then (such as those called volitions, for example), but states of mind as such, all states of mind, even mere thoughts and feelings, are motor in their consequences. This will be made manifest in detail as our study advances. Meanwhile let it be set down as one of the fundamental facts of the science with which we are engaged.

It was said above that the 'conditions' of states of consciousness must be studied. The immediate condition of a state of consciousness is an activity of some sort in the cerebral hemispheres. This proposition is supported by so many pathological facts, and laid by physiologists at the base of so many of their reasonings, that to the medically educated mind it seems almost axiomatic. It would be hard, however, to give any short and peremptory proof of the unconditional dependence of mental action upon neural change. That a general and usual amount of dependence exists cannot possibly be ignored. One has only to consider how quickly consciousness may be (so far as we know) abolished by a blow on the head, by rapid loss of blood, by an epileptic discharge, by a full dose of alcohol, opium, ether, or nitrous oxide—or how easily it may be altered in quality by a smaller dose of any of these agents or of others, or by a fever,—to see how at the mercy of bodily happenings our spirit is. A little stoppage of the gall-duct, a swallow of cathartic medicine, a cup of strong coffee at the proper moment, will entirely overturn for the time a man's views of life. Our moods and resolutions are more determined{6} by the condition of our circulation than by our logical grounds. Whether a man shall be a hero or a coward is a matter of his temporary 'nerves.' In many kinds of insanity, though by no means in all, distinct alterations of the brain-tissue have been found. Destruction of certain definite portions of the cerebral hemispheres involves losses of memory and of acquired motor faculty of quite determinate sorts, to which we shall revert again under the title of aphasias. Taking all such facts together, the simple and radical conception dawns upon the mind that mental action may be uniformly and absolutely a function of brain-action, varying as the latter varies, and being to the brain-action as effect to cause.

This conception is the 'working hypothesis' which underlies all the 'physiological psychology' of recent years, and it will be the working hypothesis of this book. Taken thus absolutely, it may possibly be too sweeping a statement of what in reality is only a partial truth. But the only way to make sure of its unsatisfactoriness is to apply it seriously to every possible case that can turn up. To work an hypothesis 'for all it is worth' is the real, and often the only, way to prove its insufficiency. I shall therefore assume without scruple at the outset that the uniform correlation of brain-states with mind-states is a law of nature. The interpretation of the law in detail will best show where its facilities and where its difficulties lie. To some readers such an assumption will seem like the most unjustifiable a priori materialism. In one sense it doubtless is materialism: it puts the Higher at the mercy of the Lower. But although we affirm that the coming to pass of thought is a consequence of mechanical laws,—for, according to another 'working hypothesis,' that namely of physiology, the laws of brain-action are at bottom mechanical laws,—we do not in the least explain the nature of thought by affirming this dependence, and in that latter sense our proposition is not materialism. The authors who most unconditionally affirm the dependence of our thoughts{7} on our brain to be a fact are often the loudest to insist that the fact is inexplicable, and that the intimate essence of consciousness can never be rationally accounted for by any material cause. It will doubtless take several generations of psychologists to test the hypothesis of dependence with anything like minuteness. The books which postulate it will be to some extent on conjectural ground. But the student will remember that the Sciences constantly have to take these risks, and habitually advance by zig—zagging from one absolute formula to another which corrects it by going too far the other way. At present Psychology is on the materialistic tack, and ought in the interests of ultimate success to be allowed full headway even by those who are certain she will never fetch the port without putting down the helm once more. The only thing that is perfectly certain is that when taken up into the total body of Philosophy, the formulas of Psychology will appear with a very different meaning from that which they suggest so long as they are studied from the point of view of an abstract and truncated 'natural science,' however practically necessary and indispensable their study from such a provisional point of view may be.

The Divisions of Psychology.—So far as possible, then, we are to study states of consciousness in correlation with their probable neural conditions. Now the nervous system is well understood to-day to be nothing but a machine for receiving impressions and discharging reactions preservative to the individual and his kind—so much of physiology the reader will surely know. Anatomically, therefore, the nervous system falls into three main divisions, comprising—

Functionally, we have sensation, central reflection, and motion, to correspond to these anatomical divisions. In Psychology we may divide our work according to a similar{8} scheme, and treat successively of three fundamental conscious processes and their conditions. The first will be Sensation; the second will be Cerebration or Intellection; the third will be the Tendency to Action. Much vagueness results from this division, but it has practical conveniences for such a book as this, and they may be allowed to prevail over whatever objections may be urged.{9}

Incoming nerve-currents are the only agents which normally affect the brain. The human nerve-centres are surrounded by many dense wrappings of which the effect is to protect them from the direct action of the forces of the outer world. The hair, the thick skin of the scalp, the skull, and two membranes at least, one of them a tough one, surround the brain; and this organ moreover, like the spinal cord, is bathed by a serous fluid in which it floats suspended. Under these circumstances the only things that can happen to the brain are:

1) The dullest and feeblest mechanical jars;

2) Changes in the quantity and quality of the blood-supply; and

3) Currents running in through the so-called afferent or centripetal nerves.

The mechanical jars are usually ineffective; the effects of the blood-changes are usually transient; the nerve-currents, on the contrary, produce consequences of the most vital sort, both at the moment of their arrival, and later, through the invisible paths of escape which they plough in the substance of the organ and which, as we believe, remain as more or less permanent features of its structure, modifying its action throughout all future time.{10}

Each afferent nerve comes from a determinate part of the periphery and is played upon and excited to its inward activity by a particular force of the outer world. Usually it is insensible to other forces: thus the optic nerves are not impressible by air-waves, nor those of the skin by light-waves. The lingual nerve is not excited by aromatic effluvia, the auditory nerve is unaffected by heat. Each selects from the vibrations of the outer world some one rate to which it responds exclusively. The result is that our sensations form a discontinuous series, broken by enormous gaps. There is no reason to suppose that the order of vibrations in the outer world is anything like as interrupted as the order of our sensations. Between the quickest audible air-waves (40,000 vibrations a second at the outside) and the slowest sensible heat-waves (which number probably billions), Nature must somewhere have realized innumerable intermediary rates which we have no nerves for perceiving. The process in the nerve-fibres themselves is very likely the same, or much the same, in all the different nerves. It is the so-called 'current'; but the current is started by one order of outer vibrations in the retina, and in the ear, for example, by another. This is due to the different terminal organs with which the several afferent nerves are armed. Just as we arm ourselves with a spoon to pick up soup, and with a fork to pick up meat, so our nerve-fibres arm themselves with one sort of end-apparatus to pick up air-waves, with another to pick up ether-waves. The terminal apparatus always consists of modified epithelial cells with which the fibre is continuous. The fibre itself is not directly excitable by the outer agent which impresses the terminal organ. The optic fibres are unmoved by the direct rays of the sun; a cutaneous nerve-trunk may be touched with ice without feeling cold.[2] The{11} fibres are mere transmitters; the terminal organs are so many imperfect telephones into which the material world speaks, and each of which takes up but a portion of what it says; the brain-cells at the fibres' central end are as many others at which the mind listens to the far-off call.

The 'Specific Energies' of the Various Parts of the Brain.—To a certain extent anatomists have traced definitely the paths which the sensory nerve-fibres follow after their entrance into the centres, as far as their termination in the gray matter of the cerebral convolutions.[3] It will be shown on a later page that the consciousness which accompanies the excitement of this gray matter varies from one portion of it to another. It is consciousness of things seen, when the occipital lobes, and of things heard, when the upper part of the temporal lobes, share in the excitement. Each region of the cerebral cortex responds to the stimulation which its afferent fibres bring to it, in a manner with which a peculiar quality of feeling seems invariably correlated. This is what has been called the law of 'specific energies' in the nervous system. Of course we are without even a conjectural explanation of the ground of such a law. Psychologists (as Lewes, Wundt, Rosenthal, Goldscheider, etc.) have debated a good deal as to whether the specific quality of the feeling depends solely on the place stimulated in the cortex, or on the sort of current which the nerve pours in. Doubtless the sort of outer force habitually impinging on the end-organ gradually modifies the end-organ, the sort of commotion received from the end-organ modifies the fibre, and the sort of current a so-modified fibre pours into the cortical centre modifies the centre. The modification of the centre in turn (though no man{12} can guess how or why) seems to modify the resultant consciousness. But these adaptive modifications must be excessively slow; and as matters actually stand in any adult individual, it is safe to say that, more than anything else, the place excited in his cortex decides what kind of thing he shall feel. Whether we press the retina, or prick, cut, pinch, or galvanize the living optic nerve, the Subject always feels flashes of light, since the ultimate result of our operations is to stimulate the cortex of his occipital region. Our habitual ways of feeling outer things thus depend on which convolutions happen to be connected with the particular end-organs which those things impress. We see the sunshine and the fire, simply because the only peripheral end-organ susceptible of taking up the ether-waves which these objects radiate excites those particular fibres which run to the centres of sight. If we could interchange the inward connections, we should feel the world in altogether new ways. If, for instance, we could splice the outer extremity of our optic nerves to our ears, and that of our auditory nerves to our eyes, we should hear the lightning and see the thunder, see the symphony and hear the conductor's movements. Such hypotheses as these form a good training for neophytes in the idealistic philosophy!

Sensation distinguished from Perception.—It is impossible rigorously to define a sensation; and in the actual life of consciousness sensations, popularly so called, and perceptions merge into each other by insensible degrees. All we can say is that what we mean by sensations are FIRST things in the way of consciousness. They are the immediate results upon consciousness of nerve-currents as they enter the brain, and before they have awakened any suggestions or associations with past experience. But it is obvious that such immediate sensations can only be realized in the earliest days of life. They are all but impossible to adults with memories and stores of associations acquired. Prior to all impressions on sense-organs, the brain is plunged in deep sleep and consciousness is practically non-existent{13}. Even the first weeks after birth are passed in almost unbroken sleep by human infants. It takes a strong message from the sense-organs to break this slumber. In a new-born brain this gives rise to an absolutely pure sensation. But the experience leaves its 'unimaginable touch' on the matter of the convolutions, and the next impression which a sense-organ transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part. Another sort of feeling and a higher grade of cognition are the consequence. 'Ideas' about the object mingle with the awareness of its mere sensible presence, we name it, class it, compare it, utter propositions concerning it, and the complication of the possible consciousness which an incoming current may arouse, goes on increasing to the end of life. In general, this higher consciousness about things is called Perception, the mere inarticulate feeling of their presence is Sensation, so far as we have it at all. To some degree we seem able to lapse into this inarticulate feeling at moments when our attention is entirely dispersed.

Sensations are cognitive. A sensation is thus an abstraction seldom realized by itself; and the object which a sensation knows is an abstract object which cannot exist alone. 'Sensible qualities' are the objects of sensation. The sensations of the eye are aware of the colors of things, those of the ear are acquainted with their sounds; those of the skin feel their tangible heaviness, sharpness, warmth or coldness, etc., etc. From all the organs of the body currents may come which reveal to us the quality of pain, and to a certain extent that of pleasure.

Such qualities as stickiness, roughness, etc., are supposed to be felt through the coöperation of muscular sensations with those of the skin. The geometrical qualities of things, on the other hand, their shapes, bignesses, distances, etc. (so far as we discriminate and identify them), are by most psychologists supposed to be impossible without the evocation of memories from the past; and the{14} cognition of these attributes is thus considered to exceed the power of sensation pure and simple.

'Knowledge of Acquaintance' and 'Knowledge about.'—Sensation, thus considered, differs from perception only in the extreme simplicity of its object or content. Its object, being a simple quality, is sensibly homogeneous; and its function is that of mere acquaintance with this homogeneous seeming fact. Perception's function, on the other hand, is that of knowing something about the fact. But we must know what fact we mean, all the while, and the various whats are what sensations give. Our earliest thoughts are almost exclusively sensational. They give us a set of whats, or thats, or its; of subjects of discourse in other words, with their relations not yet brought out. The first time we see light, in Condillac's phrase we are it rather than see it. But all our later optical knowledge is about what this experience gives. And though we were struck blind from that first moment, our scholarship in the subject would lack no essential feature so long as our memory remained. In training-institutions for the blind they teach the pupils as much about light as in ordinary schools. Reflection, refraction, the spectrum, the ether-theory, etc., are all studied. But the best taught born-blind pupil of such an establishment yet lacks a knowledge which the least instructed seeing baby has. They can never show him what light is in its 'first intention'; and the loss of that sensible knowledge no book-learning can replace. All this is so obvious that we usually find sensation 'postulated' as an element of experience, even by those philosophers who are least inclined to make much of its importance, or to pay respect to the knowledge which it brings.

Sensations distinguished from Images.—Both sensation and perception, for all their difference, are yet alike in that their objects appear vivid, lively, and present. Objects merely thought of, recollected, or imagined, on the contrary, are relatively faint and devoid of this pungency, or tang, this quality of real presence which the objects of sensation{15} possess. Now the cortical brain-processes to which sensations are attached are due to incoming currents from the periphery of the body—an external object must excite the eye, ear, etc., before the sensation comes. Those cortical processes, on the other hand, to which mere ideas or images are attached are due in all probability to currents from other convolutions. It would seem, then, that the currents from the periphery normally awaken a kind of brain-activity which the currents from other convolutions are inadequate to arouse. To this sort of activity—a profounder degree of disintegration, perhaps—the quality of vividness, presence, or reality in the object of the resultant consciousness seems correlated.

The Exteriority of Objects of Sensation.—Every thing or quality felt is felt in outer space. It is impossible to conceive a brightness or a color otherwise than as extended and outside of the body. Sounds also appear in space. Contacts are against the body's surface; and pains always occupy some organ. An opinion which has had much currency in psychology is that sensible qualities are first apprehended as in the mind itself, and then 'projected' from it, or 'extradited,' by a secondary intellectual or super-sensational mental act. There is no ground whatever for this opinion. The only facts which even seem to make for it can be much better explained in another way, as we shall see later on. The very first sensation which an infant gets is for him the outer universe. And the universe which he comes to know in later life is nothing but an amplification of that first simple germ which, by accretion on the one hand and intussusception on the other, has grown so big and complex and articulate that its first estate is unrememberable. In his dumb awakening to the consciousness of something there, a mere this as yet (or something for which even the term this would perhaps be too discriminative, and the intellectual acknowledgment of which would be better expressed by the bare interjection 'lo!'), the infant encounters an object in which (though it{16} be given in a pure sensation) all the 'categories of the understanding' are contained. It has externality, objectivity, unity, substantiality, causality, in the full sense in which any later object or system of objects has these things. Here the young knower meets and greets his world; and the miracle of knowledge bursts forth, as Voltaire says, as much in the infant's lowest sensation as in the highest achievement of a Newton's brain.

The physiological condition of this first sensible experience is probably many nerve-currents coming in from various peripheral organs at once; but this multitude of organic conditions does not prevent the consciousness from being one consciousness. We shall see as we go on that it can be one consciousness, even though it be due to the coöperation of numerous organs and be a consciousness of many things together. The Object which the numerous inpouring currents of the baby bring to his consciousness is one big blooming buzzing Confusion. That Confusion is the baby's universe; and the universe of all of us is still to a great extent such a Confusion, potentially resolvable, and demanding to be resolved, but not yet actually resolved, into parts. It appears from first to last as a space-occupying thing. So far as it is unanalyzed and unresolved we may be said to know it sensationally; but as fast as parts are distinguished in it and we become aware of their relations, our knowledge becomes perceptual or even conceptual, and as such need not concern us in the present chapter.

The Intensity of Sensations.—A light may be so weak as not sensibly to dispel the darkness, a sound so low as not to be heard, a contact so faint that we fail to notice it. In other words, a certain finite amount of the outward stimulus is required to produce any sensation of its presence at all. This is called by Fechner the law of the threshold—something must be stepped over before the object can gain entrance to the mind. An impression just above the threshold is called the minimum visibile, audibile, etc.{17} From this point onwards, as the impressing force increases, the sensation increases also, though at a slower rate, until at last an acme of the sensation is reached which no increase in the stimulus can make sensibly more great. Usually, before the acme, pain begins to mix with the specific character of the sensation. This is definitely observable in the cases of great pressure, intense heat, cold, light, and sound; and in those of smell and taste less definitely so only from the fact that we can less easily increase the force of the stimuli here. On the other hand, all sensations, however unpleasant when more intense, are rather agreeable than otherwise in their very lowest degrees. A faintly bitter taste, or putrid smell, may at least be interesting.

Weber's Law.—I said that the intensity of the sensation increases by slower steps than those by which its exciting cause increases. If there were no threshold, and if every equal increment in the outer stimulus produced an equal increment in the sensation's intensity, a simple straight line would represent graphically the 'curve' of the relation between the two things. Let the horizontal line stand for the scale of intensities of the objective stimulus, so that at 0 it has no intensity, at 1 intensity 1, and so forth. Let the verticals dropped from the slanting line stand for the sensations aroused. At 0 there will be no sensation; at 1 there will be a sensation represented by the length of the vertical S¹—1, at 2 the sensation will be represented by{18} S²—2, and so on. The line of S's will rise evenly because by the hypothesis the verticals (or sensations) increase at the same rate as the horizontals (or stimuli) to which they severally correspond. But in Nature, as aforesaid, they increase at a slower rate. If each step forward in the horizontal direction be equal to the last, then each step upward in the vertical direction will have to be somewhat shorter than the last; the line of sensations will be convex on top instead of straight.

Fig. 2 represents this actual state of things, 0 being the zero-point of the stimulus, and conscious sensation, represented by the curved line, not beginning until the 'threshold' is reached, at which the stimulus has the value 3. From here onwards the sensation increases, but it increases less at each step, until at last, the 'acme' being reached, the sensation-line grows flat. The exact law of retardation is called Weber's law, from the fact that he first observed it in the case of weights. I will quote Wundt's account of the law and of the facts on which it is based.

Observations according to this method are particularly easy to make in the spheres of light, sound, and pressure. Beginning with the latter case,

Wundt then describes how differences may be observed in the muscular feelings, in the feelings of heat, in those of light, and in those of sound; and he concludes thus:

Fechner's Law.—Another way of expressing Weber's law is to say that to get equal positive additions to the sensation, one must make equal relative additions to the stimulus. Professor Fechner of Leipzig founded upon Weber's law a theory of the numerical measurement of sensations, over which much metaphysical discussion has raged. Each just perceptible addition to the sensation, as we gradually let the stimulus increase, was supposed by him to be a unit of sensation, and all these units were treated by him as equal, in spite of the fact that equally perceptible increments need by no means appear equally big when they once are perceived. The many pounds which form the just perceptible addition to a hundredweight feel bigger when added than the few ounces which form the just perceptible addition to a pound. Fechner ignored this fact. He considered that if n distinct perceptible steps of increase might be passed through in gradually increasing a stimulus from the threshold-value till the intensity s was felt, then the sensation of s was composed of n units, which were of the same value all along the line.[5] Sensations once{22} represented by numbers, psychology may become, according to Fechner, an 'exact' science, susceptible of mathematical treatment. His general formula for getting at the number of units in any sensation is S = C log R, where S stands for the sensation, R for the stimulus numerically estimated, and C for a constant that must be separately determined by experiment in each particular order of sensibility. The sensation is proportional to the logarithm of the stimulus; and the absolute values, in units, of any series of sensations might be got from the ordinates of the curve in Fig. 2, if it were a correctly drawn logarithmic curve, with the thresholds rightly plotted out from experiments.

Fechner's psycho-physic formula, as he called it, has been attacked on every hand; and as absolutely nothing practical has come of it, it need receive no farther notice here. The main outcome of his book has been to stir up experimental investigation into the validity of Weber's law (which concerns itself merely with the just perceptible increase, and says nothing about the measurement of the sensation as a whole) and to promote discussion of statistical methods. Weber's law, as will appear when we take the senses, seriatim, is only approximately verified. The discussion of statistical methods is necessitated by the extraordinary fluctuations of our sensibility from one moment to the next. It is found, namely, when the difference of two sensations approaches the limit of discernibility, that at one moment we discern it and at the next we do not. Our incessant accidental inner alterations make it impossible to tell just what the least discernible increment of the sensation is without taking the average of a large number of appreciations. These accidental errors are as likely to increase as to diminish our sensibility, and are eliminated in such an average, for those above and those below{23} the line then neutralize each other in the sum, and the normal sensibility, if there be one (that is, the sensibility due to constant causes as distinguished from these accidental ones), stands revealed. The methods of getting the average all have their difficulties and their snares, and controversy over them has become very subtle indeed. As an instance of how laborious some of the statistical methods are, and how patient German investigators can be, I may say that Fechner himself, in testing Weber's law for weights by the so-called 'method of true and false cases,' tabulated and computed no less than 24,576 separate judgments.

Sensations are not compounds. The fundamental objection to Fechner's whole attempt seems to be this, that although the outer causes of our sensations may have many parts, every distinguishable degree, as well as every distinguishable quality, of the sensation itself appears to be a unique fact of consciousness. Each sensation is a complete integer. "A strong one," as Dr. Münsterberg says, "is not the multiple of a weak one, or a compound of many weak ones, but rather something entirely new, and as it were incomparable, so that to seek a measurable difference between strong and weak sonorous, luminous, or thermic sensations would seem at first sight as senseless as to try to compute mathematically the difference between salt and sour, or between headache and toothache. It is clear that if in the stronger sensation of light the weaker sensation is not contained, it is unpsychological to say that the former differs from the latter by a certain increment."[6] Surely our feeling of scarlet is not a feeling of pink with a lot more pink added; it is something quite other than pink. Similarly with our sensation of an electric arc-light: it does not contain that of many smoky tallow candles in itself. Every sensation presents itself as an indivisible unit; and it is quite impossible to read any clear meaning into the notion that they are masses of units combined.{24}

There is no inconsistency between this statement and the fact that, starting with a weak sensation and increasing it, we feel 'more,' 'more,' 'more,' as the increase goes on. It is not more of the same stuff added, so to speak; but it is more and more difference, more and more distance, from the starting-point, which we feel. In the chapter on Discrimination we shall see that Difference can be perceived between simple things. We shall see, too, that differences themselves differ—there are various directions of difference; and along any one of them a series of things may be arranged so as to increase steadily in that direction. In any such series the end differs more from the beginning than the middle does. Differences of 'intensity' form one such direction of possible increase—so our judgments of more intensity can be expressed without the hypothesis that more units have been added to a growing sum.

The so-called 'Law of Relativity.'—Weber's law seems only one case of the still wider law that the more we have to attend to the less capable we are of noticing any one detail. The law is obvious where the things differ in kind. How easily do we forget a bodily discomfort when conversation waxes hot; how little do we notice the noises in the room so long as our work absorbs us! Ad plura intentus minus est ad singula sensus, as the old proverb says. One might now add that the homogeneity of what we have to attend to does not alter the result; but that a mind with two strong sensations of the same sort already before it is incapacitated by their amount from noticing the detail of a difference between them which it would immediately be struck by, were the sensations themselves weaker and consequently endowed with less distracting power.

This particular idea may be taken for what it is worth.[7] Meanwhile it is an undoubted general fact that the psychical{25} effect of incoming currents does depend on what other currents may be simultaneously pouring in. Not only the perceptibility of the object which the current brings before the mind, but the quality of it, is changed by the other currents. "Simultaneous[8] sensations modify each other" is a brief expression for this law. "We feel all things in relation to each other" is Wundt's vaguer formula for this general 'law of relativity,' which in one shape or other has had vogue since Hobbes's time in psychology. Much mystery has been made of it, but although we are of course ignorant of the more intimate processes involved, there seems no ground to doubt that they are physiological, and come from the interference of one current with another. A current interfered with might naturally give rise to a modified sensation.

Examples of the modification in question are easy to find.[9] Notes make each other sweeter in a chord, and so do colors when harmoniously combined. A certain amount of skin dipped in hot water gives the perception of a certain heat. More skin immersed makes the heat much more intense, although of course the water's heat is the same. Similarly there is a chromatic minimum of size in objects. The image they cast on the retina must needs excite a sufficient number of fibres, or it will give no sensation of color at all. Weber observed that a thaler laid on the skin of the forehead feels heavier when cold than when warm. Urbantschitsch has found that all our sense-organs influence each other's sensations. The hue of patches of color so distant as not to be recognized was immediately, in his patients, perceived when a tuning-fork was sounded close to the ear. Letters too far off to be read could be read{26} when the tuning-fork was heard, etc., etc. The most familiar examples of this sort of thing seem to be the increase of pain by noise or light, and the increase of nausea by all concomitant sensations.

Effects of Contrast.—The best-known examples of the way in which one nerve-current modifies another are the phenomena of what is known as 'simultaneous color-contrast.' Take a number of sheets of brightly and differently colored papers, lay on each of them a bit of one and the same kind of gray paper, then cover each sheet with some transparent white paper, which softens the look of both the gray paper and the colored ground. The gray patch will appear in each case tinged by the color complementary to the ground; and so different will the several pieces appear that no observer, before raising the transparent paper, will believe them all cut out of the same gray. Helmholtz has interpreted these results as being due to a false application of an inveterate habit—that, namely, of making allowance for the color of the medium through which things are seen. The same thing, in the blue light of a clear sky, in the reddish-yellow light of a candle, in the dark brown light of a polished mahogany table which may reflect its image, is always judged of its own proper color, which the mind adds out of its own knowledge to the appearance, thereby correcting the falsifying medium. In the cases of the papers, according to Helmholtz, the mind believes the color of the ground, subdued by the transparent paper, to be faintly spread over the gray patch. But a patch to look gray through such a colored film would have really to be of the complementary color to the film. Therefore it is of the complementary color, we think, and proceed to see it of that color.

This theory has been shown to be untenable by Hering. The discussion of the facts is too minute for recapitulation here, but suffice it to say that it proves the phenomenon to be physiological—a case of the way in which, when sensory nerve-currents run in together, the effect of each on{27} consciousness is different from that which it would be if they ran in separately.

'Successive contrast' differs from the simultaneous variety, and is supposed to be due to fatigue. The facts will be noticed under the head of 'after-images,' in the section on Vision. It must be borne in mind, however, that after-images from previous sensations may coexist with present sensations, and the two may modify each other just as coexisting sensational processes do.

Other senses than sight show phenomena of contrast, but they are much less obvious, so I will not notice them here. We can now pass to a very brief survey of the various senses in detail.{28}

The Eye's Structure is described in all the books on anatomy. I will only mention the few points which concern the psychologist.[10] It is a flattish sphere formed by a tough{29}

white membrane (the sclerotic), which encloses a nervous surface and certain refracting media (lens and 'humors') which cast a picture of the outer world thereon. It is in{30} fact a little camera obscura, the essential part of which is the sensitive plate.

The retina is what corresponds to this plate. The optic nerve pierces the sclerotic shell and spreads its fibres radially in every direction over its inside, forming a thin translucent film (see Fig. 3, Ret.). The fibres pass into a complicated apparatus of cells, granules, and branches (Fig. 4), and finally end in the so-called rods and cones (Fig. 4,—9), which are the specific organs for taking up the influence of the waves of light. Strange to say, these end-organs are not pointed forward towards the light as it streams through the pupil, but backwards towards the sclerotic membrane itself, so that the light-waves traverse the translucent nerve-fibres, and the cellular and granular layers of the retina, before they touch the rods and cones themselves. (See Fig. 5.){31}

The Blind Spot.—The optic nerve-fibres must thus be unimpressible by light directly. The place where the nerve enters is in fact entirely blind, because nothing but fibres exist there, the other layers of the retina only beginning round about the entrance. Nothing is easier than to prove the existence of this blind spot. Close the right eye and look steadily with the left at the cross in Fig. 6, holding the book vertically in front of the face, and moving it to and fro. It will be found that at about a foot off the black disk disappears; but when the page is nearer or farther, it is seen. During the experiment the gaze must be kept fixed on the cross. It is easy to show by measurement that this blind spot lies where the optic nerve enters.

The Fovea.—Outside of the blind spot the sensibility of the retina varies. It is greatest at the fovea, a little pit lying outwardly from the entrance of the optic nerve, and round which the radiating nerve-fibres bend without passing over it. The other layers also disappear at the fovea, leaving the cones alone to represent the retina there. The sensibility of the retina grows progressively less towards its periphery, by means of which neither colors, shapes, nor number of impressions can be well discriminated.

In the normal use of our two eyes, the eyeballs are rotated so as to cause the two images of any object which catches the attention to fall on the two foveæ, as the spots of acutest vision. This happens involuntarily, as any one may observe. In fact, it is almost impossible not to 'turn the eyes,' the moment any peripherally lying object does catch our attention, the turning of the eyes being only{32} another name for such rotation of the eyeballs as will bring the foveæ under the object's image.

Accommodation.—The focussing or sharpening of the image is performed by a special apparatus. In every camera, the farther the object is from the eye the farther forward, and the nearer the object is to the eye the farther backward, is its image thrown. In photographers' cameras the back is made to slide, and can be drawn away from the lens when the object that casts the picture is near, and pushed forward when it is far. The picture is thus kept always sharp. But no such change of length is possible in the eyeball; and the same result is reached in another way. The lens, namely, grows more convex when a near object is looked at, and flatter when the object recedes. This change is due to the antagonism of the circular 'ligament' in which the lens is suspended, and the 'ciliary muscle.' The ligament, when the ciliary muscle is at rest, assumes such a spread-out shape as to keep the lens rather flat. But the lens is highly elastic; and it springs into the more convex form which is natural to it whenever the ciliary muscle, by contracting, causes the ligament to relax its pressure. The contraction of the muscle, by thus rendering the lens more refractive, adapts the eye for near objects ('accommodates' it for them, as we say); and its relaxation, by rendering the lens less refractive, adapts the eye for distant vision. Accommodation for the near is thus{33} the more active change, since it involves contraction of the ciliary muscle. When we look far off, we simply let our eyes go passive. We feel this difference in the effort when we compare the two sensations of change.

Convergence accompanies accommodation. The two eyes act as one organ; that is, when an object catches the attention, both eyeballs turn so that its images may fall on the foveæ. When the object is near, this naturally requires them to turn inwards, or converge; and as accommodation then also occurs, the two movements of convergence and accommodation form a naturally associated couple, of which it is difficult to execute either singly. Contraction of the pupil also accompanies the accommodative act. When we come to stereoscopic vision, it will appear that by much practice one can learn to converge with relaxed accommodation, and to accommodate with parallel axes of vision. These are accomplishments which the student of psychological optics will find most useful.

Single Vision by the two Retinæ.—We hear single with two ears, and smell single with two nostrils, and we also see single with two eyes. The difference is that we also can see double under certain conditions, whereas under no conditions can we hear or smell double. The main conditions of single vision can be simply expressed.

In the first place, impressions on the two foveæ always appear in the same place. By no artifice can they be made to appear alongside of each other. The result is that one object, casting its images on the foveæ of the two converging eyeballs will necessarily always appear as what it is, namely, one object. Furthermore, if the eyeballs, instead of converging, are kept parallel, and two similar objects, one in front of each, cast their respective images on the foveæ, the two will also appear as one, or (in common parlance) 'their images will fuse.' To verify this, let the reader stare fixedly before him as if through the paper at infinite distance, with the black spots in Fig. 8 in front of his respective eyes. He{34} will then see the two black spots swim together, as it were, and combine into one, which appears situated between their original two positions and as if opposite the root of his nose. This combined spot is the result of the spots opposite both eyes being seen in the same place. But in addition to the combined spot, each eye sees also the spot opposite the other eye. To the right eye this appears to the left of the combined spot, to the left eye it appears to the right of it; so that what is seen is three spots, of which the middle one is seen by both eyes, and is flanked by two others, each seen by one. That such are the facts can be tested by interposing some small opaque object so as to cut off the vision of either of the spots in the figure from the other eye. A vertical partition in the median plane, going from the paper to the nose, will effectually confine each eye's vision to the spot in front of it, and then the single combined spot will be all that appears.[11]

If, instead of two identical spots, we use two different figures, or two differently colored spots, as objects for the two foveæ to look at, they still are seen in the same place; but since they cannot appear as a single object, they appear there alternately displacing each other from the view. This is the phenomenon called retinal rivalry.

As regards the parts of the retinæ round about the foveæ, a similar correspondence obtains. Any impression on the{35} upper half of either retina makes us see an object as below, on the lower half as above, the horizon; and on the right half of either retina, an impression makes us see an object to the left, on the left half one to the right, of the median line. Thus each quadrant of one retina corresponds as a whole to the geometrically similar quadrant of the other; and within two similar quadrants, al and ar for example, there should, if the correspondence were carried out in detail, be geometrically similar points which, if impressed at the same time by light emitted from the same object, should cause that object to appear in the same direction to either eye. Experiment verifies this surmise. If we look at the starry vault with parallel eyes, the stars all seem single; and the laws of perspective show that under the circumstances the parallel light-rays coming from each star must impinge on points within either retina which are geometrically similar to each other. Similarly, a pair of spectacles held an inch or so from the eyes seem like one large median glass. Or we may make an experiment like that with the spots. If we take two exactly similar pictures, no larger than those on an ordinary stereoscopic slide, and if we look at one with each eye (a median partition confining the view) we shall see but one flat picture, all of whose parts appear single. 'Identical retinal points' being impressed, both eyes see their object in the same direction, and the two objects consequently coalesce into one.

Here again retinal rivalry occurs if the pictures differ. And it must be noted that when the experiment is performed{36} for the first time the combined picture is always far from sharp. This is due to the difficulty mentioned on p. 33, of accommodating for anything as near as the surface of the paper, whilst at the same time the convergence is relaxed so that each eye sees the picture in front of itself.

Double Images.—Now it is an immediate consequence of the law of identical location of images falling on geometrically similar points that images which fall upon geometrically DISPARATE points of the two retinæ should be seen in DISPARATE directions, and that their objects should consequently appear in TWO places, or LOOK DOUBLE. Take the parallel rays from a star falling upon two eyes which converge upon a near object, O, instead of being parallel as in the previously instanced case. The two foveæ will receive the images of O, which therefore will look single. If then SL and SR in Fig. 10 be the parallel rays, each of them will fall upon the nasal half of the retina{37} which it strikes. But the two nasal halves are disparate, geometrically symmetrical, not geometrically similar. The star's image on the left eye will therefore appear as if lying to the left of O; its image on the right eye will appear to the right of this point. The star will, in short, be seen double—'homonymously' double.

Conversely, if the star be looked at directly with parallel axes, any near object like O will be seen double, because its images will affect the outer or cheek halves of the two retinæ, instead of one outer and one nasal half. The position of the images will here be reversed from that of the previous case. The right eye's image will now appear to the left, the left eye's to the right; the double images will be 'heteronymous.'

The same reasoning and the same result ought to apply where the object's place with respect to the direction of the two optic axes is such as to make its images fall not on non-similar retinal halves, but on non-similar parts of similar halves. Here, of course, the positions seen will be less widely disparate than in the other case, and the double images will appear to lie less widely apart.

Careful experiments made by many observers according to the so-called haploscopic method confirm this law, and show that corresponding points, of single visual direction, exist upon the two retinæ. For the detail of these one must consult the special treatises.

Vision of Solidity.—This description of binocular vision follows what is called the theory of identical points. On the whole it formulates the facts correctly. The only odd thing is that we should be so little troubled by the innumerable double images which objects nearer and farther than the point looked at must be constantly producing. The answer to this is that we have trained ourselves to habits of inattention in regard to double images. So far as things interest us we turn our foveæ upon them, and they are necessarily seen single; so that if an object impresses disparate points, that may be taken as proof that it is so{38} unimportant for us that we needn't notice whether it appears in one place or in two. By long practice one may acquire great expertness in detecting double images, though, as some one says, it is an art which is not to be learned completely either in one year or in two.

Where the disparity of the images is but slight it is almost impossible to see them as if double. They give rather the perception of a solid object being there. To fix our ideas, take Fig. 11. Suppose we look at the dots in the middle of the lines a and b just as we looked at the spots in Fig. 8. We shall get the same result—i.e., they will coalesce in the median line. But the entire lines will not coalesce, for, owing to their inclination, their tops fall on the temporal, and their bottoms on the nasal, retinal halves. What we see will be two lines crossed in the middle, thus (Fig. 12):

The moment we attend to the tops of these lines, however, our foveæ tend to abandon the dots and to move upwards, and in doing so, to converge somewhat, following the lines, which then appear coalescing at the top as in Fig. 13.

If we think of the bottom, the eyes descend and diverge, and what we see is Fig. 14.

Running our eyes up and down the lines makes them converge and diverge just as they would were they running{39} up and down some single line whose top was nearer to us than its bottom. Now, if the inclination of the lines be moderate, we may not see them double at all, but single throughout their length, when we look at the dots. Under these conditions their top does look nearer than their bottom—in other words, we see them stereoscopically; and we see them so even when our eyes are rigorously motionless. In other words, the slight disparity in the bottom-ends which would draw the foveæ divergently apart makes us see those ends farther, the slight disparity in the top ends which would draw them convergently together makes us see these ends nearer, than the point at which we look. The disparities, in short, affect our perception as the actual movements would.[12]

The Perception of Distance.—When we look about us at things, our eyes are incessantly moving, converging, diverging, accommodating, relaxing, and sweeping over the field. The field appears extended in three dimensions, with some of its parts more distant and some more near.

Subjectively considered, distance is an altogether peculiar content of consciousness. Convergence, accommodation, binocular disparity, size, degree of brightness, parallax, etc., all give us special feelings which are signs of the distance feeling, but not it. They simply suggest it to us. The best way to get it strongly is to go upon some hill-top and invert one's head. The horizon then looks very distant, and draws near as the head erects itself again.

The Perception of Size.—"The dimensions of the retinal image determine primarily the sensations on which conclusions as to size are based; and the larger the visual angle the larger the retinal image: since the visual angle depends on the distance of an object, the correct perception of size depends largely upon a correct perception of distance; having formed a judgment, conscious or unconscious, as to that, we conclude as to size from the extent of the retinal region affected. Most people have been surprised now and then to find that what appeared a large bird in the clouds was only a small insect close to the eye; the large apparent size being due to the previous incorrect judgment as to the distance of the object. The presence of an object of tolerably well-known height, as a man, also assists in forming conceptions (by comparison) as to size; artists for this purpose frequently introduce human figures to assist in giving an idea of the size of other objects represented."[14]

Sensations of Color.—The system of colors is a very complex thing. If one take any color, say green, one can pass{41} away from it in more than one direction, through a series of greens more and more yellowish, let us say, towards yellow, or through another series more and more bluish towards blue. The result would be that if we seek to plot out on paper the various distinguishable tints, the arrangement cannot be that of a line, but has to cover a surface. With the tints arranged on a surface we can pass from any one of them to any other by various lines of gradually changing intermediaries. Such an arrangement is represented in Fig. 15. It is a merely classificatory diagram based on degrees of difference simply felt, and has no physical significance. Black is a color, but does not figure on the plane of the diagram. We cannot place it anywhere alongside of the other colors because we need both to represent the straight gradation from untinted white to black, and that from each pure color towards black as well as towards white. The best way is to put black into the third dimension, beneath the paper, e.g., as is shown perspectively in Fig. 16, then all the transitions can be schematically shown. One can pass straight from black to white, or one can pass round by way of olive, green, and pale green; or one can change from dark blue to yellow through green, or by way of sky-blue, white and straw color; etc., etc. In any case the changes are continuous; and the color system thus forms what Wundt calls a tri-dimensional continuum.

Color-mixture.—Physiologically considered, the colors have this peculiarity, that many pairs of them, when they impress the retina together, produce the sensation of white. The colors which do this are called complementaries. Such are spectral red and green-blue, spectral yellow and indigo-blue. Green and purple, again, are complementaries. All{42} the spectral colors added together also make white light, such as we daily experience in the sunshine. Furthermore, both homogeneous ether-waves and heterogeneous ones may make us feel the same color, when they fall on our retina. Thus yellow, which is a simple spectral color, is also felt when green light is added to red; blue is felt when violet and green lights are mixed. Purple, which is not a spectral color at all, results when the waves either of red and of violet or those of blue and of orange are superposed.[15]

From all this it follows that there is no particular congruence between our system of color-sensations and the physical stimuli which excite them. Each color-feeling is a 'specific energy' (p. 11) which many different physical causes may arouse. Helmholtz, Hering, and others have sought to simplify the tangle of the facts, by physiological hypotheses which, differing much in detail, agree in principle, since they all postulate a limited number of elementary retinal processes to which, when excited singly,{43} certain 'fundamental' colors severally correspond. When excited in combination, as they may be by the most various physical stimuli, other colors, called 'secondary,' are felt. The secondary color-sensations are often spoken of as if they were compounded of the primary sensations. This is a great mistake. The sensations as such are not compounded—yellow, for example, a secondary on Helmholtz's theory, is as unique a quality of feeling as the primaries red and green, which are said to 'compose' it. What are compounded are merely the elementary retinal processes. These, according to their combination, produce diverse results on the brain, and thence the secondary colors result immediately in consciousness. The 'color-theories' are thus physiological, not psychological, hypotheses, and for more information concerning them the reader must consult the physiological books.

The Duration of Luminous Sensations.—"This is greater than that of the stimulus, a fact taken advantage of in making fireworks: an ascending rocket produces the sensation of a trail of light extending far behind the position of the bright part of the rocket itself at the moment, because the sensation aroused by it in a lower part of its course still persists. So, shooting stars appear to have luminous tails behind them. By rotating rapidly before the eye a disk with alternate white and black sectors we get for each point of the retina alternate stimulation (due to the passage of white sector) and rest (when a black sector is passing). If the rotation be rapid enough the sensation aroused is that of a uniform gray, such as would be produced if the white and black were mixed and spread evenly over the disk. In each revolution the eye gets as{44} much light as if that were the case, and is unable to distinguish that this light is made up of separate portions reaching it at intervals: the stimulation due to each lasts until the next begins, and so all are fused together. If one turns out suddenly the gas in a room containing no other light, the image of the flame persists a short time after the flame itself is extinguished."[16] If we open our eyes instantaneously upon a scene, and then shroud them in complete darkness, it will be as if we saw the scene in ghostly light through the dark screen. We can read off details in it which were unnoticed whilst the eyes were open. This is the primary positive after-image, so-called. According to Helmholtz, one third of a second is the most favorable length of exposure to the light for producing it.

Negative after-images are due to more complex conditions, in which fatigue of the retina is usually supposed to play the chief part.

This is one of the facts referred to on p. 27 which have made Hering reject the psychological explanation of simultaneous contrast.

The Intensity of Luminous Objects.—Black is an optical sensation. We have no black except in the field of view;{46} we do not, for instance, see black out of our stomach or out of the palm of our hand. Pure black is, however, only an 'abstract idea,' for the retina itself (even in complete objective darkness) seems to be always the seat of internal changes which give some luminous sensation. This is what is meant by the 'idio-retinal light,' spoken of a few lines back. It plays its part in the determination of all after-images with closed eyes. Any objective luminous stimulus, to be perceived, must be strong enough to give a sensible increment of sensation over and above the idio-retinal light. As the objective stimulus increases the perception is of an intenser luminosity; but the perception changes, as we saw on p. 18, more slowly than the stimulus. The latest numerical determinations, by König and Brodhun, were applied to six different colors and ran from an intensity arbitrarily called 1 to one which was 100,000 times as great. From intensity 2000 to 20,000 Weber's law held good; below and above this range discriminative sensibility declined. The relative increment discriminated here was the same for all colors of light, and lay (according to the tables) between 1 and 2 per cent of the stimulus. Previous observers have got different results.

A certain amount of luminous intensity must exist in an object for its color to be discriminated at all. "In the dark all cats are gray." But the colors rapidly become distincter as the light increases, first the blues and last the reds and yellows, up to a certain point of intensity, when they grow indistinct again through the fact that each takes a turn towards white. At the highest bearable intensity of the light all colors are lost in the blinding white dazzle. This again is usually spoken of as a 'mixing' of the sensation white with the original color-sensation. It is no mixing of two sensations, but the replacement of one sensation by another, in consequence of a changed neural process.{47}

The Ear.—"The auditory organ in man consists of three portions, known respectively as the external ear, the middle ear or tympanum, and the internal ear or labyrinth; the latter contains the end-organs of the auditory nerve. The external ear consists of the expansion seen on the exterior of the head, called the concha, M, Fig. 17,{48} and a passage leading in from it, the external auditory meatus, G. This passage is closed at its inner end by the tympanic or drum membrane, T. It is lined by skin, through which numerous small glands, secreting the wax of the ear, open.

"The Tympanum (P, Fig. 17) is an irregular cavity in the temporal bone, closed externally by the drum membrane. From its inner side the Eustachian tube (R) proceeds and opens into the pharynx. The inner wall of the tympanum is bony except for two small apertures, the oval and round foramens, o and r, which lead into the labyrinth. During life the round aperture is closed by the lining mucous membrane, and the oval by the stirrup-bones. The tympanic membrane T, stretched across the outer side of the tympanum, forms a shallow funnel with its concavity outwards. It is pressed by the external air on its exterior, and by air entering the tympanic cavity through the Eustachian tube on its inner side. If the tympanum were closed these pressures would not be always equal when barometric pressure varied, and the membrane would be bulged in or out according as the external or internal pressure on it were the greater. On the other hand, were the Eustachian tube always open the sounds of our own voices would be loud and disconcerting, so it is usually closed; but every time we swallow it is opened, and thus the air-pressure in the cavity is kept equal to that in the external auditory meatus. On making a balloon ascent or going rapidly down a deep mine, the sudden and great change of aërial pressure outside frequently causes{49} painful tension of the drum-membrane, which may be greatly alleviated by frequent swallowing.

The Auditory Ossicles.—Three small bones lie in the tympanum forming a chain from the drum-membrane to the oval foramen. The external bone is the malleus or hammer; the middle one, the incus or anvil; and the internal one, the stapes or stirrup. They are represented in Fig. 18.[19]

Accommodation is provided for in the ear as well as in the eye. One muscle an inch long, the tensor tympani, arises in the petrous portion of the temporal bone (running in a canal parallel to the Eustachian tube) and is inserted into the malleus below its head. When it contracts, it makes the membrane of the tympanum more tense. Another smaller muscle, the stapedius, goes to the head of the stirrup-bone. These muscles are by many persons felt distinctly contracting when certain notes are heard, and some can make them contract at will. In spite of this, uncertainty still reigns as to their exact use in hearing, though it is highly probable that they give to the membranes which they influence the degree of tension best suited to take up whatever rates of vibration may fall upon them at the time. In listening, the head and ears in lower animals, and the head alone in man, are turned so as best to receive the sound. This also is a part of the reaction called 'adaptation' of the organ (see the chapter on Attention).

The Internal Ear.—"The labyrinth consists primarily of chambers and tubes hollowed out in the temporal bone and inclosed by it on all sides, except for the oval and round foramens on its exterior, and certain apertures for blood-vessels and the auditory nerve; during life all these are closed water-tight in one way or another. Lying in the bony labyrinth thus constituted are membranous parts, of the same general form but smaller, so that between the two{50} a space is left; this is filled with a watery fluid, called the perilymph; and the membranous internal ear is filled by a similar liquid, the endolymph.

The Bony Labyrinth.—"The bony labyrinth is described in three portions, the vestibule, the semicircular canals, and the cochlea; casts of its interior are represented from different aspects in Fig. 19. The vestibule is the central part and has on its exterior the oval foramen (Fv) into which the base of the stirrup-bone fits. Behind the vestibule are three bony semicircular canals, communicating with the back of the vestibule at each end, and dilated near one end to form an ampulla. The bony cochlea is a tube coiled on itself somewhat like a snail's shell, and lying in front of the vestibule.

The Membranous Labyrinth.—"The membranous vestibule, lying in the bony, consists of two sacs communicating by a narrow aperture. The posterior is called the utriculus, and into it the membranous semicircular canals open. The anterior, called the sacculus, communicates by a tube with the membranous cochlea. The membranous semicircular canals much resemble the bony, and each has{51}

an ampulla; in the ampulla one side of the membranous tube is closely adherent to its bony protector; at this point nerves enter the former. The relations of the membranous to the bony cochlea are more complicated. A section through this part of the auditory apparatus (Fig. 20) shows that its osseous portion consists of a tube wound two and a half times round a central bony axis, the modiolus. From the axis a shelf, the lamina spiralis, projects and partially subdivides the tube, extending farthest across in its lower coils. Attached to the outer edge of this bony plate is the membranous cochlea (scala media), a tube triangular in cross-section and attached by its base to the outer side of the bony cochlear spiral. The spiral lamina and the membranous cochlea thus subdivide the cavity of the bony tube (Fig. 21) into an upper portion, the scala vestibuli, SV, and a lower, the scala tympani, ST. Between these lie the lamina spiralis (lso) and the membranous{52} cochlea (CC), the latter being bounded above by the membrane of Reissner (R) and below by the basilar membrane (b)."[20]

The membranous cochlea does not extend to the tip of the bony cochlea; above its apex the scala vestibuli and scala tympani communicate. Both are filled with perilymph, so that when the stapes is pushed into the oval foramen, o, in Fig. 17, by the impact of an air-wave on the tympanic membrane, a wave of perilymph runs up the scala vestibuli to the top, where it turns into the scala tympani, down whose whorls it runs and pushes out the round foramen r, ruffling probably the membrane of Reissner and the basilar membrane on its way up and down.

The Terminal Organs.—"The membranous cochlea contains certain solid structures seated on the basilar membrane and forming the organ of Corti. This contains the end-organs of the cochlear nerves. Lining the sulcus spiralis, a groove in the edge of the bony lamina spiralis, are cuboidal cells; on the inner margin of the basilar membrane they become columnar, and then are succeeded by a row which bear on their upper ends a set of short stiff hairs, and constitute the inner hair-cells, which are fixed below by a narrow apex to the basilar membrane; nerve-fibres enter them. To the inner hair-cells succeed the{53} rods of Corti (Co, Fig. 21), which are represented highly magnified in Fig. 22. These rods are stiff and arranged side by side in two rows, leaned against one another by their upper ends so as to cover in a tunnel; they are known respectively as the inner and outer rods, the former being nearer the lamina spiralis. The inner rods are more numerous than the outer, the numbers being about 6000 and 4500 respectively. Attached to the external sides of the heads of the outer rods is the reticular membrane (r, Fig. 22), which is stiff and perforated by holes. External to the outer rods come four rows of outer hair-cells, connected like the inner row with nerve-fibres; their bristles project into the holes of the reticular membrane. Beyond the outer hair-cells is ordinary columnar epithelium, which passes gradually into cuboidal cells lining most of the membranous cochlea. From the upper lip of the sulcus spiralis projects the tectorial membrane (t, Fig. 21) which extends over the rods of Corti and the hair-cells."[21]

The hair-cells would thus seem to be the terminal organs for 'picking up' the vibrations which the air-waves communicate through all the intervening apparatus, solid and liquid, to the basilar membrane. Analogous hair-cells receive the terminal nerve-filaments in the walls of the saccule, utricle, and ampullæ (see Fig. 23).

The Various Qualities of Sound.—Physically, sounds consist of vibrations, and these are, generally speaking, aërial waves. When the waves are non-periodic the result is a{54} noise; when periodic it is what is nowadays called a tone, or note. The loudness of a sound depends on the force of the waves. When they recur periodically a peculiar quality called pitch is the effect of their frequency. In addition to loudness and pitch tones have each their voice or timbre, which may differ widely in different instruments giving equally loud tones of the same pitch. This voice depends on the form of the aërial wave.

Pitch.—A single puff of air, set in motion by no matter what cause, will give a sensation of sound, but it takes at least four or five puffs, or more, to convey a sensation of pitch. The pitch of the note c, for instance, is due to 132 vibrations a second, that of its octave c´ is produced by twice as many, or 264 vibrations; but in neither case is it necessary for the vibrations to go on during a full second for the pitch to be discerned. "Sound vibrations may be too rapid or too slow in succession to produce sonorous sensations, just as the ultra-violet and ultra-red rays of the solar spectrum fail to excite the retina. The highest-pitched audible note answers to about 38,016 vibrations in a second, but it differs in individuals; many persons cannot hear the cry of a bat nor the chirp of a cricket, which lie near this upper audible limit. On the other hand, sounds of vibrational rate about 40 per second are not well heard, and a little below this they produce rather a 'hum' than a true tone-sensation, and are only used along with notes of higher octaves to which they give a character of greater depth."[22]

The entire system of pitches forms a continuum of one dimension; that is to say, you can pass from one pitch to another only by one set of intermediaries, instead of by more than one, as in the case of colors. (See p. 41.) The whole series of pitches is embraced in and between the terms of what is called the musical scale. The adoption of certain arbitrary points in this scale as 'notes' has an explanation{55} partly historic and partly æsthetic, but too complex for exposition here.

The 'timbre' of a note is due to its wave-form. Waves are either simple ('pendular') or compound. Thus if a tuning-fork (which gives waves nearly simple) vibrate 132 times a second, we shall hear the note c. If simultaneously a fork of 264 vibrations be struck, giving the next higher octave, c´, the aërial movement at any time will be the algebraic sum of the movements due to both forks; whenever both drive the air one way they reinforce one another; when on the contrary the recoil of one fork coincides with the forward stroke of another, they detract from each other's effect. The result is a movement which is still periodic, repeating itself at equal intervals of time, but no longer pendular, since it is not alike on the ascending and descending limbs of the curves. We thus get at the fact that non-pendular vibrations may be produced by the fusion of pendular, or, in technical phrase, by their composition.

Suppose several musical instruments, as those of an orchestra, to be sounded together. Each produces its own effect on the air-particles, whose movements, being an algebraical sum, must at any given instant be very complex; yet the ear can pick out at will and follow the tones of any one instrument. Now in most musical instruments it is susceptible of physical proof that with every single note that is sounded many upper octaves and other 'harmonics' sound simultaneously in fainter form. On the relative strength of this or that one or more of these Helmholtz has shown that the instrument's peculiar voice depends. The several vowel-sounds in the human voice also depend on the predominance of diverse upper harmonics accompanying the note on which the vowel is sung. When the two tuning-forks of the last paragraph are sounded together the new form of vibration has the same period as the lower-pitched fork; yet the ear can clearly distinguish the resultant sound from that of the lower fork alone, as a note of the same pitch but of different timbre; and within{56} the compound sound the two components can by a trained ear be severally heard. Now how can one resultant wave-form make us hear so many sounds at once?

The analysis of compound wave-forms is supposed (after Helmholtz) to be effected through the different rates of sympathetic resonance of the different parts of the membranous cochlea. The basilar membrane is some twelve times broader at the apex of the cochlea than at the base where it begins, and is largely composed of radiating fibres which may be likened to stretched strings. Now the physical principle of sympathetic resonance says that when stretched strings are near a source of vibration those whose own rate agrees with that of the source also vibrate, the others remaining at rest. On this principle, waves of perilymph running down the scala tympani at a certain rate of frequency ought to set certain particular fibres of the basilar membrane vibrating, and ought to leave others unaffected. If then each vibrating fibre stimulated the hair-cell above it, and no others, and each such hair-cell, sending a current to the auditory brain-centre, awakened therein a specific process to which the sensation of one particular pitch was correlated, the physiological condition of our several pitch-sensations would be explained. Suppose now a chord to be struck in which perhaps twenty different physical rates of vibration are found: at least twenty different hair-cells or end-organs will receive the jar; and if the power of mental discrimination be at its maximum, twenty different 'objects' of hearing, in the shape of as many distinct pitches of sound, may appear before the mind.

The rods of Corti are supposed to be dampers of the fibres of the basilar membrane, just as the malleus, incus, and stapes are dampers of the tympanic membrane, as well as transmitters of its oscillations to the inner ear. There must be, in fact, an instantaneous damping of the physiological vibrations, for there are no such positive after-images, and no such blendings of rapidly successive tones, as the retina shows us in the case of light. Helmholtz's theory of{57} the analysis of sounds is plausible and ingenious. One objection to it is that the keyboard of the cochlea does not seem extensive enough for the number of distinct resonances required. We can discriminate many more degrees of pitch than the 20,000 hair-cells, more or less, will allow for.

The so-called Fusion of Sensations in Hearing.—A very common way of explaining the fact that waves which singly give no feeling of pitch give one when recurrent, is to say that their several sensations fuse into a compound sensation. A preferable explanation is that which follows the analogy of muscular contraction. If electric shocks are sent into a frog's sciatic nerve at slow intervals, the muscle which the nerve supplies will give a series of distinct twitches, one for each shock. But if they follow each other at the rate of as many as thirty a second, no distinct twitches are observed, but a steady state of contraction instead. This steady contraction is known as tetanus. The experiment proves that there is a physiological cumulation or overlapping of processes in the muscular tissue. It takes a twentieth of a second or more for the latter to relax after the twitch due to the first shock. But the second shock comes in before the relaxation can occur, then the third again, and so on; so that continuous tetanus takes the place of discrete twitching. Similarly in the auditory nerve. One shock of air starts in it a current to the auditory brain-centre, and affects the latter, so that a dry stroke of sound is heard. If other shocks follow slowly, the brain-centre recovers its equilibrium after each, to be again upset in the same way by the next, and the result is that for each shock of air a distinct sensation of sound occurs. But if the shock comes in too quick succession, the later ones reach the brain before the effects of the earlier ones on that organ have died away. There is thus an overlapping of processes in the auditory centre, a physiological condition analogous to the muscle's tetanus, to which new condition a new quality of feeling, that of pitch, directly corresponds. This latter{58} feeling is a new kind of sensation altogether, not a mere 'appearance' due to many sensations of dry stroke being compounded into one. No sensations of dry stroke can exist under these circumstances, for their physiological conditions have been replaced by others. What 'compounding' there is has already taken place in the brain-cells before the threshold of sensation was reached. Just so red light and green light beating on the retina in rapid enough alternation, arouse the central process to which the sensation yellow directly corresponds. The sensations of red and of green get no chance, under such conditions, to be born. Just so if the muscle could feel, it would have a certain sort of feeling when it gave a single twitch, but it would undoubtedly have a distinct sort of feeling altogether, when it contracted tetanically; and this feeling of the tetanic contraction would by no means be identical with a multitude of the feelings of twitching.

Harmony and Discord.—When several tones sound together we may get peculiar feelings of pleasure or displeasure designated as consonance and dissonance respectively. A note sounds most consonant with its octave. When with the octave the 'third' and the 'fifth' of the note are sounded, for instance c—e—g—c´, we get the 'full chord' or maximum of consonance. The ratios of vibration here are as 4:5:6:8, so that one might think simple ratios were the ground of harmony. But the interval c—d is discordant, with the comparatively simple ratio 8:9. Helmholtz explains discord by the overtones making 'beats' together. This gives a subtle grating which is unpleasant. Where the overtones make no 'beats', or beats too rapid for their effect to be perceptible, there is consonance, according to Helmholtz, which is thus a negative rather than a positive thing. Wundt explains consonance by the presence of strong identical overtones in the notes which harmonize. No one of these explanations of musical harmony can be called quite satisfactory; and the subject is too intricate to be treated farther in this place.{59}

Discriminative Sensibility of the Ear.—Weber's law holds fairly well for the intensity of sounds. If ivory or metal balls are dropped on an ebony or iron plate, they make a sound which is the louder as they are heavier or dropped from a greater height. Experimenting in this way (after others) Merkel found that the just perceptible increment of loudness required an increase of ³/₁₀ of the original stimulus everywhere between the intensities marked 20 and 5000 of his arbitrary scale. Below this the fractional increment of stimulus must be larger; above it, no measurements were made.

Discrimination of differences of pitch varies in different parts of the scale. In the neighborhood of 1000 vibrations per second, one fifth of a vibration more or less can make the sound sharp or flat for a good ear. It takes a much greater relative alteration to sound sharp or flat elsewhere on the scale. The chromatic scale itself has been used as an illustration of Weber's law. The notes seem to differ equally from each other, yet their vibration-numbers form a series of which each is a certain multiple of the last. This, however, has nothing to do with intensities or just perceptible differences; so the peculiar parallelism between the sensation series and the outer-stimulus series forms here a case all by itself, rather than an instance under Weber's more general law.{60}

Nerve-endings in the Skin.—"Many of the afferent skin-nerves end in connection with hair-bulbs; the fine hairs over most of the cutaneous surface, projecting from the skin, transmit any movement impressed on them, with increased force, to the nerve-fibres at their fixed ends. Fine branches of axis-cylinders have also been described as penetrating between epidermic cells and ending there without terminal organs. In or immediately beneath the skin several peculiar forms of nerve end-organs have also been described; they are known as (1) Touch-cells; (2) Pacinian corpuscles; (3) Tactile corpuscles; (4) End-bulbs."[23]

These bodies all consist essentially of granules formed of connective tissue, in which or round about which one or more sensory nerve-fibres terminate. They probably magnify impressions just as a grain of sand does in a shoe, or a crumb does in a finger of a glove.

Touch, or the Pressure Sense.—"Through the skin we get several kinds of sensation; touch proper, heat and cold, and pain; and we can with more or less accuracy localize them on the surface of the body. The interior of the mouth possesses also three sensibilities. Through touch proper we recognize pressure or traction exerted on the skin, and the force of the pressure; the softness or hardness, roughness or smoothness, of the body producing it;{61} and the form of this when not too large to be felt all over. When to learn the form of an object we move the hand over it, muscular sensations are combined with proper tactile, and such a combination of the two sensations is frequent; moreover, we rarely touch anything without at the same time getting temperature sensations; therefore pure tactile feelings are rare. From an evolution point of view, touch is probably the first distinctly differentiated sensation, and this primary position it still largely holds in our mental life."[24]

Objects are most important to us when in direct contact. The chief function of our eyes and ears is to enable us to prepare ourselves for contact with approaching bodies, or to ward such contact off. They have accordingly been characterized as organs of anticipatory touch.

"The delicacy of the tactile sense varies on different parts of the skin; it is greatest on the forehead, temples, and back of the forearm, where a weight of 2 milligr. pressing on an area of 9 sq. millim. can be felt.

"In order that the sense of touch may be excited neighboring skin-areas must be differently pressed. When the hand is immersed in a liquid, as mercury, which fits into all its inequalities and presses with practically the same weight on all neighboring immersed areas, the sense of pressure is only felt at a line along the surface, where the immersed and non-immersed parts of the skin meet.

The Localizing Power of the Skin.—"When the eyes are closed and a point of the skin is touched we can with some accuracy indicate the region stimulated; although tactile feelings are in general characters alike, they differ in something besides intensity by which we can distinguish them; some sub-sensation quality not rising definitely into prominence in consciousness must be present, comparable to the upper partials determining the timbre of a tone. The accuracy of the localizing power varies widely in different{62} skin regions and is measured by observing the least distance which must separate two objects (as the blunted points of a pair of compasses) in order that they may be felt as two. The following table illustrates some of the differences observed:

The localizing power is a little more acute across the long axis of a limb than in it; and is better when the pressure is only strong enough to just cause a distinct tactile sensation than when it is more powerful; it is also very readily and rapidly improvable by practice." It seems to be naturally delicate in proportion as the skin which possesses it covers a more movable part of the body.

"It might be thought that this localizing power depended directly on nerve-distribution; that each touch-nerve had connection with a special brain-centre at one end (the excitation of which caused a sensation with a characteristic local sign), and at the other end was distributed over a certain skin-area, and that the larger this area the farther apart might two points be and still give rise to only one sensation. If this were so, however, the peripheral tactile areas (each being determined by the{63} anatomical distribution of a nerve-fibre) must have definite unchangeable limits, which experiment shows that they do not possess. Suppose the small areas in Fig. 25 to each represent a peripheral area of nerve-distribution. If any two points in c were touched we should according to the theory get but a single sensation; but if, while the compass-points remained the same distance apart, or were even approximated, one were placed in c and the other on a contiguous area, two fibres would be stimulated and we ought to get two sensations; but such is not the case; on the same skin-region the points must be always the same distance apart, no matter how they be shifted, in order to give rise to two just distinguishable sensations.

"It is probable that the nerve-areas are much smaller than the tactile; and that several unstimulated must intervene between the excited, in order to produce sensations which shall be distinct. If we suppose twelve unexcited nerve-areas must intervene, then, in Fig. 25, a and b will be just on the limits of a single tactile area; and no matter how the points are moved, so long as eleven, or fewer, unexcited areas come between, we would get a single tactile sensation; in this way we can explain the fact that tactile areas have no fixed boundaries in the skin, although the nerve-distribution in any part must be constant. We also see why the back of a knife laid on the surface causes a continuous linear sensation, although it touches many distinct nerve-areas. If we could discriminate the excitations of each of these from that of its immediate neighbors we should get the sensation of a series of points touching us, one for each nerve-region excited; but in the absence of intervening unexcited nerve-areas the sensations are fused together.

The Temperature-sense. Its Terminal Organs.—"By this we mean our faculty of perceiving cold and warmth; and, with the help of these sensations, of perceiving temperature differences in external objects. Its organ is the whole skin, the mucous membrane of mouth and fauces, pharynx{64} and gullet, and the entry of the nares. Direct heating or cooling of a sensory nerve may stimulate it and cause pain, but not a true temperature-sensation; hence we assume the presence of temperature end-organs. [These have not yet been ascertained anatomically. Physiologically, however, the demonstration of special spots in the skin for feeling heat and cold is one of the most interesting discoveries of recent years. If one draw a pencil-point over the palm or cheek one will notice certain spots of sudden coolness. These are the cold-spots; the heat-spots are less easy to single out. Goldscheider, Blix, and Donaldson have made minute exploration of determinate tracts of skin and found the heat-and cold-spots thick-set and permanently distinct. Between them no temperature-sensation is excited by contact with a pointed cold or hot object. Mechanical and faradic irritation also excites in these points their specific feelings respectively.]

The feeling of temperature is relative to the state of the skin. "In a comfortable room we feel at no part of the body either heat or cold, although different parts of its surface are at different temperatures; the fingers and nose being cooler than the trunk which is covered by clothes, and this, in turn, cooler than the interior of the mouth. The temperature which a given region of the temperature-organ has (as measured by a thermometer) when it feels neither heat nor cold, is its temperature-sensation zero, and is not associated with any one objective temperature; for not only, as we have just seen, does it vary in different parts of the organ, but also on the same part from time to time. Whenever a skin-region has a temperature above its sensation-zero we feel warmth; and vice versa: the sensation is more marked the greater the difference, and the more suddenly it is produced; touching a metallic body, which{65} conducts heat rapidly to or from the skin, causes a more marked hot or cold sensation than touching a worse conductor, as a piece of wood, of the same temperature.

"The change of temperature in the organ may be brought about by changes in the circulatory apparatus (more blood flowing through the skin warms it and less leads to its cooling), or by temperature-changes in gases, liquids, or solids in contact with it. Sometimes we fail to distinguish clearly whether the cause is external or internal; a person coming in from a windy walk often feels a room uncomfortably warm which is not really so; the exercise has accelerated his circulation and tended to warm his skin, but the moving outer air has rapidly conducted off the extra heat; on entering the house the stationary air there does this less quickly, the skin gets hot, and the cause is supposed to be oppressive heat of the room. Hence, frequently, opening windows and sitting in a draught, with its concomitant risks; whereas keeping quiet for five or ten minutes, until the circulation has returned to its normal rate, would attain the same end without danger.

"The acuteness of the temperature-sense is greatest at temperatures within a few degrees of 30° C. (86° F.); at these differences of less than 0.1° C. can be discriminated. As a means of measuring absolute temperatures, however, the skin is very unreliable, on account of the changeability of its sensation-zero. We can localize temperature-sensations much as tactile, but not so accurately."[25]

Muscular Sensation.—The sensation in the muscle itself cannot well be distinguished from that in the tendon or in its insertion. In muscular fatigue the insertions are the places most painfully felt. In muscular rheumatism, however, the whole muscle grows painful; and violent contraction such as that caused by the faradic current, or known as cramp, produces a severe and peculiar pain felt in{66} the whole mass of muscle affected. Sachs also thought that he had demonstrated, both experimentally and anatomically, the existence of special sensory nerve-fibres, distinct from the motor fibres, in the frog's muscle. The latter end in the 'terminal plates,' the former in a network.

Great importance has been attached to the muscular sense as a factor in our perceptions, not only of weight and pressure, but of the space-relations between things generally. Our eyes and our hands, in their explorations of space, move over it and through it. It is usually supposed that without this sense of an intervening motion performed we should not perceive two seen points or two touched points to be separated by an extended interval. I am far from denying the immense participation of experiences of motion in the construction of our space-perceptions. But it is still an open question how our muscles help us in these experiences, whether by their own sensations, or by awakening sensations of motion on our skin, retina, and articular surfaces. The latter seems to me the more probable view, and the reader may be of the same opinion after reading Chapter VI.

Sensibility to Weight.—When we wish to estimate accurately the weight of an object we always, when possible, lift it, and so combine muscular and articular with tactile sensations. By this means we can form much better judgments.

Weber found that whereas ⅓ must be added to a weight resting on the hand for the increase to be felt, the same hand actively 'hefting' the weight could feel an addition of as little as ¹/₁₇. Merkel's recent and very careful experiments, in which the finger pressed down the beam of a balance counterweighted by from 25 to 8020 grams, showed that between 200 and 2000 grams a constant fractional increase of about ¹/₁₃ was felt when there was no movement of the finger, and of about ¹/₁₉ when there was movement. Above and below these limits the discriminative power grew less.{67}

Pain.—The physiology of pain is still an enigma. One might suppose separate afferent fibres with their own end-organs to carry painful impressions to a specific pain-centre. Or one might suppose such a specific centre to be reached by currents of overflow from the other sensory centres when the violence of their inner excitement should have reached a certain pitch. Or again one might suppose a certain extreme degree of inner excitement to produce the feeling of pain in all the centres. It is certain that sensations of every order, which in moderate degrees are rather pleasant than otherwise, become painful when their intensity grows strong. The rate at which the agreeableness and disagreeableness vary with the intensity of a sensation is roughly represented by the dotted curve in Fig. 27. The horizontal line represents the threshold both of sensational and of agreeable sensibility. Below the line is the disagreeble. The continuous curve is that of Weber's law which we learned to know in Fig. 2, p. 18. With the minimal sensation the agreeableness is nil, as the dotted curve shows. It rises at first more slowly than the sensational intensity, then faster; and reaches its maximum before the sensation is near its acme. After its maximum of agreeableness the{68} dotted line rapidly sinks, and soon tumbles below the horizontal into the realm of the disagreeable or painful in which it declines. That all sensations are painful when too strong is a piece of familiar knowledge. Light, sound, odors, the taste of sweet even, cold, heat, and all the skin-sensations, must be moderate to be enjoyed.

The quality of the sensation complicates the question, however, for in some sensations, as bitter, sour, salt, and certain smells, the turning point of the dotted curve must be drawn very near indeed to the beginning of the scale. In the skin the painful quality soon becomes so intense as entirely to overpower the specific quality of the sort of stimulus. Heat, cold, and pressure are indistinguishable when extreme—we only feel the pain. The hypothesis of separate end-organs in the skin receives some corroboration from recent experiments, for both Blix and Goldscheider have found, along with their special heat-and cold spots, also special 'pain-spots' on the skin. Mixed in with these are spots which are quite feelingless. However it may stand with the terminal pain-spots, separate paths of conduction to the brain, for painful and for merely tactile stimulations of the skin, are made probable by certain facts. In the condition termed analgesia, a touch is felt, but the most violent pinch, burn, or electric spark destructive of the tissue will awaken no sensation. This may occur in disease of the cord, by suggestion in hypnotism, or in certain stages of ether and chloroform intoxication. "In rabbits a similar state of things was produced by Schiff, by dividing the gray matter of the cord, leaving the posterior white columns intact. If, on the contrary, the latter were divided and the gray substance left, there was increased sensitiveness to pain, and possibly touch proper was lost. Such experiments make it pretty certain that when afferent impulses reach the spinal cord at any level and there enter its gray matter with the posterior root-fibres, they travel on in different tracts to conscious centres; the tactile ones coming soon out of the gray network and coursing on in a{69} readily conducting white fibre, while the painful ones travel on farther in the gray substance. It is still uncertain if both impulses reach the cord in the same fibres. The gray network conducts nerve-impulses, but not easily; they tend soon to be blocked in it. A feeble (tactile) impulse reaching it by an afferent fibre might only spread a short way and then pass out into a single good conducting fibre in a white column, and proceed to the brain; while a stronger (painful) impulse would radiate farther in the gray matter, and perhaps break out of it by many fibres leading to the brain through the white columns, and so give rise to an incoördinate and ill-localized sensation. That pains are badly localized, and worse the more intense they are, is a well-known fact, which would thus receive an explanation."[26]

Pain also gives rise to ill-coördinated movements of defence. The stronger the pain the more violent the start. Doubtless in low animals pain is almost the only stimulus; and we have preserved the peculiarity in so far that to-day it is the stimulus of our most energetic, though not of our most discriminating, reactions.

Taste, smell, as well as hunger, thirst, nausea, and other so-called 'common' sensations need not be touched on in this book, as almost nothing of psychological interest is known concerning them.{70}

I treat of these in a separate chapter in order to give them the emphasis which their importance deserves. They are of two orders:

1) Sensations of objects moving over our sensory surfaces; and

2) Sensations of our whole person's translation through space.

1) The Sensation of Motion over Surfaces.—This has generally been assumed by physiologists to be impossible until the positions of terminus a quo and terminus ad quem are severally cognized, and the successive occupancies of these positions by the moving body are perceived to be separated by a distinct interval of time. As a matter of fact, however, we cognize only the very slowest motions in this way. Seeing the hand of a clock at XII and afterwards at VI, I judge that it has moved through the interval. Seeing the sun now in the east and again in the west, I infer it to have passed over my head. But we can only infer that which we already generically know in some more direct fashion, and it is experimentally certain that we have the feeling of motion given us as a direct and simple sensation. Czermak long ago pointed out the difference between seeing the motion of the second-hand of a watch, when we look directly at it, and noticing the fact that it has altered its position, whilst our gaze is fixed upon some other point of the dial-plate. In the first case we have a specific quality of sensation which is absent in the second. If the reader will find a portion of his skin—the arm, for example—where a pair of compass-points an inch{71} apart are felt as one impression, and if he will then trace lines a tenth of an inch long on that spot with a pencil-point, he will be distinctly aware of the point's motion and vaguely aware of the direction of the motion. The perception of the motion here is certainly not derived from a preëxisting knowledge that its starting and ending points are separate positions in space, because positions in space ten times wider apart fail to be discriminated as such when excited by the compass-points. It is the same with the retina. One's fingers when cast upon its peripheral portions cannot be counted—that is to say, the five retinal tracts which they occupy are not distinctly apprehended by the mind as five separate positions in space—and yet the slightest movement of the fingers is most vividly perceived as movement and nothing else. It is thus certain that our sense of movement, being so much more delicate than our sense of position, cannot possibly be derived from it.

Vierordt, at almost the same time, called attention to certain persistent illusions, amongst which are these: If another person gently trace a line across our wrist or finger, the latter being stationary, it will feel to us as if the member were moving in the opposite direction to the tracing point. If, on the contrary, we move our limb across a fixed point, it will seem as if the point were moving as well. If the reader will touch his forehead with his forefinger kept motionless, and then rotate the head so that the skin of the forehead passes beneath the finger's tip, he will have an irresistible sensation of the latter being itself in motion in the opposite direction to the head. So in abducting the fingers from each other; some may move and the rest be still, but the still ones will feel as if they were actively separating from the rest. These illusions, according to Vierordt, are survivals of a primitive form of perception, when motion was felt as such, but ascribed to the whole 'content' of consciousness, and not yet distinguished as belonging exclusively to one of its parts. When{72} our perception is fully developed we go beyond the mere relative motion of thing and ground, and can ascribe absolute motion to one of these components of our total object, and absolute rest to another. When, in vision for example, the whole field of view seems to move together, we think it is ourselves or our eyes which are moving; and any object in the foreground which may seem to move relatively to the background is judged by us to be really still. But primitively this discrimination is not perfectly made. The sensation of the motion spreads over all that we see and infects it. Any relative motion of object and retina both makes the object seem to move, and makes us feel ourselves in motion. Even now when our whole field of view really does move we get giddy, and feel as if we too were moving; and we still see an apparent motion of the entire field of view whenever we suddenly jerk our head and eyes or shake them quickly to and fro. Pushing our eyeballs gives the same illusion. We know in all these cases what really happens, but the conditions are unusual, so our primitive sensation persists unchecked. So it does when clouds float by the moon. We know the moon is still; but we see it move faster than the clouds. Even when we slowly move our eyes the primitive sensation persists under the victorious conception. If we notice closely the experience, we find that any object towards which we look appears moving to meet our eye.

But the most valuable contribution to the subject is the paper of G. H. Schneider,[27] who takes up the matter zoölogically, and shows by examples from every branch of the animal kingdom that movement is the quality by which animals most easily attract each other's attention. The instinct of 'shamming death' is no shamming of death at all, but rather a paralysis through fear, which saves the insect, crustacean, or other creature from being noticed at all by his enemy. It is paralleled in the human race by{73} the breath-holding stillness of the boy playing 'I spy,' to whom the seeker is near; and its obverse side is shown in our involuntary waving of arms, jumping up and down, and so forth, when we wish to attract someone's attention at a distance. Creatures 'stalking' their prey and creatures hiding from their pursuers alike show how immobility diminishes conspicuity. In the woods, if we are quiet, the squirrels and birds will actually touch us. Flies will light on stuffed birds and stationary frogs. On the other hand, the tremendous shock of feeling the thing we are sitting on begin to move, the exaggerated start it gives us to have an insect unexpectedly pass over our skin, or a cat noiselessly come and snuffle about our hand, the excessive reflex effects of tickling, etc., show how exciting the sensation of motion is per se. A kitten cannot help pursuing a moving ball. Impressions too faint to be cognized at all are immediately felt if they move. A fly sitting is unnoticed,—we feel it the moment it crawls. A shadow may be too faint to be perceived. If we hold a finger between our closed eyelid and the sunshine we do not notice its presence. The moment we move it to and fro, however, we discern it. Such visual perception as this reproduces the conditions of sight among the radiates.

In ourselves, the main function of the peripheral parts of the retina is that of sentinels, which, when beams of light move over them, cry 'Who goes there?' and call the fovea to the spot. Most parts of the skin do but perform the same office for the finger-tips. Of course movement of surface under object is (for purposes of stimulation) equivalent to movement of object over surface. In exploring the shapes and sizes of things by either eye or skin the movements of these organs are incessant and unrestrainable. Every such movement draws the points and lines of the object across the surface, imprints them a hundred times more sharply, and drives them home to the attention. The immense part thus played by movements in our perceptive activity is held by many psychologists to prove that the{74} muscles are themselves the space-perceiving organ. Not surface-sensibility, but 'the muscular sense,' is for these writers the original and only revealer of objective extension. But they have all failed to notice with what peculiar intensity muscular movements call surface-sensibilities into play, and how largely the mere discernment of impressions depends on the mobility of the surfaces upon which they fall.

Our articular surfaces are tactile organs which become intensely painful when inflamed. Besides pressure, the only stimulus they receive is their motion upon each other. To the sensation of this motion more than anything else seems due the perception of the position which our limbs may have assumed. Patients cutaneously and muscularly anæsthetic in one leg can often prove that their articular sensibility remains, by showing (by movements of their well leg) the positions in which the surgeon may place their insensible one. Goldscheider in Berlin caused fingers, arms, and legs to be passively rotated upon their various joints in a mechanical apparatus which registered both the velocity of movement impressed and the amount of angular rotation. The minimal felt amounts of rotation were much less than a single angular degree in all the joints except those of the fingers. Such displacements as these, Goldscheider says, can hardly be detected by the eye. Anæsthesia of the skin produced by induction-currents had no disturbing effect on the perception, nor did the various degrees of pressure of the moving force upon the skin affect it. It became, in fact, all the more distinct in proportion as the concomitant pressure-feelings were eliminated by artificial anæsthesia. When the joints themselves, however, were made artificially anæsthetic, the perception of the movement grew obtuse and the angular rotations had to be much increased before they were perceptible. All these facts prove, according to Herr Goldscheider, that the joint-surfaces and these alone are the seat of the impressions{75} by which the movements of our members are immediately perceived.

2) Sensations of Movement through Space.—These may be divided, into feelings of rotation and feelings of translation. As was stated at the end of the chapter on the ear, the labyrinth (semicircular canals, utricle and saccule) seems to have nothing to do with hearing. It is conclusively established to-day that the semicircular canals are the organs of a sixth special sense, that namely of rotation. When subjectively excited, this sensation is known as dizziness or vertigo, and rapidly engenders the farther feeling of nausea. Irritative disease of the inner ear causes intense vertigo (Ménière's disease). Traumatic irritation of the canals in birds and mammals makes the animals tumble and throw themselves about in a way best explained by supposing them to suffer from false sensations of falling, etc., which they compensate by reflex muscular acts that throw them the other way. Galvanic irritation of the membranous canals in pigeons cause just the same compensatory movements of head and eye which actual rotations impressed on the creatures produce. Deaf and dumb persons (amongst whom many must have had their auditory nerves or labyrinths destroyed by the same disease which took away their hearing) are in a very large percentage of cases found quite insusceptible of being made dizzy by rotation. Purkinje and Mach have shown that, whatever the organ of the sense of rotation may be, it must have its seat in the head. The body is excluded by Mach's elaborate experiments.

The semicircular canals, being, as it were, six little spirit-levels in three rectangular planes, seem admirably adapted to be organs of a sense of rotation. We need only suppose that when the head turns in the plane of any one of them, the relative inertia of the endolymph momentarily increases its pressure on the nerve-termini in the appropriate ampulla, which pressure starts a current towards the central organ for feeling vertigo. This organ seems to be{76} the cerebellum, and the teleology of the whole business would appear to be the maintenance of the upright position. If a man stand with shut eyes and attend to his body, he will find that he is hardly for a moment in equilibrium. Incipient fallings towards every side in succession are incessantly repaired by muscular contractions which restore the balance; and although impressions on the tendons, ligaments, foot-soles, joints, etc., doubtless are among the causes of the compensatory contractions, yet the strongest and most special reflex arc would seem to be that which has the sensation of incipient vertigo for its afferent member. This is experimentally proved to be much more easily excited than the other sensations referred to. When the cerebellum is disorganized the reflex response fails to occur properly and loss of equilibrium is the result. Irritation of the cerebellum produces vertigo, loss of balance, and nausea; and galvanic currents through the head produce various forms of vertigo correlated with their direction. It seems probable that direct excitement of the cerebellar centre is responsible for these feelings. In addition to these corporeal reflexes the sense of rotation causes compensatory rollings of the eyeballs in the opposite direction, to which some of the subjective phenomena of optical vertigo are due. Steady rotation gives no sensation; it is only starting or stopping, or, more generally speaking, acceleration (positive or negative), which impresses the end-organs in the ampullæ. The sensation always has a little duration, however; and the feeling of reversed movement after whirling violently may last for nearly a minute, slowly fading out.

The cause of the sense of translation (movement forwards or backwards) is more open to dispute. The seat of this sensation has been assigned to the semicircular canals when compounding their currents to the brain; and also to the utricle. The latest experimenter, M. Delage, considers that it cannot possibly be in the head, and assigns it rather to the entire body, so far as its parts (blood-vessels,{77} viscera, etc.) are movable against each other and suffer friction or pressure from their relative inertia when a movement of translation begins. M. Delage's exclusion of the labyrinth from this form of sensibility cannot, however, yet be considered definitively established, so the matter may rest with this mention.{78}

Embryological Sketch.—The brain is a sort of pons asinorum in anatomy until one gets a certain general conception of it as a clue. Then it becomes a comparatively simple affair. The clue is given by comparative anatomy and especially by embryology. At a certain moment in the development of all the higher vertebrates the cerebro-spinal axis is formed by a hollow tube containing fluid and terminated in front by an enlargement separated by transverse constrictions into three 'cerebral vesicles,' so called (see Fig. 28). The walls of these vesicles thicken in most{79} places, change in others into a thin vascular tissue, and in others again send out processes which produce an appearance of farther subdivision. The middle vesicle or mid-brain (Mb in the figures) is the least affected by change. Its upper walls thicken into the optic lobes, or corpora quadrigemina as they are named in man; its lower walls become the so-called peduncles or crura of the brain; and its cavity dwindles into the aqueduct of Silvius. A section through the adult human mid-brain is shown in Fig. 31.

The anterior and posterior vesicles undergo much more considerable change. The walls of the posterior vesicle thicken enormously in their foremost portion and form the cerebellum on top (Cb in all the figures) and the pons Varolii below (P.V. in Fig. 33). In its hindmost portions the posterior vesicle thickens below into the medulla oblongata (Mo in all the figures), whilst on top its walls thin out and melt, so that one can pass a probe into the cavity without breaking through any truly nervous tissue. The cavity which one thus enters from without is named the fourth ventricle (4 in Figs. 32 and 33). One can run the probe forward{80} through it, passing first under the cerebellum and then under a thin sheet of nervous tissue (the valve of Vieussens) just anterior thereto, as far as the aqueduct of Silvius. Passing through this, the probe emerges forward into what was once the cavity of the anterior vesicle. But the covering has melted away at this place, and the cavity now forms a deep compressed pit or groove between the two walls of the vesicle, and is called the third ventricle (3 in Figs. 32 and 33). The 'aqueduct of Sylvius' is in consequence of this connection often called the iter a tertio ad quartum ventriculum. The walls of the vesicle form the optic thalami (Th in all the figures).

From the anterior vesicle just in front of the thalami there buds out on either side an enlargement, into which the cavity of the vesicle continues, and which becomes the hemisphere of that side. In man its walls thicken enormously and form folds, the so-called convolutions, on their surface. At the same time they grow backwards rather than forwards of their starting-point just in front of the thalamus, arching over the latter; and growing fastest along their top circumference, they end by bending downwards and forwards again when they have passed the rear end of the thalamus. When fully developed in man, they overlay and cover in all the other parts of the brain. Their cavities form the lateral ventricles, easier to understand by a dissection than by a description. A probe can be passed into either of them from the third ventricle at its anterior{81} end; and like the third ventricle, their wall is melted down along a certain line, forming a long cleft through which they can be entered without rupturing the nervous tissue. This cleft, on account of the growth of the hemisphere outwards, backwards, and then downwards from its starting point, has got rolled in and tucked away beneath the apparent surface.[29]

At first the two hemispheres are connected only with their respective thalami. But during the fourth and fifth months of embryonic life they become connected with each other above the thalami through the growth between them of a massive system of transverse fibres which crosses the median line like a great bridge and is called the corpus callosum. These fibres radiate in the walls of both hemispheres and form a direct connection between the convolutions of the right and of the left side. Beneath the corpus callosum another system of fibres called the fornix is formed, between which and the corpus callosum there is a peculiar connection. Just in front of the thalami, where the hemispheres begin their growth, a ganglionic mass called the corpus striatum (C.S., Figs. 32 and 33) is formed in their wall. It is complex in structure, consisting of two main parts, called nucleus lenticularis and nucleus candatus respectively. The figures, with their respective explanations, will give a better idea of the farther details of structure than any verbal description; so, after some practical directions for dissecting the organ, I will pass to a brief account of the physiological relations of its different parts to each other.

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When all is said and done, the fact remains that, for the beginner, the understanding of the brain's structure is not an easy thing. It must be gone over and forgotten and learned again many times before it is definitively assimilated by the mind. But patience and repetition, here as elsewhere, will bear their perfect fruit.{91}

General Idea of Nervous Function.—If I begin chopping the foot of a tree, its branches are unmoved by my act, and its leaves murmur as peacefully as ever in the wind. If, on the contrary, I do violence to the foot of a fellow-man, the rest of his body instantly responds to the aggression by movements of alarm or defence. The reason of this difference is that the man has a nervous system, whilst the tree has none; and the function of the nervous system is to bring each part into harmonious coöperation with every other. The afferent nerves, when excited by some physical irritant, be this as gross in its mode of operation as a chopping axe or as subtle as the waves of light, conveys the excitement to the nervous centres. The commotion set up in the centres does not stop there, but discharges through the efferent nerves, exciting movements which vary with the animal and with the irritant applied. These acts of response have usually the common character of being of service. They ward off the noxious stimulus and support the beneficial one; whilst if, in itself indifferent, the stimulus be a sign of some distant circumstance of practical importance, the animal's acts are addressed to this circumstance so as to avoid its perils or secure its benefits, as the case may be. To take a common example, if I hear the conductor calling 'All aboard!' as I enter the station, my heart first stops, then palpitates, and my legs respond to the air-waves falling on my tympanum by quickening their movements. If I stumble as I run, the sensation of falling provokes a movement of the hands towards the direction of the fall, the effect of which is to shield the{92} body from too sudden a shock. If a cinder enter my eye, its lids close forcibly and a copious flow of tears tends to wash it out.

These three responses to a sensational stimulus differ, however, in many respects. The closure of the eye and the lachrymation are quite involuntary, and so is the disturbance of the heart. Such involuntary responses we know as 'reflex' acts. The motion of the arms to break the shock of falling may also be called reflex, since it occurs too quickly to be deliberately intended. It is, at any rate, less automatic than the previous acts, for a man might by conscious effort learn to perform it more skilfully, or even to suppress it altogether. Actions of this kind, into which instinct and volition enter upon equal terms, have been called 'semi-reflex.' The act of running towards the train, on the other hand, has no instinctive element about it. It is purely the result of education, and is preceded by a consciousness of the purpose to be attained and a distinct mandate of the will. It is a 'voluntary act.' Thus the animal's reflex and voluntary performances shade into each other gradually, being connected by acts which may often occur automatically, but may also be modified by conscious intelligence.

The Frog's Nerve-centres.—Let us now look a little more closely at what goes on.

The best way to enter the subject will be to take a lower creature, like a frog, and study by the vivisectional method the functions of his different nerve-centres. The frog's nerve-centres are figured in the diagram over the page, which needs no further explanation. I shall first proceed to state what happens when various amounts of the anterior parts are removed, in different frogs, in the way in which an ordinary student removes them—that is, with no extreme precautions as to the purity of the operation.

If, then, we reduce the frog's nervous system to the spinal cord alone, by making a section behind the base of the skull, between the spinal cord and the medulla oblongata,{93} thereby cutting off the brain from all connection with the rest of the body, the frog will still continue to live, but with a very peculiarly modified activity. It ceases to breathe or swallow; it lies flat on its belly, and does not, like a normal frog, sit up on its forepaws, though its hind-legs are kept, as usual, folded against its body and immediately resume this position if drawn out. If thrown on its back it lies there quietly, without turning over like a normal frog. Locomotion and voice seem entirely abolished. If we suspend it by the nose, and irritate different portions of its skin by acid, it performs a set of remarkable 'defensive' movements calculated to wipe away the irritant. Thus, if the breast be touched, both fore-paws will rub it vigorously; if we touch the outer side of the elbow, the hind-foot of the same side will rise directly to the spot and wipe it. The back of the foot will rub the knee if that be attacked, whilst if the foot be cut away, the stump will make ineffectual movements, and then, in many frogs, a pause will come, as if for deliberation, succeeded by a rapid passage of the opposite unmutilated foot to the acidulated spot.

The most striking character of all these movements, after their teleological appropriateness, is their precision. They vary, in sensitive frogs and with a proper amount of irritation, so little as almost to resemble in their machine-like regularity the performances of a jumping-jack, whose legs must twitch whenever you pull the string. The spinal cord of the frog thus contains arrangements of cells and fibres fitted to convert skin-irritations into movements of defence. We may call it the centre for defensive movements in this animal. We may indeed go farther than this, and by cutting the spinal cord in various places find that its{94} separate segments are independent mechanisms, for appropriate activities of the head and of the arms and legs respectively. The segment governing the arms is especially active, in male frogs, in the breeding season; and these members alone, with the breast and back appertaining to them, and everything else cut away, will actively grasp a finger placed between them and remain hanging to it for a considerable time.

Similarly of the medulla oblongata, optic lobes, and other centres between the spinal cord and the hemispheres of the frog. Each of them is proved by experiment to contain a mechanism for the accurate execution, in response to definite stimuli, of certain special acts. Thus with the medulla the animal swallows; with the medulla and cerebellum together he jumps, swims, and turns over from his back; with his optic lobes he croaks when pinched; etc. A frog which has lost his cerebral hemispheres alone is by an unpractised observer indistinguishable from a normal animal.

Not only is he capable, on proper instigation, of all the acts already mentioned, but he guides himself by sight, so that if an obstacle be set up between him and the light, and he be forced to move forward, he either jumps over it or swerves to one side. He manifests the sexual instinct at the proper seasons, and discriminates between male and female individuals of his own species. He is, in short, so similar in every respect to a normal frog that it would take a person very familiar with these animals to suspect anything wrong or wanting about him; but even then such a person would soon remark the almost entire absence of spontaneous motion—that is, motion unprovoked by any present incitation of sense. The continued movements of swimming, performed by the creature in the water, seem to be the fatal result of the contact of that fluid with its skin. They cease when a stick, for example, touches his hands. This is a sensible irritant towards which the feet are automatically drawn by reflex action, and on which the animal remains sitting. He manifests no hunger, and will{95} suffer a fly to crawl over his nose unsnapped at. Fear, too, seems to have deserted him. In a word, he is an extremely complex machine whose actions, so far as they go, tend to self-preservation; but still a machine, in this sense—that it seems to contain no incalculable element. By applying the right sensory stimulus to him we are almost as certain of getting a fixed response as an organist is of hearing a certain tone when he pulls out a certain stop.

But now if to the lower centres we add the cerebral hemispheres, or if, in other words, we make an intact animal the subject of our observations, all this is changed. In addition to the previous responses to present incitements of sense, our frog now goes through long and complex acts of locomotion spontaneously, or as if moved by what in ourselves we should call an idea. His reactions to outward stimuli vary their form, too. Instead of making simple defensive movements with his hind-legs, like a headless frog, if touched; or of giving one or two leaps and then sitting still like a hemisphereless one, he makes persistent and varied efforts of escape, as if, not the mere contact of the physiologist's hand, but the notion of danger suggested by it were now his spur. Led by the feeling of hunger, too, he goes in search of insects, fish, or smaller frogs, and varies his procedure with each species of victim. The physiologist cannot by manipulating him elicit croaking, crawling up a board, swimming or stopping, at will. His conduct has become incalculable—we can no longer foretell it exactly. Effort to escape is his dominant reaction, but he may do anything else, even swell up and become perfectly passive in our hands.

Such are the phenomena commonly observed, and such the impressions which one naturally receives. Certain general conclusions follow irresistibly. First of all the following:

The acts of all the centres involve the use of the same muscles. When a brainless frog's hind-leg wipes the acid,{96} he calls into play all the leg-muscles which a frog with his full medulla oblongata and cerebellum uses when he turns from his back to his belly. Their contractions are, however, combined differently in the two cases, so that the results vary widely. We must consequently conclude that specific arrangements of cells and fibres exist in the cord for wiping, in the medulla for turning over, etc. Similarly they exist in the thalami for jumping over seen obstacles and for balancing the moved body; in the optic lobes for creeping backwards, or what not. But in the hemispheres, since the presence of these organs brings no new elementary form of movement with it, but only determines differently the occasions on which the movements shall occur, making the usual stimuli less fatal and machine-like, we need suppose no such machinery directly coördinative of muscular contractions to exist. We may rather assume, when the mandate for a wiping-movement is sent forth by the hemispheres, that a current goes straight to the wiping-arrangement in the spinal cord, exciting this arrangement as a whole. Similarly, if an intact frog wishes to jump, all he need do is to excite from the hemispheres the jumping-centre in the thalami or wherever it may be, and the latter will provide for the details of the execution. It is like a general ordering a colonel to make a certain movement, but not telling him how it shall be done.

The same muscle, then, is repeatedly represented at different heights; and at each it enters into a different combination with other muscles to coöperate in some special form of concerted movement. At each height the movement is discharged by some particular form of sensorial stimulus, whilst the stimuli which discharge the hemispheres would seem not so much to be elementary sorts of sensation, as groups of sensations forming determinate objects or things.

The Pigeon's Lower Centres.—The results are just the same if, instead of a frog, we take a pigeon, cut out his hemispheres carefully and wait till he recovers from the{97} operation. There is not a movement natural to him which this brainless bird cannot execute; he seems, too, after some days to execute movements from some inner irritation, for he moves spontaneously. But his emotions and instincts exist no longer. In Schrader's striking words:

"The hemisphereless animal moves in a world of bodies which ... are all of equal value for him.... He is, to use Goltz's apt expression, impersonal.... Every object is for him only a space-occupying mass, he turns out of his path for an ordinary pigeon no otherwise than for a stone. He may try to climb over both. All authors agree that they never found any difference, whether it was an inanimate body, a cat, a dog, or a bird of prey which came in their pigeon's way. The creature knows neither friends nor enemies, in the thickest company it lives like a hermit. The languishing cooing of the male awakens no more impression than the rattling of the peas, or the call-whistle which in the days before the injury used to make the birds hasten to be fed. Quite as little as the earlier observers have I seen hemisphereless she-birds answer the courting of the male. A hemisphereless male will coo all day long and show distinct signs of sexual excitement, but his activity is without any object, it is entirely indifferent to him whether the she-bird be there or not. If one is placed near him, he leaves her unnoticed.... As the male pays no attention to the female, so she pays none to her young. The brood may follow the mother ceaselessly calling for food, but they might as well ask it from a stone.... The hemisphereless pigeon is in the highest degree tame, and fears man as little as cat or bird of prey."

General Notion of Hemispheres.—All these facts lead us, when we try to formulate them broadly, to some such conception as this: The lower centres act from present sensational stimuli alone; the hemispheres act from considerations, the sensations which they may receive serving only as suggesters of these. But what are considerations but expectations, in the fancy, of sensations which will be felt one way or another according as action takes this course or{98} that? If I step aside on seeing a rattlesnake, from considering how dangerous an animal he is, the mental materials which constitute my prudential reflection are images more or less vivid of the movement of his head, of a sudden pain in my leg, of a state of terror, a swelling of the limb, a chill, delirium, death, etc., etc., and the ruin of my hopes. But all these images are constructed out of my past experiences. They are reproductions of what I have felt or witnessed. They are, in short, remote sensations; and the main difference between the hemisphereless animal and the whole one may be concisely expressed by saying that the one obeys absent, the other only present, objects.

The hemispheres would then seem to be the chief seat of memory. Vestiges of past experience must in some way be stored up in them, and must, when aroused by present stimuli, first appear as representations of distant goods and evils; and then must discharge into the appropriate motor channels for warding off the evil and securing the benefits of the good. If we liken the nervous currents to electric currents, we can compare the nervous system, C, below the hemispheres to a direct circuit from sense-organ to muscle along the line S ...C ...M of Fig. 40. The hemisphere, H, adds the long circuit or loop-line through which the current may pass when for any reason the direct line is not used.

Thus, a tired wayfarer on a hot day throws himself on the damp earth beneath a maple-tree. The sensations of delicious rest and coolness pouring themselves through the direct line would naturally discharge into the muscles of complete extension: he would abandon himself to the dangerous repose. But the loop-line being open, part of the current is drafted along it, and awakens rheumatic or catarrhal reminiscences, which prevail over the instigations of sense, and make the man arise and pursue his way{99} to where he may enjoy his rest more safely. Presently we shall examine the manner in which the hemispheric loop-line may be supposed to serve as a reservoir for such reminiscences as these. Meanwhile I will ask the reader to notice some corollaries of its being such a reservoir.

First, no animal without it can deliberate, pause, postpone, nicely weigh one motive against another, or compare. Prudence, in a word, is for such a creature an impossible virtue. Accordingly we see that nature removes those functions in the exercise of which prudence is a virtue from the lower centres and hands them over to the cerebrum. Wherever a creature has to deal with complex features of the environment, prudence is a virtue. The higher animals have so to deal; and the more complex the features, the higher we call the animals. The fewer of his acts, then, can such an animal perform without the help of the organs in question. In the frog many acts devolve wholly on the lower centres; in the bird fewer; in the rodent fewer still; in the dog very few indeed; and in apes and men hardly any at all.

The advantages of this are obvious. Take the prehension of food as an example and suppose it to be a reflex performance of the lower centres. The animal will be condemned fatally and irresistibly to snap at it whenever presented, no matter what the circumstances may be; he can no more disobey this prompting than water can refuse to boil when a fire is kindled under the pot. His life will again and again pay the forfeit of his gluttony. Exposure to retaliation, to other enemies, to traps, to poisons, to the dangers of repletion, must be regular parts of his existence. His lack of all thought by which to weigh the danger against the attractiveness of the bait, and of all volition to remain hungry a little while longer, is the direct measure of his lowness in the mental scale. And those fishes which, like our cunners and sculpins, are no sooner thrown back from the hook into the water than they automatically seize the hook again, would soon expiate the degradation of their{100} intelligence by the extinction of their type, did not their extraordinary fecundity atone for their imprudence. Appetite and the acts it prompts have consequently become in all higher vertebrates functions of the cerebrum. They disappear when the physiologist's knife has left the subordinate centres alone in place. The brainless pigeon will starve though left on a corn-heap.

Take again the sexual function. In birds this devolves exclusively upon the hemispheres. When these are shorn away the pigeon pays no attention to the billings and cooings of its mate. It is the same, according to Goltz, with male dogs who have suffered large losses of cerebral tissue. Those who have read Darwin's Descent of Man will recollect what an importance this author ascribes to the agency of sexual selection in the amelioration of the breeds of birds. The females are naturally coy, and their coyness must be overcome by the exhibition of the gorgeous plumage, and various accomplishments in the way of strutting and fighting, of the males. In frogs and toads, on the other hand, where (as we saw on page 94) the sexual instinct devolves upon the lower centres, we find a machine-like obedience to the present incitements of sense, and an almost total exclusion of the power of choice. The consequence is that every spring an immense waste of batrachian life, involving numbers of adult animals and innumerable eggs, takes place from no other cause than the blind character of the sexual impulse in these creatures.

No one need be told how dependent all human social elevation is upon the prevalence of chastity. Hardly any factor measures more than this the difference between civilization and barbarism. Physiologically interpreted, chastity means nothing more than the fact that present solicitations of sense are overpowered by suggestions of æsthetic and moral fitness which the circumstances awaken in the cerebrum; and that upon the inhibitory or permissive influence of these alone action directly depends.

Within the psychic life due to the cerebrum itself the{101} same general distinction obtains, between considerations of the more immediate and considerations of the more remote. In all ages the man whose determinations are swayed by reference to the most distant ends has been held to possess the highest intelligence. The tramp who lives from hour to hour; the bohemian whose engagements are from day to day; the bachelor who builds but for a single life; the father who acts for another generation; the patriot who thinks of a whole community and many generations; and, finally, the philosopher and saint whose cares are for humanity and for eternity,—these range themselves in an unbroken hierarchy, wherein each successive grade results from an increased manifestation of the special form of action by which the cerebral centres are distinguished from all below them.

The Automaton-Theory.—In the 'loop-line' along which the memories and ideas of the distant are supposed to lie, the action, so far as it is a physical process, must be interpreted after the type of the action in the lower centres. If regarded here as a reflex process, it must be reflex there as well. The current in both places runs out into the muscles only after it has first run in; but whilst the path by which it runs out is determined in the lower centres by reflections few and fixed amongst the cell-arrangements, in the hemispheres the reflections are many and instable. This, it will be seen, is only a difference of degree and not of kind, and does not change the reflex type. The conception of all action as conforming to this type is the fundamental conception of modern nerve-physiology. This conception, now, has led to two quite opposite theories about the relation to consciousness of the nervous functions. Some authors, finding that the higher voluntary functions seem to require the guidance of feeling, conclude that over the lowest reflexes some such feeling also presides, though it may be a feeling connected with the spinal cord, of which the higher conscious self connected with the hemispheres remains unconscious. Others, finding that{102} reflex and semi-automatic acts may, notwithstanding their appropriateness, take place with an unconsciousness apparently complete, fly to the opposite extreme and maintain that the appropriateness even of the higher voluntary actions connected with the hemispheres owes nothing to the fact that consciousness attends them. They are, according to these writers, results of physiological mechanism pure and simple.

To comprehend completely this latter doctrine one should apply it to examples. The movements of our tongues and pens, the flashings of our eyes in conversation, are of course events of a physiological order, and as such their causal antecedents may be exclusively mechanical. If we knew thoroughly the nervous system of Shakespeare, and as thoroughly all his environing conditions, we should be able, according to the theory of automatism, to show why at a given period of his life his hand came to trace on certain sheets of paper those crabbed little black marks which we for shortness' sake call the manuscript of Hamlet. We should understand the rationale of every erasure and alteration therein, and we should understand all this without in the slightest degree acknowledging the existence of the thoughts in Shakespeare's mind. The words and sentences would be taken, not as signs of anything beyond themselves, but as little outward facts, pure and simple. In like manner, the automaton-theory affirms, we might exhaustively write the biography of those two hundred pounds, more or less, of warmish albuminoid matter called Martin Luther, without ever implying that it felt.

But, on the other hand, nothing in all this could prevent us from giving an equally complete account of either Luther's or Shakespeare's spiritual history, an account in which every gleam of thought and emotion should find its place. The mind-history would run alongside of the body-history of each man, and each point in the one would correspond to, but not react upon, a point in the other. So the melody floats from the harp-string, but neither checks{103} nor quickens its vibrations; so the shadow runs alongside the pedestrian, but in no way influences his steps.

As a mere conception, and so long as we confine our view to the nervous centres themselves, few things are more seductive than this radically mechanical theory of their action. And yet our consciousness is there, and has in all probability been evolved, like all other functions, for a use—it is to the highest degree improbable a priori that it should have no use. Its use seems to be that of selection; but to select, it must be efficacious. States of consciousness which feel right are held fast to; those which feel wrong are checked. If the 'holding' and the 'checking' of the conscious states severally mean also the efficacious reinforcing or inhibiting of the correlated neural processes, then it would seem as if the presence of the states of mind might help to steer the nervous system and keep it in the path which to the consciousness seemed best. Now on the average what seems best to consciousness is really best for the creature. It is a well-known fact that pleasures are generally associated with beneficial, pains with detrimental, experiences. All the fundamental vital processes illustrate this law. Starvation; suffocation; privation of food, drink, and sleep; work when exhausted; burns, wounds, inflammation; the effects of poison, are as disagreeable as filling the hungry stomach, enjoying rest and sleep after fatigue, exercise after rest, and a sound skin and unbroken bones at all times, are pleasant. Mr. Spencer and others have suggested that these coincidences are due, not to any preëstablished harmony, but to the mere action of natural selection, which would certainly kill off in the long-run any breed of creatures to whom the fundamentally noxious experience seemed enjoyable. An animal that should take pleasure in a feeling of suffocation would, if that pleasure were efficacious enough to make him keep his head under water, enjoy a longevity of four or five minutes. But if conscious pleasure does not reinforce, and conscious pain does not{104} inhibit, anything, one does not see (without some such a priori rational harmony as would be scouted by the 'scientific' champions of the automaton-theory) why the most noxious acts, such as burning, might not with perfect impunity give thrills of delight, and the most necessary ones, such as breathing, cause agony. The only considerable attempt that has been made to explain the distribution of our feelings is that of Mr. Grant Allen in his suggestive little work, Physiological Æsthetics; and his reasoning is based exclusively on that causal efficacy of pleasures and pains which the partisans of pure automatism so strenuously deny.

Probability and circumstantial evidence thus run dead against the theory that our actions are purely mechanical in their causation. From the point of view of descriptive Psychology (even though we be bound to assume, as on p. 6, that all our feelings have brain-processes for their condition of existence, and can be remotely traced in every instance to currents coming from the outer world) we have no clear reason to doubt that the feelings may react so as to further or to dampen the processes to which they are due. I shall therefore not hesitate in the course of this book to use the language of common-sense. I shall talk as if consciousness kept actively pressing the nerve-centres in the direction of its own ends, and was no mere impotent and paralytic spectator of life's game.

The Localization of Functions in the Hemispheres.—The hemispheres, we lately said, must be the organ of memory, and in some way retain vestiges of former currents, by means of which mental considerations drawn from the past may be aroused before action takes place. The vivisections of physiologists and the observations of physicians have of late years given a concrete confirmation to this notion which the first rough appearances suggest. The various convolutions have had special functions assigned to them in relation to this and that sense-organ, as well as to this or that portion of the muscular system. This book is{105} no place for going over the evidence in detail, so I will simply indicate the conclusions which are most probable at the date of writing.

Mental and Cerebral Elements.—In the first place, there is a very neat parallelism between the analysis of brain-functions by the physiologists and that of mental functions by the 'analytic' psychologists.

The phrenological brain-doctrine divided the brain into 'organs,' each of which stood for the man in a certain partial attitude. The organ of 'Philoprogenitiveness,' with its concomitant consciousness, is an entire man so far as he loves children, that of 'Reverence' is an entire man worshipping, etc. The spiritualistic psychology, in turn, divided the Mind into 'faculties,' which were also entire mental men in certain limited attitudes. But 'faculties' are not mental elements any more than 'organs' are brain-elements. Analysis breaks both into more elementary constituents.

Brain and mind alike consist of simple elements, sensory and motor. "All nervous centres," says Dr. Hughlings Jackson, "from the lowest to the very highest (the substrata of consciousness), are made up of nothing else than nervous arrangements, representing impressions and movements.... I do not see of what other materials the brain can be made." Meynert represents the matter similarly when he calls the cortex of the hemispheres the surface of projection for every muscle and every sensitive point of the body. The muscles and the sensitive points are represented each by a cortical point, and the Brain is little more than the sum of all these cortical points, to which, on the mental side, as many sensations and ideas correspond. The sensations and ideas of sensation and of motion are, in turn, the elements out of which the Mind is built according to the analytic school of psychology. The relations between objects are explained by 'associations' between the ideas; and the emotional and instinctive tendencies, by associations between ideas and movements.{106} The same diagram can symbolize both the inner and the outer world; dots or circles standing indifferently for cells or ideas, and lines joining them, for fibres or associations. The associationist doctrine of 'ideas' may be doubted to be a literal expression of the truth, but it probably will always retain a didactic usefulness. At all events, it is interesting to see how well physiological analysis plays into its hands. To proceed to details.

The Motor Region.—The one thing which is perfectly well established is this, that the 'central' convolutions, on either side of the fissure of Rolando, and (at least in the monkey) the calloso-marginal convolution (which is continuous with them on the mesial surface where one hemisphere is applied against the other), form the region by which all the motor incitations which leave the cortex pass out, on their way to those executive centres in the region of the pons, medulla, and spinal cord from{107} which the muscular contractions are discharged in the last resort. The existence of this so-called 'motor zone' is established by anatomical as well as vivisectional and pathological evidence.

The accompanying figures (Figs. 41 and 42), from Schaefer and Horsley, show the topographical arrangement of the monkey's motor zone more clearly than any description.

Fig. 43, after Starr, shows how the fibres run downwards. All sensory currents entering the hemispheres run out from the Rolandic region, which may thus be regarded as a sort of funnel of escape, which narrows still more as it plunges beneath the surface, traversing the inner capsule, pons, and parts below. The dark ellipses on the left half of the diagram stand for hemorrhages or tumors, and the reader can easily trace, by following the course of the fibres, what the effect of them in interrupting motor currents may be.{108}

One of the most instructive proofs of motor localization in the cortex is that furnished by the disease now called aphemia, or motor aphasia. Motor aphasia is neither loss of voice nor paralysis of the tongue or lips. The patient's voice is as strong as ever, and all the innervations of his hypoglossal and facial nerves, except those necessary for speaking, may go on perfectly well. He can laugh and cry, and even sing; but he either is unable to utter any words at all; or a few meaningless stock phrases form his only speech; or else he speaks incoherently and confusedly,{109}

mispronouncing, misplacing, and misusing his words in various degrees. Sometimes his speech is a mere broth of unintelligible syllables. In cases of pure motor aphasia the patient recognizes his mistakes and suffers acutely from them. Now whenever a patient dies in such a condition as this, and an examination of his brain is permitted, it is found that the lowest frontal gyrus (see Fig. 44) is the seat of injury. Broca first noticed this fact in 1861, and since then the gyrus has gone by the name of Broca's convolution. The injury in right-handed people is found on the left hemisphere, and in left-handed people on the right hemisphere. Most people, in fact, are left-brained, that is, all their delicate and specialized movements are handed over to the charge of the left hemisphere. The ordinary right-handedness for such movements is only a consequence of that fact, a consequence which shows outwardly{110} on account of that extensive crossing of the fibres from the left hemisphere to the right half of the body only, which is shown in Fig. 41, below the letter M. But the left-brainedness might exist and not show outwardly. This would happen wherever organs on both sides of the body could be governed by the left hemisphere; and just such a case seems offered by the vocal organs, in that highly delicate and special motor service which we call speech. Either hemisphere can innervate them bilaterally, just as either seems able to innervate bilaterally the muscles of the trunk, ribs, and diaphragm. Of the special movements of speech, however, it would appear (from these very facts of aphasia) that the left hemisphere in most persons habitually takes exclusive charge. With that hemisphere thrown out of gear, speech is undone; even though the opposite hemisphere still be there for the performance of less specialized acts, such as the various movements required in eating.

The visual centre is in the occipital lobes. This also is proved by all the three kinds of possible evidence. It seems that the fibres from the left halves of both retinæ go to the left hemisphere, those from the right half to the right hemisphere. The consequence is that when the right occipital lobe, for example, is injured, 'hemianopsia' results in both eyes, that is, both retinæ grow blind as to their right halves, and the patient loses the leftward half of his field of view. The diagram on p. 111 will make this matter clear (see Fig. 45).

Quite recently, both Schaefer and Munk, in studying the movements of the eyeball produced by galvanizing the visual cortex in monkeys and dogs, have found reason to plot out an analogous correspondence between the upper and lower portions of the retinæ and certain parts of the visual cortex. If both occipital lobes were destroyed, we should have double hemiopia, or, in other words, total blindness. In human hemiopic blindness there is insensibility to light on one half of the field of view, but{111}

mental images of visible things remain. In double hemiopia there is every reason to believe that not only the sensation of light must go, but that all memories and images{112} of a visual order must be annihilated also. The man loses his visual 'ideas.' Only 'cortical' blindness can produce this effect on the ideas. Destruction of the retinæ or of the visual tracts anywhere between the cortex and the eyes impairs the retinal sensibility to light, but not the power of visual imagination.

Mental Blindness.—A most interesting effect of cortical disorder is mental blindness. This consists not so much in insensibility to optical impressions, as in inability to understand them. Psychologically it is interpretable as loss of associations between optical sensations and what they signify; and any interruption of the paths between the optic centres and the centres for other ideas ought to bring it about. Thus, printed letters of the alphabet, or words, signify both certain sounds and certain articulatory movements. But the connection between the articulating or auditory centres and those for sight being ruptured, we ought a priori to expect that the sight of words would{113} fail to awaken the idea of their sound, or of the movement for pronouncing them. We ought, in short, to have alexia, or inability to read: and this is just what we do have as a complication of aphasic disease in many cases of extensive injury about the fronto-temporal regions.

Where an object fails to be recognized by sight, it often happens that the patient will recognize and name it as soon as he touches it with his hand. This shows in an interesting way how numerous are the incoming paths which all end by running out of the brain through the channel of speech. The hand-path is open, though the eye-path be closed. When mental blindness is most complete, neither sight, touch, nor sound avails to steer the patient, and a sort of dementia which has been called asymbolia or apraxia is the result. The commonest articles are not understood. The patient will put his breeches on one shoulder and his hat upon the other, will bite into the soap and lay his shoes on the table, or take his food into his hand and throw it down again, not knowing what to do with it, etc. Such disorder can only come from extensive brain-injury.

The centre for hearing is situated in man in the upper convolution of the temporal lobe (see the part marked 'Wernicke' in Fig. 44). The phenomena of aphasia show this. We studied motor aphasia a few pages back; we must now consider sensory aphasia. Our knowledge of aphasia has had three stages: we may talk of the period of Broca, the period of Wernicke, and the period of Charcot. What Broca's discovery was we have seen. Wernicke was the first to discriminate those cases in which the patient can not even understand speech from those in which he can understand, only not talk; and to ascribe the former condition to lesion of the temporal lobe. The condition in question is word-deafness, and the disease is auditory aphasia. The latest statistical survey of the subject is that by Dr. Allen Starr. In the seven cases of pure word-deafness which he has collected (cases in{114} which the patient could read, talk, and write, but not understand what was said to him), the lesion was limited to the first and second temporal convolutions in their posterior two thirds. The lesion (in right-handed, i.e. left-brained, persons) is always on the left side, like the lesion in motor aphasia. Crude hearing would not be abolished, even were the left centre for it utterly destroyed; the right centre would still provide for that. But the linguistic use of hearing appears bound up with the integrity of the left centre more or less exclusively. Here it must be that words heard enter into association with the things which they represent, on the one hand, and with the movements necessary for pronouncing them, on the other. In most of us (as Wernicke said) speech must go on from auditory cues; that is, our visual, tactile, and other ideas probably do not innervate our motor centres directly, but only after first arousing the mental sound of the words. This is the immediate stimulus to articulation; and where the possibility of this is abolished by the destruction of its usual channel in the left temporal lobe, the articulation must suffer. In the few cases in which the channel is abolished with no bad effect on speech we must suppose an idiosyncrasy. The patient must innervate his speech-organs either from the corresponding portion of the other hemisphere or directly from the centres of vision, touch, etc., without leaning on the auditory region. It is the minuter analysis of such individual differences as these which constitutes Charcot's contribution towards clearing up the subject.

Every namable thing has numerous properties, qualities, or aspects. In our minds the properties together with the name form an associated group. If different parts of the brain are severally concerned with the several properties, and a farther part with the hearing, and still another with the uttering, of the name, there must inevitably be brought about (through the law of association which we shall later study) such a connection amongst all these brain-parts that the activity of any one of them will be likely to{115} awaken the activity of all the rest. When we are talking whilst we think, the ultimate process is utterance. If the brain-part for that be injured, speech is impossible or disorderly, even though all the other brain-parts be intact: and this is just the condition of things which, on p. 109, we found to be brought about by lesion of the convolution of Broca. But back of that last act various orders of succession are possible in the associations of a talking man's ideas. The more usual order is, as aforesaid, from the tactile, visual, or other properties of the things thought-about to the sound of their names, and then to the latter's utterance. But if in a certain individual's mind the look of an object or the look of its name be what habitually precedes articulation, then the loss of the hearing centre will pro tanto not affect that individual's speech or reading. He will be mentally deaf, i.e. his understanding of the human voice will suffer, but he will not be aphasic. In this way it is possible to explain the seven cases of word-deafness without motor aphasia which figure in Dr. Starr's table.

If this order of association be ingrained and habitual in that individual, injury to his visual centres will make him not only word-blind, but aphasic as well. His speech will become confused in consequence of an occipital lesion. Naunyn, consequently, plotting out on a diagram of the hemisphere the 71 irreproachably reported cases of aphasia which he was able to collect, finds that the lesions concentrate themselves in three places: first, on Broca's centre; second, on Wernicke's; third, on the supra-marginal and angular convolutions under which those fibres pass which connect the visual centres with the rest of the brain (see Fig. 47, p. 116). With this result Dr. Starr's analysis of purely sensory cases agrees.

In the chapter on Imagination we shall return to these differences in the sensory spheres of different individuals. Meanwhile few things show more beautifully than the history of our knowledge of aphasia how the sagacity and patience of many banded workers are in time certain to{116} analyze the darkest confusion into an orderly display. There is no 'organ' of Speech in the brain any more than there is a 'faculty' of Speech in the mind. The entire mind and the entire brain are more or less at work in a man who uses language. The subjoined diagram, from Ross, shows the four parts most vitally concerned, and, in the light of our text, needs no farther explanation (see Fig. 48, p. 117).

Centres for Smell, Taste, and Touch.—The other sensory centres are less definitely made out. Of smell and taste I will say nothing; and of muscular and cutaneous feeling only this, that it seems most probably seated in the motor zone, and possibly in the convolutions immediately backwards and midwards thereof. The incoming tactile currents must enter the cells of this region by one set of fibres, and the discharges leave them by another, but of these{117}

Conclusion.—We thus see the postulate of Meynert and Jackson, with which we started on p. 105, to be on the whole most satisfactorily corroborated by objective research. The highest centres do probably contain nothing but arrangements for representing impressions and movements, and other arrangements for coupling the activity of these arrangements together. Currents pouring in from the sense-organs first excite some arrangements, which in turn excite others, until at last a discharge downwards of some sort occurs. When this is once clearly grasped there remains little ground for asking whether the motor zone is exclusively motor, or sensitive as well. The whole cortex, inasmuch as{118} currents run through it, is both. All the currents probably have feelings going with them, and sooner or later bring movements about. In one aspect, then, every centre is afferent, in another efferent, even the motor cells of the spinal cord having these two aspects inseparably conjoined. Marique, and Exner and Paneth have shown that by cutting round a 'motor' centre and so separating it from the influence of the rest of the cortex, the same disorders are produced as by cutting it out, so that it is really just what I called it, only the funnel through which the stream of innervation, starting from elsewhere, escapes; consciousness accompanying the stream, and being mainly of things seen if the stream is strongest occipitally, of things heard if it is strongest temporally, of things felt, etc., if the stream occupies most intensely the 'motor zone.' It seems to me that some broad and vague formulation like this is as much as we can safely venture on in the present state of science—so much at least is not likely to be overturned. But it is obvious how little this tells us of the detail of what goes on in the brain when a certain thought is before the mind. The general forms of relation perceived between things, as their identities, likenesses, or contrasts; the forms of the consciousness itself, as effortless or perplexed, attentive or inattentive, pleasant or disagreeable; the phenomena of interest and selection, etc., etc., are all lumped together as effects correlated with the currents that connect one centre with another. Nothing can be more vague than such a formula. Moreover certain portions of the brain, as the lower frontal lobes, escape formulational together. Their destruction gives rise to no local trouble of either motion or sensibility in dogs, and in monkeys neither stimulation nor excision of these lobes produces any symptoms whatever. One monkey of Horsley and Schaefer's was as tame, and did certain tricks as well, after as before the operation.

It is in short obvious that our knowledge of our mental states infinitely exceeds our knowledge of their concomitant cerebral conditions. Without introspective analysis of{119} the mental elements of speech, the doctrine of Aphasia, for instance, which is the most brilliant jewel in Physiology, would have been utterly impossible. Our assumption, therefore (p. 5), that mind-states are absolutely dependent on brain-conditions, must still be understood as a mere postulate. We may have a general faith that it must be true, but any exact insight as to how it is true lags wofully behind.

Before taking up the study of conscious states properly so called, I will in a separate chapter speak of two or three aspects of brain-function which have a general importance and which coöperate in the production of all our mental states.{120}

The Nervous Discharge.—The word discharge is constantly used, and must be used in this book, to designate the escape of a current downwards into muscles or other internal organs. The reader must not understand the word figuratively. From the point of view of dynamics the passage of a current out of a motor cell is probably altogether analogous to the explosion of a gun. The matter of the cell is in a state of internal tension, which the incoming current resolves, tumbling the molecules into a more stable equilibrium and liberating an amount of energy which starts the current of the outgoing fibre. This current is stronger than that of the incoming fibre. When it reaches the muscle it produces an analogous disintegration of pent-up molecules and the result is a stronger effect still. Matteuci found that the work done by a muscle's contraction was 27,000 times greater than that done by the galvanic current which stimulated its motor nerve. When a frog's leg-muscle is made to contract, first directly, by stimulation of its motor nerve, and second reflexly, by stimulation of a sensory nerve, it is found that the reflex way requires a stronger current and is more tardy, but that the contraction is stronger when it does occur. These facts prove that the cells in the spinal cord through which the reflex takes place offer a resistance which has first to be overcome, but that a relatively violent outward current outwards then escapes from them. What is this but an explosive discharge on a minute scale?

Reaction-time.—The measurement of the time required for the discharge is one of the lines of experimental investigation{121} most diligently followed of late years. Helmholtz led the way by discovering the rapidity of the outgoing current in the sciatic nerve of the frog. The methods he used were soon applied to sensory reactions, and the results caused much popular admiration when described as measurements of the 'velocity of thought.' The phrase 'quick as thought' had from time immemorial signified all that was wonderful and elusive of determination in the line of speed; and the way in which Science laid her doomful hand upon this mystery reminded people of the day when Franklin first 'eripuit cœlo fulmen,' foreshadowing the reign of a newer and colder race of gods. I may say, however, immediately, that the phrase 'velocity of thought' is misleading, for it is by no means clear in any of the cases what particular act of thought occurs during the time which is measured. What the times in question really represent is the total duration of certain reactions upon stimuli. Certain of the conditions of the reaction are prepared beforehand; they consist in the assumption of those motor and sensory tensions which we name the expectant state. Just what happens during the actual time occupied by the reaction (in other words, just what is added to the preëxistent tensions to produce the actual discharge) is not made out at present, either from the neural or from the mental point of view.

The method is essentially the same in all these investigations. A signal of some sort is communicated to the subject, and at the same instant records itself on a time-registering apparatus. The subject then makes a muscular movement of some sort, which is the 'reaction,' and which also records itself automatically. The time found to have elapsed between the two records is the total time of that reaction. The time-registering instruments are of various types. One type is that of the revolving drum covered with smoked paper, on which one electric pen traces a line which the signal breaks and the 'reaction' draws again; whilst another electric pen (connected with a rod of metal{122} vibrating at a known rate) traces alongside of the former line a 'time-line' of which each undulation or link stands for a certain fraction of a second, and against which the break in the reaction-line can be measured. Compare Fig. 49, where the line is broken by the signal at the first arrow, and continued again by the reaction at the second. The machine most often used is Hipp's chronoscopic clock. The hands are placed at zero, the signal starts them (by an electric connection), and the reaction stops them. The duration of their movement, down to 1000ths of a second, is then read off from the dial-plates.

Simple Reactions.—It is found that the reaction-time differs in the same person according to the direction of his expectant attention. If he thinks as little as possible of the movement which he is to make, and concentrates his mind upon the signal to be received, it is longer; if, on the contrary, he bends his mind exclusively upon the muscular response, it is shorter. Lange, who first noticed this fact when working in Wundt's laboratory, found his own 'muscular' reaction-time to average 0´´.123, whilst his 'sensorial' reaction-time averaged as much as 0´´.230. It is obvious that experiments, to have any comparative value, must always be made according to the 'muscular' method, which reduces the figure to its minimum and makes it more constant. In general it lies between one and two tenths of a second. It seems to me that under these circumstances the reaction is essentially a reflex act. The preliminary making-ready of the muscles for the movement{123} means the excitement of the paths of discharge to a point just short of actual discharge before the signal comes in. In other words, it means the temporary formation of a real 'reflex-arc' in the centres, through which the incoming current instantly can pour out again. But when, on the other hand, the expectant attention is exclusively addressed to the signal, the excitement of the motor tracts can only begin after this latter has come in, and under this condition the reaction takes more time. In the hair-trigger condition in which we stand when making reactions by the 'muscular' method, we sometimes respond to a wrong signal, especially if it be of the same kind with the one we expect. The signal is but the spark which touches off a train already laid. There is no thought in the matter; the hand jerks by an involuntary start.

These experiments are thus in no sense measurements of the swiftness of thought. Only when we complicate them is there a chance for anything like an intellectual operation to occur. They may be complicated in various ways. The reaction may be withheld until the signal has consciously awakened a distinct idea (Wundt's discrimination-time, association-time), and may then be performed. Or there may be a variety of possible signals, each with a different reaction assigned to it, and the reacter may be uncertain which one he is about to receive. The reaction would then hardly seem to occur without a preliminary recognition and choice. Even here, however, the discrimination and choice are widely different from the intellectual operations of which we are ordinarily conscious under those names. Meanwhile the simple reaction-time remains as the starting point of all these superinduced complications, and its own variations must be briefly passed in review.

The reaction-time varies with the individual and his age. Old and uncultivated people have it long (nearly a second, in an old pauper observed by Exner). Children have it long (half a second, according to Herzen).

Practice shortens it to a quantity which is for each individual{124} a minimum beyond which no farther reduction can be made. The aforesaid old pauper's time was, after much practice, reduced to 0.1866 sec.

Fatigue lengthens it, and concentration of attention shortens it. The nature of the signal makes it vary. I here bring together the averages which have been obtained by some observers:

It will be observed that sound is more promptly reacted on than either sight or touch. Taste and smell are slower than either. The intensity of the signal makes a difference. The intenser the stimulus the shorter the time. Herzen compared the reaction from a corn on the toe with that from the skin of the hand of the same subject. The two places were stimulated simultaneously, and the subject tried to react simultaneously with both hand and foot, but the foot always went quickest. When the sound skin of the foot was touched instead of the corn, it was the hand which always reacted first. Intoxicants on the whole lengthen the time, but much depends on the dose.

Complicated Reactions.—These occur when some kind of intellectual operation accompanies the reaction. The rational place in which to report of them would be under the head of the various intellectual operations concerned. But certain persons prefer to see all these measurements bunched together regardless of context; so, to meet their views, I give the complicated reactions here.

When we have to think before reacting it is obvious that there is no definite reaction-time of which we can talk—it all depends on how long we think. The only times we can measure are the minimum times of certain determinate and very simple intellectual operations. The time required for discrimination has thus been made a subject of experimental measurement. Wundt calls it Unterscheidungszeit.{125} His subjects (whose simple reaction-time had previously been determined) were required to make a movement, always the same, the instant they discerned which of two or more signals they received. The excess of time occupied by these reactions over the simple reaction-time, in which only one signal was used and known in advance, measured, according to Wundt, the time required for the act of discrimination. It was found longer when four different signals were irregularly used than when only two were used. When two were used (the signals being the sudden appearance of a black or of a white object), the average times of three observers were respectively (in seconds)

When four signals were used, a red and a green light being added to the others, it became, for the same observers,

Prof. Cattell found he could get no results by this method, and reverted to one used by observers previous to Wundt and which Wundt had rejected. This is the einfache Wahlmethode, as Wundt calls it. The reacter awaits the signal and reacts if it is of one sort, but omits to act if it is of another sort. The reaction thus occurs after discrimination; the motor impulse cannot be sent to the hand until the subject knows what the signal is. Reacting in this way, Prof. Cattell found the increment of time required for distinguishing a white signal from no signal to be, in two observers,

that for distinguishing one color from another was similarly

that for distinguishing a certain color from ten other colors,

that for distinguishing the letter A in ordinary print from the letter Z,

{126}

that for distinguishing a given letter from all the rest of the alphabet (not reacting until that letter appeared),

that for distinguishing a word from any of twenty-five other words, from

—the difference depending on the length of the words and the familiarity of the language to which they belonged.

Prof. Cattell calls attention to the fact that the time for distinguishing a word is often but little more than that for distinguishing a letter: "We do not, therefore," he says, "distinguish separately the letters of which a word is composed, but the word as a whole. The application of this in teaching children to read is evident."

He also finds a great difference in the time with which various letters are distinguished, E being particularly bad.

The time required for association of one idea with another has been measured. Gallon, using a very simple apparatus, found that the sight of an unforeseen word would awaken an associated 'idea' in about ⅚ of a second. Wundt next made determinations in which the 'cue' was given by single-syllabled words called out by an assistant. The person experimented on had to press a key as soon as the sound of the word awakened an associated idea. Both word and reaction were chronographically registered, and the total time-interval between the two amounted, in four observers, to 1.009, 0.896, 1.037, and 1.154 seconds respectively. From this the simple reaction-time and the time of merely identifying the word's sound (the 'apperception-time,' as Wundt calls it) must be subtracted, to get the exact time required for the associated idea to arise. These times were separately determined and subtracted. The difference, called by Wundt association-time, amounted, in the same four persons, to 706, 723, 752, and 874 thousandths of a second respectively. The length of the last figure is due to the fact that the person reacting was an American, whose associations with German words would naturally be{127} slower than those of natives. The shortest association-time noted was when the word 'Sturm' suggested to Wundt the word 'Wind' in 0.341 second. Prof. Cattell made some interesting observations upon the association-time between the look of letters and their names. "I pasted letters," he says, "on a revolving drum, and determined at what rate they could be read aloud as they passed by a slit in a screen." He found it to vary according as one, or more than one, letter was visible at a time through the slit, and gives half a second as about the time which it takes to see and name a single letter seen alone. The rapidity of a man's reading is of course a measure of that of his associations, since each seen word must call up its name, at least, ere it is read. "I find," says Prof. Cattell, "that it takes about twice as long to read (aloud, as fast as possible) words which have no connection, as words which make sentences, and letters which have no connection, as letters which make words. When the words make sentences and the letters words, not only do the processes of seeing and naming overlap, but by one mental effort the subject can recognize a whole group of words or letters, and by one will-act choose the motions to be made in naming, so that the rate at which the words and letters are read is really only limited by the maximum rapidity at which the speech-organs can be moved.... For example, when reading as fast as possible the writer's rate was, English 138, French 167, German 250, Italian 327, Latin 434, and Greek 484; the figures giving the thousandths of a second taken to read each word. Experiments made on others strikingly confirm these results. The subject does not know that he is reading the foreign language more slowly than his own; this explains why foreigners seem to talk so fast....

"The time required to see and name colors and pictures of objects was determined in the same way. The time was found to be about the same (over ½ sec.) for colors as for pictures, and about twice as long as for words and letters. Other experiments I have made show that we can recognize{128} a single color or picture in a slightly shorter time than a word or letter, but take longer to name it. This is because, in the case of words and letters, the association between the idea and the name has taken place so often that the process has become automatic, whereas in the case of colors and pictures we must by a voluntary effort choose the name."

Dr. Romanes has found "astonishing differences in the maximum rate of reading which is possible to different individuals, all of whom have been accustomed to extensive reading. That is to say, the difference may amount to 4 to 1; or, otherwise stated, in a given time one individual may be able to read four times as much as another. Moreover, it appeared that there was no relationship between slowness of reading and power of assimilation; on the contrary, when all the efforts are directed to assimilating as much as possible in a given time, the rapid readers (as shown by their written notes) usually give a better account of the portions of the paragraph which have been compassed by the slow readers than the latter are able to give; and the most rapid reader I have found is also the best at assimilating. I should further say," Dr. R. continues, "that there is no relationship between rapidity of perception as thus tested and intellectual activity as tested by the general results of intellectual work; for I have tried the experiment with several highly distinguished men in science and literature, most of whom I found to be slow readers."

The degree of concentration of the attention has much to do with determining the reaction-time. Anything which baffles or distracts us beforehand, or startles us in the signal, makes the time proportionally long.

The Summation of Stimuli.—Throughout the nerve-centres it is a law that a stimulus which would be inadequate by itself to excite a nerve-centre to effective discharge may, by acting with one or more other stimuli (equally ineffectual by themselves alone) bring the discharge about.{129} The natural way to consider this is as a summation of tensions which at last overcome a resistance. The first of them produce a 'latent excitement' or a 'heightened irritability'—the phrase is immaterial so far as practical consequences go;—the last is the straw which breaks the camel's back.

This is proved by many physiological experiments which cannot here be detailed; but outside of the laboratory we constantly apply the law of summation in our practical appeals. If a car-horse balks, the final way of starting him is by applying a number of customary incitements at once. If the driver uses reins and voice, if one bystander pulls at his head, another lashes his hind-quarters, the conductor rings the bell, and the dismounted passengers shove the car, all at the same moment, his obstinacy generally yields, and he goes on his way rejoicing. If we are striving to remember a lost name or fact, we think of as many 'cues' as possible, so that by their joint action they may recall what no one of them can recall alone. The sight of a dead prey will often not stimulate a beast to pursuit, but if the sight of movement be added to that of form, pursuit occurs. "Brücke noted that his brainless hen which made no attempt to peck at the grain under her very eyes, began pecking if the grain were thrown on the ground with force, so as to produce a rattling sound." "Dr. Allen Thomson hatched out some chickens on a carpet, where he kept them for several days. They showed no inclination to scrape, ... but when Dr. Thomson sprinkled a little gravel on the carpet, ... the chickens immediately began their scraping movements." A strange person, and darkness, are both of them stimuli to fear and mistrust in dogs (and for the matter of that, in men). Neither circumstance alone may awaken outward manifestations, but together, i.e. when the strange man is met in the dark, the dog will be excited to violent defiance. Street hawkers well know the efficacy of summation, for they arrange themselves in a line on the sidewalk, and{130} the passer often buys from the last one of them, through the effect of the reiterated solicitation, what he refused to buy from the first in the row.

Cerebral Blood-supply.—All parts of the cortex, when electrically excited, produce alterations both of respiration and circulation. The blood-pressure somewhat rises, as a rule, all over the body, no matter where the cortical irritation is applied, though the motor zone is the most sensitive region for the purpose. Slowing and quickening of the heart are also observed. Mosso, using his 'plethysmograph' as an indicator, discovered that the blood-supply to the arms diminished during intellectual activity, and found furthermore that the arterial tension (as shown by the sphygmograph) was increased in these members (see Fig. 50). So slight an emotion as that produced by the entrance of Professor Ludwig into the laboratory was instantly followed by a shrinkage of the arms. The brain itself is an excessively vascular organ, a sponge full of blood, in fact; and another of Mosso's inventions showed that when less blood went to the legs, more went to the head. The subject to be observed lay on a delicately balanced table which could tip downward either at the head or at the foot if the weight of either end were increased. The moment emotional or intellectual activity began in the subject, down went the head-end, in consequence of the redistribution of blood in his system. But the best proof of the immediate afflux of blood to the brain during mental activity is due to Mosso's observations on three persons whose brain had been laid bare by lesion of the skull.{131} By means of apparatus described in his book, this physiologist was enabled to let the brain-pulse record itself directly by a tracing. The intra-cranial blood-pressure rose immediately whenever the subject was spoken to, or when he began to think actively, as in solving a problem in mental arithmetic. Mosso gives in his work a large number of reproductions of tracings which show the instantaneity of the change of blood-supply, whenever the mental activity was quickened by any cause whatever, intellectual or emotional. He relates of his female subject that one day whilst tracing her brain-pulse he observed a sudden rise with no apparent outer or inner cause. She however confessed to him afterwards that at that moment she had caught sight of a skull on top of a piece of furniture in the room, and that this had given her a slight emotion.

Cerebral Thermometry.—Brain-activity seems accompanied by a local disengagement of heat. The earliest careful work in this direction was by Dr. J. S. Lombard in 1867. He noted the changes in delicate thermometers and electric piles placed against the scalp in human beings, and found that any intellectual effort, such as computing, composing, reciting poetry silently or aloud, and especially that emotional excitement such as an angry fit, caused a general rise of temperature, which rarely exceeded a degree Fahrenheit. In 1870 the indefatigable Schiff took up the subject, experimenting on live dogs and chickens by plunging thermo-electric needles into the substance of their brain. After habituation was established, he tested the animals with various sensations, tactile, optic, olfactory, and auditory. He found very regularly an abrupt alteration of the intra-cerebral temperature. When, for instance, he presented an empty roll of paper to the nose of his dog as it lay motionless, there was a small deflection, but when a piece of meat was in the paper the deflection was much greater. Schiff concluded from these and other experiments that sensorial activity heats the brain-tissue, but he did not try to localize the increment of heat beyond finding{132} that it was in both hemispheres, whatever might be the sensation applied. Dr. Amidon in 1880 made a farther step forward, in localizing the heat produced by voluntary muscular contractions. Applying a number of delicate surface-thermometers simultaneously against the scalp, he found that when different muscles of the body were made to contract vigorously for ten minutes or more, different regions of the scalp rose in temperature, that the regions were well focalized, and that the rise of temperature was often considerably over a Fahrenheit degree. To a large extent these regions correspond to the centres for the same movements assigned by Ferrier and others on other grounds; only they cover more of the skull.

Phosphorus and Thought.—Considering the large amount of popular nonsense which passes current on this subject I may be pardoned for a brief mention of it here. 'Ohne Phosphor, kein Gedanke,' was a noted war-cry of the 'materialists' during the excitement on that subject which filled Germany in the '60s. The brain, like every other organ of the body, contains phosphorus, and a score of other chemicals besides. Why the phosphorus should be picked out as its essence, no one knows. It would be equally true to say, 'Ohne Wasser, kein Gedanke,' or 'Ohne Kochsalz, kein Gedanke'; for thought would stop as quickly if the brain should dry up or lose its NaCl as if it lost its phosphorus. In America the phosphorus-delusion has twined itself round a saying quoted (rightly or wrongly) from Professor L. Agassiz, to the effect that fishermen are more intelligent than farmers because they eat so much fish, which contains so much phosphorus. All the alleged facts may be doubted.

The only straight way to ascertain the importance of phosphorus to thought would be to find whether more is excreted by the brain during mental activity than during rest. Unfortunately we cannot do this directly, but can only gauge the amount of PO₅ in the urine, and this procedure has been adopted by a variety of observers, some of{133} whom found the phosphates in the urine diminished, whilst others found them increased, by intellectual work. On the whole, it is impossible to trace any constant relation. In maniacal excitement less phosphorus than usual seems to be excreted. More is excreted during sleep. The fact that phosphorus-preparations may do good in nervous exhaustion proves nothing as to the part played by phosphorus in mental activity. Like iron, arsenic, and other remedies it is a stimulant or tonic, of whose intimate workings in the system we know absolutely nothing, and which moreover does good in an extremely small number of the cases in which it is prescribed.

The phosphorus-philosophers have often compared thought to a secretion. "The brain secretes thought, as the kidneys secrete urine, or as the liver secretes bile," are phrases which one sometimes hears. The lame analogy need hardly be pointed out. The materials which the brain pours into the blood (cholesterin, creatin, xanthin, or whatever they may be) are the analogues of the urine and the bile, being in fact real material excreta. As far as these matters go, the brain is a ductless gland. But we know of nothing connected with liver-and kidney-activity which can be in the remotest degree compared with the stream of thought that accompanies the brain's material secretions.{134}

Its Importance for Psychology.—There remains a condition of general neural activity so important as to deserve a chapter by itself—I refer to the aptitude of the nerve-centres, especially of the hemispheres, for acquiring habits. An acquired habit, from the physiological point of view, is nothing but a new pathway of discharge formed in the brain, by which certain incoming currents ever after tend to escape. That is the thesis of this chapter; and we shall see in the later and more psychological chapters that such functions as the association of ideas, perception, memory, reasoning, the education of the will, etc., etc., can best be understood as results of the formation de novo of just such pathways of discharge.

Habit has a physical basis. The moment one tries to define what habit is, one is led to the fundamental properties of matter. The laws of Nature are nothing but the immutable habits which the different elementary sorts of matter follow in their actions and reactions upon each other. In the organic world, however, the habits are more variable than this. Even instincts vary from one individual to another of a kind; and are modified in the same individual, as we shall later see, to suit the exigencies of the case. On the principles of the atomistic philosophy the habits of an elementary particle of matter cannot change, because the particle is itself an unchangeable thing; but those of a compound mass of matter can change, because they are in the last instance due to the structure of the compound, and either outward forces or inward tensions can, from one hour to another, turn that structure{135} into something different from what it was. That is, they can do so if the body be plastic enough to maintain its integrity, and be not disrupted when its structure yields. The change of structure here spoken of need not involve the outward shape; it may be invisible and molecular, as when a bar of iron becomes magnetic or crystalline through the action of certain outward causes, or india-rubber becomes friable, or plaster 'sets.' All these changes are rather slow; the material in question opposes a certain resistance to the modifying cause, which it takes time to overcome, but the gradual yielding whereof often saves the material from being disintegrated altogether. When the structure has yielded, the same inertia becomes a condition of its comparative permanence in the new form, and of the new habits the body then manifests. Plasticity, then, in the wide sense of the word, means the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once. Each relatively stable phase of equilibrium in such a structure is marked by what we may call a new set of habits. Organic matter, especially nervous tissue, seems endowed with a very extraordinary degree of plasticity of this sort; so that we may without hesitation lay down as our first proposition the following: that the phenomena of habit in living beings are due to the plasticity of the organic materials of which their bodies are composed.

The philosophy of habit is thus, in the first instance, a chapter in physics rather than in physiology or psychology. That it is at bottom a physical principle, is admitted by all good recent writers on the subject. They call attention to analogues of acquired habits exhibited by dead matter. Thus, M. Léon Dumont writes:

"Every one knows how a garment, after having been worn a certain time, clings to the shape of the body better than when it was new; there has been a change in the tissue, and this change is a new habit of cohesion. A lock works better after being used some time; at the outset more{136} force was required to overcome certain roughness in the mechanism. The overcoming of their resistance is a phenomenon of habituation. It costs less trouble to fold a paper when it has been folded already; ... and just so in the nervous system the impressions of outer objects fashion for themselves more and more appropriate paths, and these vital phenomena recur under similar excitements from without, when they have been interrupted a certain time."

Not in the nervous system alone. A scar anywhere is a locus minoris resistentiæ, more liable to be abraded, inflamed, to suffer pain and cold, than are the neighboring parts. A sprained ankle, a dislocated arm, are in danger of being sprained or dislocated again; joints that have once been attacked by rheumatism or gout, mucous membranes that have been the seat of catarrh, are with each fresh recurrence more prone to a relapse, until often the morbid state chronically substitutes itself for the sound one. And in the nervous system itself it is well known how many so-called functional diseases seem to keep themselves going simply because they happen to have once begun; and how the forcible cutting short by medicine of a few attacks is often sufficient to enable the physiological forces to get possession of the field again, and to bring the organs back to functions of health. Epilepsies, neuralgias, convulsive affections of various sorts, insomnias, are so many cases in point. And, to take what are more obviously habits, the success with which a 'weaning' treatment can often be applied to the victims of unhealthy indulgence of passion, or of mere complaining or irascible disposition, shows us how much the morbid manifestations themselves were due to the mere inertia of the nervous organs, when once launched on a false career.

Habits are due to pathways through the nerve-centres. If habits are due to the plasticity of materials to outward agents, we can immediately see to what outward influences, if to any, the brain-matter is plastic. Not to mechanical pressures, not to thermal changes, not to any of the forces{137} to which all the other organs of our body are exposed; for, as we saw on pp. 9-10, Nature has so blanketed and wrapped the brain about that the only impressions that can be made upon it are through the blood, on the one hand, and the sensory nerve-roots, on the other; and it is to the infinitely attenuated currents that pour in through these latter channels that the hemispherical cortex shows itself to be so peculiarly susceptible. The currents, once in, must find a way out. In getting out they leave their traces in the paths which they take. The only thing they can do, in short, is to deepen old paths or to make new ones; and the whole plasticity of the brain sums itself up in two words when we call it an organ in which currents pouring in from the sense-organs make with extreme facility paths which do not easily disappear. For, of course, a simple habit, like every other nervous event—the habit of snuffling, for example, or of putting one's hands into one's pockets, or of biting one's nails—is, mechanically, nothing but a reflex discharge; and its anatomical substratum must be a path in the system. The most complex habits, as we shall presently see more fully, are, from the same point of view, nothing but concatenated discharges in the nerve-centres, due to the presence there of systems of reflex paths, so organized as to wake each other up successively—the impression produced by one muscular contraction serving as a stimulus to provoke the next, until a final impression inhibits the process and closes the chain.

It must be noticed that the growth of structural modification in living matter may be more rapid than in any lifeless mass, because the incessant nutritive renovation of which the living matter is the seat tends often to corroborate and fix the impressed modification, rather than to counteract it by renewing the original constitution of the tissue that has been impressed. Thus, we notice after exercising our muscles or our brain in a new way, that we can do so no longer at that time; but after a day or two of rest, when we resume the discipline, our increase in skill{138} not seldom surprises us. I have often noticed this in learning a tune; and it has led a German author to say that we learn to swim during the winter, and to skate during the summer.

Practical Effects of Habit.—First, habit simplifies our movements, makes them accurate, and diminishes fatigue.

Man is born with a tendency to do more things than he has ready-made arrangements for in his nerve-centres. Most of the performances of other animals are automatic. But in him the number of them is so enormous that most of them must be the fruit of painful study. If practice did not make perfect, nor habit economize the expense of nervous and muscular energy, he would be in a sorry plight. As Dr. Maudsley says:[30]

"If an act became no easier after being done several times, if the careful direction of consciousness were necessary to its accomplishment on each occasion, it is evident that the whole activity of a lifetime might be confined to one or two deeds—that no progress could take place in development. A man might be occupied all day in dressing and undressing himself; the attitude of his body would absorb all his attention and energy; the washing of his hands or the fastening of a button would be as difficult to him on each occasion as to the child on its first trial; and he would, furthermore, be completely exhausted by his exertions. Think of the pains necessary to teach a child to stand, of the many efforts which it must make, and of the ease with which it at last stands, unconscious of any effort. For while secondarily-automatic acts are accomplished with comparatively little weariness—in this regard approaching the organic movements, or the original reflex movements—the conscious effort of the will soon produces exhaustion. A spinal cord without ... memory would simply be an idiotic spinal cord.... It is impossible for an individual{139} to realize how much he owes to its automatic agency until disease has impaired its functions."

Secondly, habit diminishes the conscious attention with which our acts are performed.

One may state this abstractly thus: If an act require for its execution a chain, A, B, C, D, E, F, G, etc., of successive nervous events, then in the first performances of the action the conscious will must choose each of these events from a number of wrong alternatives that tend to present themselves; but habit soon brings it about that each event calls up its own appropriate successor without any alternative offering itself, and without any reference to the conscious will, until at last the whole chain, A, B, C, D, E, F, G, rattles itself off as soon as A occurs, just as if A and the rest of the chain were fused into a continuous stream. Whilst we are learning to walk, to ride, to swim, skate, fence, write, play, or sing, we interrupt ourselves at every step by unnecessary movements and false notes. When we are proficients, on the contrary, the results follow not only with the very minimum of muscular action requisite to bring them forth, but they follow from a single instantaneous 'cue.' The marksman sees the bird, and, before he knows it, he has aimed and shot. A gleam in his adversary's eye, a momentary pressure from his rapier, and the fencer finds that he has instantly made the right parry and return. A glance at the musical hieroglyphics, and the pianist's fingers have rippled through a shower of notes. And not only is it the right thing at the right time that we thus involuntarily do, but the wrong thing also, if it be an habitual thing. Who is there that has never wound up his watch on taking off his waistcoat in the daytime, or taken his latch-key out on arriving at the door-step of a friend? Persons in going to their bedroom to dress for dinner have been known to take off one garment after another and finally to get into bed, merely because that was the habitual issue of the first few movements when performed at a later hour. We all have a{140} definite routine manner of performing certain daily offices connected with the toilet, with the opening and shutting of familiar cupboards, and the like. But our higher thought-centres know hardly anything about the matter. Few men can tell off-hand which sock, shoe, or trousers-leg they put on first. They must first mentally rehearse the act; and even that is often insufficient—the act must be performed. So of the questions, Which valve of the shutters opens first? Which way does my door swing? etc. I cannot tell the answer; yet my hand never makes a mistake. No one can describe the order in which he brushes his hair or teeth; yet it is likely that the order is a pretty fixed one in all of us.

These results may be expressed as follows:

In action grown habitual, what instigates each new muscular contraction to take place in its appointed order is not a thought or a perception, but the sensation occasioned by the muscular contraction just finished. A strictly voluntary act has to be guided by idea, perception, and volition, throughout its whole course. In habitual action, mere sensation is a sufficient guide, and the upper regions of brain and mind are set comparatively free. A diagram will make the matter clear:

Let A, B, C, D, E, F, G represent an habitual chain of muscular contractions, and let a, b, c, d, e, f stand for the several sensations which these contractions excite in us when they are successively performed. Such sensations{141} will usually be in the parts moved, but they may also be effects of the movement upon the eye or the ear. Through them, and through them alone, we are made aware whether or not the contraction has occurred. When the series, A, B, C, D, E, F, G, is being learned, each of these sensations becomes the object of a separate act of attention by the mind. We test each movement intellectually, to see if it have been rightly performed, before advancing to the next. We hesitate, compare, choose, revoke, reject, etc.; and the order by which the next movement is discharged is an express order from the ideational centres after this deliberation has been gone through.

In habitual action, on the contrary, the only impulse which the intellectual centres need send down is that which carries the command to start. This is represented in the diagram by V; it may be a thought of the first movement or of the last result, or a mere perception of some of the habitual conditions of the chain, the presence, e.g., of the keyboard near the hand. In the present example, no sooner has this conscious thought or volition instigated movement A, than A, through the sensation a of its own occurrence, awakens B reflexly; B then excites C through b, and so on till the chain is ended, when the intellect generally takes cognizance of the final result. The intellectual perception at the end is indicated in the diagram by the sensible effect of the movement G being represented at G´, in the ideational centres above the merely sensational line. The sensational impressions, a, b, c, d, e, f, are all supposed to have their seat below the ideational level.

Habits depend on sensations not attended to. We have called a, b, c, d, e, f, by the name of 'sensations.' If sensations, they are sensations to which we are usually inattentive; but that they are more than unconscious nerve-currents seems certain, for they catch our attention if they go wrong. Schneider's account of these sensations deserves to be quoted. In the act of walking, he says, even when our attention is entirely absorbed elsewhere,{142} it is doubtful whether we could preserve equilibrium if no sensation of our body's attitude were there, and doubtful whether we should advance our leg if we had no sensation of its movement as executed, and not even a minimal feeling of impulse to set it down. Knitting appears altogether mechanical, and the knitter keeps up her knitting even while she reads or is engaged in lively talk. But if we ask her how this is possible, she will hardly reply that the knitting goes on of itself. She will rather say that she has a feeling of it, that she feels in her hands that she knits and how she must knit, and that therefore the movements of knitting are called forth and regulated by the sensations associated therewithal, even when the attention is called away...." Again: "When a pupil begins to play on the violin, to keep him from raising his right elbow in playing a book is placed under his right armpit, which he is ordered to hold fast by keeping the upper arm tight against his body. The muscular feelings, and feelings of contact connected with the book, provoke an impulse to press it tight. But often it happens that the beginner, whose attention gets absorbed in the production of the notes, lets drop the book. Later, however, this never happens; the faintest sensations of contact suffice to awaken the impulse to keep it in its place, and the attention may be wholly absorbed by the notes and the fingering with the left hand. The simultaneous combination of movements is thus in the first instance conditioned by the facility with which in us, alongside of intellectual processes, processes of inattentive feeling may still go on."

Ethical and Pedagogical Importance of the Principle of Habit.—"Habit a second nature! Habit is ten times nature," the Duke of Wellington is said to have exclaimed; and the degree to which this is true no one probably can appreciate as well as one who is a veteran soldier himself. The daily drill and the years of discipline end by fashioning a man completely over again, as to most of the possibilities of his conduct.{143}

"There is a story," says Prof. Huxley, "which is credible enough, though it may not be true, of a practical joker who, seeing a discharged veteran carrying home his dinner, suddenly called out, 'Attention!' whereupon the man instantly brought his hands down, and lost his mutton and potatoes in the gutter. The drill had been thorough, and its effects had become embodied in the man's nervous structure."

Riderless cavalry-horses, at many a battle, have been seen to come together and go through their customary evolutions at the sound of the bugle-call. Most domestic beasts seem machines almost pure and simple, undoubtingly, unhesitatingly doing from minute to minute the duties they have been taught, and giving no sign that the possibility of an alternative ever suggests itself to their mind. Men grown old in prison have asked to be readmitted after being once set free. In a railroad accident a menagerie-tiger, whose cage had broken open, is said to have emerged, but presently crept back again, as if too much bewildered by his new responsibilities, so that he was without difficulty secured.

Habit is thus the enormous fly-wheel of society, its most precious conservative agent. It alone is what keeps us all within the bounds of ordinance, and saves the children of fortune from the envious uprisings of the poor. It alone prevents the hardest and most repulsive walks of life from being deserted by those brought up to tread therein. It keeps the fisherman and the deck-hand at sea through the winter; it holds the miner in his darkness, and nails the countryman to his log-cabin and his lonely farm through all the months of snow; it protects us from invasion by the natives of the desert and the frozen zone. It dooms us all to fight out the battle of life upon the lines of our nurture or our early choice, and to make the best of a pursuit that disagrees, because there is no other for which we are fitted, and it is too late to begin again. It keeps different social strata from mixing. Already at the age of twenty-five you{144} see the professional mannerism settling down on the young commercial traveller, on the young doctor, on the young minister, on the young counsellor-at-law. You see the little lines of cleavage running through the character, the tricks of thought, the prejudices, the ways of the 'shop,' in a word, from which the man can by-and-by no more escape than his coat-sleeve can suddenly fall into a new set of folds. On the whole, it is best he should not escape. It is well for the world that in most of us, by the age of thirty, the character has set like plaster, and will never soften again.

If the period between twenty and thirty is the critical one in the formation of intellectual and professional habits, the period below twenty is more important still for the fixing of personal habits, properly so called, such as vocalization and pronunciation, gesture, motion, and address. Hardly ever is a language learned after twenty spoken without a foreign accent; hardly ever can a youth transferred to the society of his betters unlearn the nasality and other vices of speech bred in him by the associations of his growing years. Hardly ever, indeed, no matter how much money there be in his pocket, can he even learn to dress like a gentleman-born. The merchants offer their wares as eagerly to him as to the veriest 'swell,' but he simply cannot buy the right things. An invisible law, as strong as gravitation, keeps him within his orbit, arrayed this year as he was the last; and how his better-clad acquaintances contrive to get the things they wear will be for him a mystery till his dying day.

The great thing, then, in all education, is to make our nervous system our ally instead of our enemy. It is to fund and capitalize our acquisitions, and live at ease upon the interest of the fund. For this we must make automatic and habitual, as early as possible, as many useful actions as we can, and guard against the growing into ways that are likely to be disadvantageous to us, as we should guard against the plague. The more of the details of our daily life we{145} can hand over to the effortless custody of automatism, the more our higher powers of mind will be set free for their own proper work. There is no more miserable human being than one in whom nothing is habitual but indecision, and for whom the lighting of every cigar, the drinking of every cup, the time of rising and going to bed every day, and the beginning of every bit of work, are subjects of express volitional deliberation. Full half the time of such a man goes to the deciding, or regretting, of matters which ought to be so ingrained in him as practically not to exist for his consciousness at all. If there be such daily duties not yet ingrained in any one of my readers, let him begin this very hour to set the matter right.

In Professor Bain's chapter on 'The Moral Habits' there are some admirable practical remarks laid down. Two great maxims emerge from his treatment. The first is that in the acquisition of a new habit, or the leaving off of an old one, we must take care to launch ourselves with as strong and decided an initiative as possible. Accumulate all the possible circumstances which shall re-enforce the right motives; put yourself assiduously in conditions that encourage the new way; make engagements incompatible with the old; take a public pledge, if the case allows; in short, envelop your resolution with every aid you know. This will give your new beginning such a momentum that the temptation to break down will not occur as soon as it otherwise might; and every day during which a breakdown is postponed adds to the chances of its not occurring at all.

The second maxim is: Never suffer an exception to occur till the new habit is securely rooted in your life. Each lapse is like the letting fall of a ball of string which one is carefully winding up; a single slip undoes more than a great many turns will wind again. Continuity of training is the great means of making the nervous system act infallibly right. As Professor Bain says:

"The peculiarity of the moral habits, contradistinguishing{146} them from the intellectual acquisitions, is the presence of two hostile powers, one to be gradually raised into the ascendant over the other. It is necessary, above all things, in such a situation, never to lose a battle. Every gain on the wrong side undoes the effect of many conquests on the right. The essential precaution, therefore, is so to regulate the two opposing powers that the one may have a series of uninterrupted successes, until repetition has fortified it to such a degree as to enable it to cope with the opposition, under any circumstances. This is the theoretically best career of mental progress."

The need of securing success at the outset is imperative. Failure at first is apt to damp the energy of all future attempts, whereas past experiences of success nerve one to future vigor. Goethe says to a man who consulted him about an enterprise but mistrusted his own powers: "Ach! you need only blow on your hands!" And the remark illustrates the effect on Goethe's spirits of his own habitually successful career.

The question of "tapering-off," in abandoning such habits as drink and opium-indulgence comes in here, and is a question about which experts differ within certain limits, and in regard to what may be best for an individual case. In the main, however, all expert opinion would agree that abrupt acquisition of the new habit is the best way, if there be a real possibility of carrying it out. We must be careful not to give the will so stiff a task as to insure its defeat at the very outset; but, provided one can stand it, a sharp period of suffering, and then a free time, is the best thing to aim at, whether in giving up a habit like that of opium, or in simply changing one's hours of rising or of work. It is surprising how soon a desire will die of inanition if it be never fed.

"One must first learn, unmoved, looking neither to the right nor left, to walk firmly on the strait and narrow path, before one can begin 'to make one's self over again.' He who every day makes a fresh resolve is like one who,{147} arriving at the edge of the ditch he is to leap, forever stops and returns for a fresh run. Without unbroken advance there is no such thing as accumulation of the ethical forces possible, and to make this possible, and to exercise us and habituate us in it, is the sovereign blessing of regular work."[31]

A third maxim may be added to the preceding pair: Seize the very first possible opportunity to act on every resolution you make, and on every emotional prompting you may experience in the direction of the habits you aspire to gain. It is not in the moment of their forming, but in the moment of their producing motor effects, that resolves and aspirations communicate the new 'set' to the brain. As the author last quoted remarks:

"The actual presence of the practical opportunity alone furnishes the fulcrum upon which the lever can rest, by means of which the moral will may multiply its strength, and raise itself aloft. He who has no solid ground to press against will never get beyond the stage of empty gesture-making."

No matter how full a reservoir of maxims one may possess, and no matter how good one's sentiments may be, if one have not taken advantage of every concrete opportunity to act, one's character may remain entirely unaffected for the better. With mere good intentions, hell is proverbially paved. And this is an obvious consequence of the principles we have laid down. A 'character,' as J. S. Mill says, 'is a completely fashioned will'; and a will, in the sense in which he means it, is an aggregate of tendencies to act in a firm and prompt and definite way upon all the principal emergencies of life. A tendency to act only becomes effectively ingrained in us in proportion to the uninterrupted frequency with which the actions actually occur, and the brain 'grows' to their use. When a resolve or a fine glow of feeling is allowed to evaporate without{148} bearing practical fruit it is worse than a chance lost; it works so as positively to hinder future resolutions and emotions from taking the normal path of discharge. There is no more contemptible type of human character than that of the nerveless sentimentalist and dreamer, who spends his life in a weltering sea of sensibility and emotion, but who never does a manly concrete deed. Rousseau, inflaming all the mothers of France, by his eloquence, to follow Nature and nurse their babies themselves, while he sends his own children to the foundling hospital, is the classical example of what I mean. But every one of us in his measure, whenever, after glowing for an abstractly formulated Good, he practically ignores some actual case, among the squalid 'other particulars' of which that same Good lurks disguised, treads straight on Rousseau's path. All Goods are disguised by the vulgarity of their concomitants, in this work-a-day world; but woe to him who can only recognize them when he thinks them in their pure and abstract form! The habit of excessive novel-reading and theatre-going will produce true monsters in this line. The weeping of the Russian lady over the fictitious personages in the play, while her coachman is freezing to death on his seat outside, is the sort of thing that everywhere happens on a less glaring scale. Even the habit of excessive indulgence in music, for those who are neither performers themselves nor musically gifted enough to take it in a purely intellectual way, has probably a relaxing effect upon the character. One becomes filled with emotions which habitually pass without prompting to any deed, and so the inertly sentimental condition is kept up. The remedy would be, never to suffer one's self to have an emotion at a concert, without expressing it afterward in some active way. Let the expression be the least thing in the world—speaking genially to one's grandmother, or giving up one's seat in a horse-car, if nothing more heroic offers—but let it not fail to take place.

These latter cases make us aware that it is not simply{149} particular lines of discharge, but also general forms of discharge, that seem to be grooved out by habit in the brain. Just as, if we let our emotions evaporate, they get into a way of evaporating; so there is reason to suppose that if we often flinch from making an effort, before we know it the effort-making capacity will be gone; and that, if we suffer the wandering of our attention, presently it will wander all the time. Attention and effort are, as we shall see later, but two names for the same psychic fact. To what brain-processes they correspond we do not know. The strongest reason for believing that they do depend on brain-processes at all, and are not pure acts of the spirit, is just this fact, that they seem in some degree subject to the law of habit, which is a material law. As a final practical maxim, relative to these habits of the will, we may, then, offer something like this: Keep the faculty of effort alive in you by a little gratuitous exercise every day. That is, be systematically ascetic or heroic in little unnecessary points, do every day or two something for no other reason than that you would rather not do it, so that when the hour of dire need draws nigh, it may find you not unnerved and untrained to stand the test. Asceticism of this sort is like the insurance which a man pays on his house and goods. The tax does him no good at the time, and possibly may never bring him a return. But if the fire does come, his having paid it will be his salvation from ruin. So with the man who has daily inured himself to habits of concentrated attention, energetic volition, and self-denial in unnecessary things. He will stand like a tower when everything rocks around him, and when his softer fellow-mortals are winnowed like chaff in the blast.

The physiological study of mental conditions is thus the most powerful ally of hortatory ethics. The hell to be endured hereafter, of which theology tells, is no worse than the hell we make for ourselves in this world by habitually fashioning our characters in the wrong way. Could the young but realize how soon they will become mere walking{150} bundles of habits, they would give more heed to their conduct while in the plastic state. We are spinning our own fates, good or evil, and never to be undone. Every smallest stroke of virtue or of vice leaves its never so little scar. The drunken Rip Van Winkle, in Jefferson's play, excuses himself for every fresh dereliction by saying, 'I won't count this time!' Well! he may not count it, and a kind Heaven may not count it; but it is being counted none the less. Down among his nerve-cells and fibres the molecules are counting it, registering and storing it up to be used against him when the next temptation comes. Nothing we ever do is, in strict scientific literalness, wiped out. Of course this has its good side as well as its bad one. As we become permanent drunkards by so many separate drinks, so we become saints in the moral, and authorities and experts in the practical and scientific spheres, by so many separate acts and hours of work. Let no youth have any anxiety about the upshot of his education, whatever the line of it may be. If he keep faithfully busy each hour of the working day, he may safely leave the final result to itself. He can with perfect certainty count on waking up some fine morning, to find himself one of the competent ones of his generation, in whatever pursuit he may have singled out. Silently, between all the details of his business, the power of judging in all that class of matter will have built itself up within him as a possession that will never pass away. Young people should know this truth in advance. The ignorance of it has probably engendered more discouragement and faint-heartedness in youths embarking on arduous careers than all other causes put together.{151}

The order of our study must be analytic. We are now prepared to begin the introspective study of the adult consciousness itself. Most books adopt the so-called synthetic method. Starting with 'simple ideas of sensation,' and regarding these as so many atoms, they proceed to build up the higher states of mind out of their 'association,' 'integration,' or 'fusion,' as houses are built by the agglutination of bricks. This has the didactic advantages which the synthetic method usually has. But it commits one beforehand to the very questionable theory that our higher states of consciousness are compounds of units; and instead of starting with what the reader directly knows, namely his total concrete states of mind, it starts with a set of supposed 'simple ideas' with which he has no immediate acquaintance at all, and concerning whose alleged interactions he is much at the mercy of any plausible phrase. On every ground, then, the method of advancing from the simple to the compound exposes us to illusion. All pedants and abstractionists will naturally hate to abandon it. But a student who loves the fulness of human nature will prefer to follow the 'analytic' method, and to begin with the most concrete facts, those with which he has a daily acquaintance in his own inner life. The analytic method will discover in due time the elementary parts, if such exist, without danger of precipitate assumption. The reader will bear in mind that our own chapters on sensation have dealt mainly with the physiological conditions thereof. They were put first as a mere matter of convenience, because incoming currents come first. Psychologically they might better have come last. Pure sensations were{152} described on page 12 as processes which in adult life are well-nigh unknown, and nothing was said which could for a moment lead the reader to suppose that they were the elements of composition of the higher states of mind.

The Fundamental Fact.—The first and foremost concrete fact which every one will affirm to belong to his inner experience is the fact that consciousness of some sort goes on. 'States of mind' succeed each other in him. If we could say in English 'it thinks,' as we say 'it rains' or 'it blows,' we should be stating the fact most simply and with the minimum of assumption. As we cannot, we must simply say that thought goes on.

Four Characters in Consciousness.—How does it go on? We notice immediately four important characters in the process, of which it shall be the duty of the present chapter to treat in a general way:

1) Every 'state' tends to be part of a personal consciousness.

2) Within each personal consciousness states are always changing.

3) Each personal consciousness is sensibly continuous.

4) It is interested in some parts of its object to the exclusion of others, and welcomes or rejects—chooses from among them, in a word—all the while.

In considering these four points successively, we shall have to plunge in medias res as regards our nomenclature and use psychological terms which can only be adequately defined in later chapters of the book. But every one knows what the terms mean in a rough way; and it is only in a rough way that we are now to take them. This chapter is like a painter's first charcoal sketch upon his canvas, in which no niceties appear.

When I say every 'state' or 'thought' is part of a personal consciousness, 'personal consciousness' is one of the terms in question. Its meaning we know so long as no one asks us to define it, but to give an accurate account of it is the most difficult of philosophic tasks. This task we must{153} confront in the next chapter; here a preliminary word will suffice.

In this room—this lecture-room, say—there are a multitude of thoughts, yours and mine, some of which cohere mutually, and some not. They are as little each-for-itself and reciprocally independent as they are all-belonging-together. They are neither: no one of them is separate, but each belongs with certain others and with none beside. My thought belongs with my other thoughts, and your thought with your other thoughts. Whether anywhere in the room there be a mere thought, which is nobody's thought, we have no means of ascertaining, for we have no experience of its like. The only states of consciousness that we naturally deal with are found in personal consciousnesses, minds, selves, concrete particular I's and you's.

Each of these minds keeps its own thoughts to itself. There is no giving or bartering between them. No thought even comes into direct sight of a thought in another personal consciousness than its own. Absolute insulation, irreducible pluralism, is the law. It seems as if the elementary psychic fact were not thought or this thought or that thought, but my thought, every thought being owned. Neither contemporaneity, nor proximity in space, nor similarity of quality and content are able to fuse thoughts together which are sundered by this barrier of belonging to different personal minds. The breaches between such thoughts are the most absolute breaches in nature. Every one will recognize this to be true, so long as the existence of something corresponding to the term 'personal mind' is all that is insisted on, without any particular view of its nature being implied. On these terms the personal self rather than the thought might be treated as the immediate datum in psychology. The universal conscious fact is not 'feelings and thoughts exist,' but 'I think' and 'I feel.' No psychology, at any rate, can question the existence of personal selves. Thoughts connected as we feel them to{154} be connected are what we mean by personal selves. The worst a psychology can do is so to interpret the nature of these selves as to rob them of their worth.

Consciousness is in constant change. I do not mean by this to say that no one state of mind has any duration—even if true, that would be hard to establish. What I wish to lay stress on is this, that no state once gone can recur and be identical with what it was before. Now we are seeing, now hearing; now reasoning, now willing; now recollecting, now expecting; now loving, now hating; and in a hundred other ways we know our minds to be alternately engaged. But all these are complex states, it may be said, produced by combination of simpler ones;—do not the simpler ones follow a different law? Are not the sensations which we get from the same object, for example, always the same? Does not the same piano-key, struck with the same force, make us hear in the same way? Does not the same grass give us the same feeling of green, the same sky the same feeling of blue, and do we not get the same olfactory sensation no matter how many times we put our nose to the same flask of cologne? It seems a piece of metaphysical sophistry to suggest that we do not; and yet a close attention to the matter shows that there is no proof that an incoming current ever gives us just the same bodily sensation twice.

What is got twice is the same OBJECT. We hear the same note over and over again; we see the same quality of green, or smell the same objective perfume, or experience the same species of pain. The realities, concrete and abstract, physical and ideal, whose permanent existence we believe in, seem to be constantly coming up again before our thought, and lead us, in our carelessness, to suppose that our 'ideas' of them are the same ideas. When we come, some time later, to the chapter on Perception, we shall see how inveterate is our habit of simply using our sensible impressions as stepping-stones to pass over to the recognition of the realities whose presence they reveal. The grass{155} out of the window now looks to me of the same green in the sun as in the shade, and yet a painter would have to paint one part of it dark brown, another part bright yellow, to give its real sensational effect. We take no heed, as a rule, of the different way in which the same things look and sound and smell at different distances and under different circumstances. The sameness of the things is what we are concerned to ascertain; and any sensations that assure us of that will probably be considered in a rough way to be the same with each other. This is what makes off-hand testimony about the subjective identity of different sensations well-nigh worthless as a proof of the fact. The entire history of what is called Sensation is a commentary on our inability to tell whether two sensible qualities received apart are exactly alike. What appeals to our attention far more than the absolute quality of an impression is its ratio to whatever other impressions we may have at the same time. When everything is dark a somewhat less dark sensation makes us see an object white. Helmholtz calculates that the white marble painted in a picture representing an architectural view by moonlight is, when seen by daylight, from ten to twenty thousand times brighter than the real moonlit marble would be.

Such a difference as this could never have been sensibly learned; it had to be inferred from a series of indirect considerations. These make us believe that our sensibility is altering all the time, so that the same object cannot easily give us the same sensation over again. We feel things differently accordingly as we are sleepy or awake, hungry or full, fresh or tired; differently at night and in the morning, differently in summer and in winter; and above all, differently in childhood, manhood, and old age. And yet we never doubt that our feelings reveal the same world, with the same sensible qualities and the same sensible things occupying it. The difference of the sensibility is shown best by the difference of our emotion about the things from one age to another, or when we are in different{156} organic moods. What was bright and exciting becomes weary, flat, and unprofitable. The bird's song is tedious, the breeze is mournful, the sky is sad.

To these indirect presumptions that our sensations, following the mutations of our capacity for feeling, are always undergoing an essential change, must be added another presumption, based on what must happen in the brain. Every sensation corresponds to some cerebral action. For an identical sensation to recur it would have to occur the second time in an unmodified brain. But as this, strictly speaking, is a physiological impossibility, so is an unmodified feeling an impossibility; for to every brain-modification, however small, we suppose that there must correspond a change of equal amount in the consciousness which the brain subserves.

But if the assumption of 'simple sensations' recurring in immutable shape is so easily shown to be baseless, how much more baseless is the assumption of immutability in the larger masses of our thought!

For there it is obvious and palpable that our state of mind is never precisely the same. Every thought we have of a given fact is, strictly speaking, unique, and only bears a resemblance of kind with our other thoughts of the same fact. When the identical fact recurs, we must think of it in a fresh manner, see it under a somewhat different angle, apprehend it in different relations from those in which it last appeared. And the thought by which we cognize it is the thought of it-in-those-relations, a thought suffused with the consciousness of all that dim context. Often we are ourselves struck at the strange differences in our successive views of the same thing. We wonder how we ever could have opined as we did last month about a certain matter. We have outgrown the possibility of that state of mind, we know not how. From one year to another we see things in new lights. What was unreal has grown real, and what was exciting is insipid. The friends we used to care the world for are shrunken to shadows;{157} the women once so divine, the stars, the woods, and the waters, how now so dull and common!—the young girls that brought an aura of infinity, at present hardly distinguishable existences; the pictures so empty; and as for the books, what was there to find so mysteriously significant in Goethe, or in John Mill so full of weight? Instead of all this, more zestful than ever is the work; and fuller and deeper the import of common duties and of common goods.

I am sure that this concrete and total manner of regarding the mind's changes is the only true manner, difficult as it may be to carry it out in detail. If anything seems obscure about it, it will grow clearer as we advance. Meanwhile, if it be true, it is certainly also true that no two 'ideas' are ever exactly the same, which is the proposition we started to prove. The proposition is more important theoretically than it at first sight seems. For it makes it already impossible for us to follow obediently in the footprints of either the Lockian or the Herbartian school, schools which have had almost unlimited influence in Germany and among ourselves. No doubt it is often convenient to formulate the mental facts in an atomistic sort of way, and to treat the higher states of consciousness as if they were all built out of unchanging simple ideas which 'pass and turn again.' It is convenient often to treat curves as if they were composed of small straight lines, and electricity and nerve-force as if they were fluids. But in the one case as in the other we must never forget that we are talking symbolically, and that there is nothing in nature to answer to our words. A permanently existing 'Idea' which makes its appearance before the footlights of consciousness at periodical intervals is as mythological an entity as the Jack of Spades.

Within each personal consciousness, thought is sensibly continuous. I can only define 'continuous' as that which is without breach, crack, or division. The only breaches that can well be conceived to occur within the limits of a{158} single mind would either be interruptions, time-gaps during which the consciousness went out; or they would be breaks in the content of the thought, so abrupt that what followed had no connection whatever with what went before. The proposition that consciousness feels continuous, means two things:

a. That even where there is a time-gap the consciousness after it feels as if it belonged together with the consciousness before it, as another part of the same self;

b. That the changes from one moment to another in the quality of the consciousness are never absolutely abrupt.

The case of the time-gaps, as the simplest, shall be taken first.

a. When Paul and Peter wake up in the same bed, and recognize that they have been asleep, each one of them mentally reaches back and makes connection with but one of the two streams of thought which were broken by the sleeping hours. As the current of an electrode buried in the ground unerringly finds its way to its own similarly buried mate, across no matter how much intervening earth; so Peter's present instantly finds out Peter's past, and never by mistake knits itself on to that of Paul. Paul's thought in turn is as little liable to go astray. The past thought of Peter is appropriated by the present Peter alone. He may have a knowledge, and a correct one too, of what Paul's last drowsy states of mind were as he sank into sleep, but it is an entirely different sort of knowledge from that which he has of his own last states. He remembers his own states, whilst he only conceives Paul's. Remembrance is like direct feeling; its object is suffused with a warmth and intimacy to which no object of mere conception ever attains. This quality of warmth and intimacy and immediacy is what Peter's present thought also possesses for itself. So sure as this present is me, is mine, it says, so sure is anything else that comes with the same warmth and intimacy and immediacy, me and mine. What the qualities called warmth and intimacy may in{159} themselves be will have to be matter for future consideration. But whatever past states appear with those qualities must be admitted to receive the greeting of the present mental state, to be owned by it, and accepted as belonging together with it in a common self. This community of self is what the time-gap cannot break in twain, and is why a present thought, although not ignorant of the time-gap, can still regard itself as continuous with certain chosen portions of the past.

Consciousness, then, does not appear to itself chopped up in bits. Such words as 'chain' or 'train' do not describe it fitly as it presents itself in the first instance. It is nothing jointed; it flows. A 'river' or a 'stream' are the metaphors by which it is most naturally described. In talking of it hereafter, let us call it the stream of thought, of consciousness, or of subjective life.

b. But now there appears, even within the limits of the same self, and between thoughts all of which alike have this same sense of belonging together, a kind of jointing and separateness among the parts, of which this statement seems to take no account. I refer to the breaks that are produced by sudden contrasts in the quality of the successive segments of the stream of thought. If the words 'chain' and 'train' had no natural fitness in them, how came such words to be used at all? Does not a loud explosion rend the consciousness upon which it abruptly breaks, in twain? No; for even into our awareness of the thunder the awareness of the previous silence creeps and continues; for what we hear when the thunder crashes is not thunder pure, but thunder-breaking-upon-silence-and-contrasting-with-it. Our feeling of the same objective thunder, coming in this way, is quite different from what it would be were the thunder a continuation of previous thunder. The thunder itself we believe to abolish and exclude the silence; but the feeling of the thunder is also a feeling of the silence as just gone; and it would be difficult to find in the actual concrete consciousness of man a{160} feeling so limited to the present as not to have an inkling of anything that went before.

'Substantive' and 'Transitive' States of Mind.—When we take a general view of the wonderful stream of our consciousness, what strikes us first is the different pace of its parts. Like a bird's life, it seems to be an alternation of flights and perchings. The rhythm of language expresses this, where every thought is expressed in a sentence, and every sentence closed by a period. The resting-places are usually occupied by sensorial imaginations of some sort, whose peculiarity is that they can be held before the mind for an indefinite time, and contemplated without changing; the places of flight are filled with thoughts of relations, static or dynamic, that for the most part obtain between the matters contemplated in the periods of comparative rest.

Let us call the resting-places the 'substantive parts,' and the places of flight the 'transitive parts,' of the stream of thought. It then appears that our thinking tends at all times towards some other substantive part than the one from which it has just been dislodged. And we may say that the main use of the transitive parts is to lead us from one substantive conclusion to another.

Now it is very difficult, introspectively, to see the transitive parts for what they really are. If they are but flights to a conclusion, stopping them to look at them before the conclusion is reached is really annihilating them. Whilst if we wait till the conclusion be reached, it so exceeds them in vigor and stability that it quite eclipses and swallows them up in its glare. Let anyone try to cut a thought across in the middle and get a look at its section, and he will see how difficult the introspective observation of the transitive tracts is. The rush of the thought is so headlong that it almost always brings us up at the conclusion before we can arrest it. Or if our purpose is nimble enough and we do arrest it, it ceases forthwith to be itself. As a snowflake crystal caught in the warm hand{161} is no longer a crystal but a drop, so, instead of catching the feeling of relation moving to its term, we find we have caught some substantive thing, usually the last word we were pronouncing, statically taken, and with its function, tendency, and particular meaning in the sentence quite evaporated. The attempt at introspective analysis in these cases is in fact like seizing a spinning top to catch its motion, or trying to turn up the gas quickly enough to see how the darkness looks. And the challenge to produce these transitive states of consciousness, which is sure to be thrown by doubting psychologists at anyone who contends for their existence, is as unfair as Zeno's treatment of the advocates of motion, when, asking them to point out in what place an arrow is when it moves, he argues the falsity of their thesis from their inability to make to so preposterous a question an immediate reply.

The results of this introspective difficulty are baleful. If to hold fast and observe the transitive parts of thought's stream be so hard, then the great blunder to which all schools are liable must be the failure to register them, and the undue emphasizing of the more substantive parts of the stream. Now the blunder has historically worked in two ways. One set of thinkers have been led by it to Sensationalism. Unable to lay their hands on any substantive feelings corresponding to the innumerable relations and forms of connection between the sensible things of the world, finding no named mental states mirroring such relations, they have for the most part denied that any such states exist; and many of them, like Hume, have gone on to deny the reality of most relations out of the mind as well as in it. Simple substantive 'ideas,' sensations and their copies, juxtaposed like dominoes in a game, but really separate, everything else verbal illusion,—such is the upshot of this view. The Intellectualists, on the other hand, unable to give up the reality of relations extra mentem, but equally unable to point to any distinct substantive feelings in which they were known, have made the same admission{162} that such feelings do not exist. But they have drawn an opposite conclusion. The relations must be known, they say, in something that is no feeling, no mental 'state,' continuous and consubstantial with the subjective tissue out of which sensations and other substantive conditions of consciousness are made. They must be known by something that lies on an entirely different plane, by an actus purus of Thought, Intellect, or Reason, all written with capitals and considered to mean something unutterably superior to any passing perishing fact of sensibility whatever.

But from our point of view both Intellectualists and Sensationalists are wrong. If there be such things as feelings at all, then so surely as relations between objects exist in rerum naturâ, so surely, and more surely, do feelings exist to which these relations are known. There is not a conjunction or a preposition, and hardly an adverbial phrase, syntactic form, or inflection of voice, in human speech, that does not express some shading or other of relation which we at some moment actually feel to exist between the larger objects of our thought. If we speak objectively, it is the real relations that appear revealed; if we speak subjectively, it is the stream of consciousness that matches each of them by an inward coloring of its own. In either case the relations are numberless, and no existing language is capable of doing justice to all their shades.

We ought to say a feeling of and, a feeling of if, a feeling of but, and a feeling of by, quite as readily as we say a feeling of blue or a feeling of cold. Yet we do not: so inveterate has our habit become of recognizing the existence of the substantive parts alone, that language almost refuses to lend itself to any other use. Consider once again the analogy of the brain. We believe the brain to be an organ whose internal equilibrium is always in a state of change—the change affecting every part. The pulses of change are doubtless more violent in one place than in{163} another, their rhythm more rapid at this time than at that. As in a kaleidoscope revolving at a uniform rate, although the figures are always rearranging themselves, there are instants during which the transformation seems minute and interstitial and almost absent, followed by others when it shoots with magical rapidity, relatively stable forms thus alternating with forms we should not distinguish if seen again; so in the brain the perpetual rearrangement must result in some forms of tension lingering relatively long, whilst others simply come and pass. But if consciousness corresponds to the fact of rearrangement itself, why, if the rearrangement stop not, should the consciousness ever cease? And if a lingering rearrangement brings with it one kind of consciousness, why should not a swift rearrangement bring another kind of consciousness as peculiar as the rearrangement itself?

The object before the mind always has a 'Fringe.' There are other unnamed modifications of consciousness just as important as the transitive states, and just as cognitive as they. Examples will show what I mean.

Suppose three successive persons say to us: 'Wait!' 'Hark!' 'Look!' Our consciousness is thrown into three quite different attitudes of expectancy, although no definite object is before it in any one of the three cases. Probably no one will deny here the existence of a real conscious affection, a sense of the direction from which an impression is about to come, although no positive impression is yet there. Meanwhile we have no names for the psychoses in question but the names hark, look, and wait.

Suppose we try to recall a forgotten name. The state of our consciousness is peculiar. There is a gap therein; but no mere gap. It is a gap that is intensely active. A sort of wraith of the name is in it, beckoning us in a given direction, making us at moments tingle with the sense of our closeness, and then letting us sink back without the longed-for term. If wrong names are proposed to us, this singularly definite gap acts immediately so as to negate{164} them. They do not fit into its mould. And the gap of one word does not feel like the gap of another, all empty of content as both might seem necessarily to be when described as gaps. When I vainly try to recall the name of Spalding, my consciousness is far removed from what it is when I vainly try to recall the name of Bowles. There are innumerable consciousnesses of want, no one of which taken in itself has a name, but all different from each other. Such a feeling of want is toto cœlo other than a want of feeling: it is an intense feeling. The rhythm of a lost word may be there without a sound to clothe it; or the evanescent sense of something which is the initial vowel or consonant may mock us fitfully, without growing more distinct. Every one must know the tantalizing effect of the blank rhythm of some forgotten verse, restlessly dancing in one's mind, striving to be filled out with words.

What is that first instantaneous glimpse of some one's meaning which we have, when in vulgar phrase we say we 'twig' it? Surely an altogether specific affection of our mind. And has the reader never asked himself what kind of a mental fact is his intention of saying a thing before he has said it? It is an entirely definite intention, distinct from all other intentions, an absolutely distinct state of consciousness, therefore; and yet how much of it consists of definite sensorial images, either of words or of things? Hardly anything! Linger, and the words and things come into the mind; the anticipatory intention, the divination is there no more. But as the words that replace it arrive, it welcomes them successively and calls them right if they agree with it, it rejects them and calls them wrong if they do not. The intention to-say-so-and-so is the only name it can receive. One may admit that a good third of our psychic life consists in these rapid premonitory perspective views of schemes of thought not yet articulate. How comes it about that a man reading something aloud for the first time is able immediately to{165} emphasize all his words aright, unless from the very first he have a sense of at least the form of the sentence yet to come, which sense is fused with his consciousness of the present word, and modifies its emphasis in his mind so as to make him give it the proper accent as he utters it? Emphasis of this kind almost altogether depends on grammatical construction. If we read 'no more,' we expect presently a 'than'; if we read 'however,' it is a 'yet,' a 'still,' or a 'nevertheless,' that we expect. And this foreboding of the coming verbal and grammatical scheme is so practically accurate that a reader incapable of understanding four ideas of the book he is reading aloud can nevertheless read it with the most delicately modulated expression of intelligence.

It is, the reader will see, the reinstatement of the vague and inarticulate to its proper place in our mental life which I am so anxious to press on the attention. Mr. Galton and Prof. Huxley have, as we shall see in the chapter on Imagination, made one step in advance in exploding the ridiculous theory of Hume and Berkeley that we can have no images but of perfectly definite things. Another is made if we overthrow the equally ridiculous notion that, whilst simple objective qualities are revealed to our knowledge in 'states of consciousness,' relations are not. But these reforms are not half sweeping and radical enough. What must be admitted is that the definite images of traditional psychology form but the very smallest part of our minds as they actually live. The traditional psychology talks like one who should say a river consists of nothing but pailsful, spoonsful, quartpotsful, barrelsful, and other moulded forms of water. Even were the pails and the pots all actually standing in the stream, still between them the free water would continue to flow. It is just this free water of consciousness that psychologists resolutely overlook. Every definite image in the mind is steeped and dyed in the free water that flows round it. With it goes the sense of its relations, near and remote, the dying echo{166} of whence it came to us, the dawning sense of whither it is to lead. The significance, the value, of the image is all in this halo or penumbra that surrounds and escorts it,—or rather that is fused into one with it and has become bone of its bone and flesh of its flesh; leaving it, it is true, an image of the same thing it was before, but making it an image of that thing newly taken and freshly understood.

Let us call the consciousness of this halo of relations around the image by the name of 'psychic overtone' or 'fringe.'

Cerebral Conditions of the 'Fringe.'—Nothing is easier than to symbolize these facts in terms of brain-action. Just as the echo of the whence, the sense of the starting point of our thought, is probably due to the dying excitement of processes but a moment since vividly aroused; so the sense of the whither, the foretaste of the terminus, must be due to the waxing excitement of tracts or processes whose psychical correlative will a moment hence be the vividly present feature of our thought. Represented by a curve, the neurosis underlying consciousness must at any moment be like this:

Let the horizontal in Fig. 52 be the line of time, and let the three curves beginning at a, b, and c respectively stand for the neural processes correlated with the thoughts of those three letters. Each process occupies a certain time during which its intensity waxes, culminates, and wanes. The process for a has not yet died out, the process{167} for c has already begun, when that for b is culminating. At the time-instant represented by the vertical line all three processes are present, in the intensities shown by the curve. Those before c's apex were more intense a moment ago; those after it will be more intense a moment hence. If I recite a, b, c, then, at the moment of uttering b, neither a nor c is out of my consciousness altogether, but both, after their respective fashions, 'mix their dim lights' with the stronger b, because their processes are both awake in some degree.

It is just like 'overtones' in music: they are not separately heard by the ear; they blend with the fundamental note, and suffuse it, and alter it; and even so do the waxing and waning brain-processes at every moment blend with and suffuse and alter the psychic effect of the processes which are at their culminating point.

The 'Topic' of the Thought.—If we then consider the cognitive function of different states of mind, we may feel assured that the difference between those that are mere 'acquaintance' and those that are 'knowledges-about' is reducible almost entirely to the absence or presence of psychic fringes or overtones. Knowledge about a thing is knowledge of its relations. Acquaintance with it is limitation to the bare impression which it makes. Of most of its relations we are only aware in the penumbral nascent way of a 'fringe' of unarticulated affinities about it. And, before passing to the next topic in order, I must say a little of this sense of affinity, as itself one of the most interesting features of the subjective stream.

Thought may be equally rational in any sort of terms. In all our voluntary thinking there is some TOPIC or SUBJECT about which all the members of the thought revolve. Relation to this topic or interest is constantly felt in the fringe, and particularly the relation of harmony and discord, of furtherance or hindrance of the topic. Any thought the quality of whose fringe lets us feel ourselves 'all right,' may be considered a thought that furthers the{168} topic. Provided we only feel its object to have a place in the scheme of relations in which the topic also lies, that is sufficient to make of it a relevant and appropriate portion of our train of ideas.

Now we may think about our topic mainly in words, or we may think about it mainly in visual or other images, but this need make no difference as regards the furtherance of our knowledge of the topic. If we only feel in the terms, whatever they be, a fringe of affinity with each other and with the topic, and if we are conscious of approaching a conclusion, we feel that our thought is rational and right. The words in every language have contracted by long association fringes of mutual repugnance or affinity with each other and with the conclusion, which run exactly parallel with like fringes in the visual, tactile, and other ideas. The most important element of these fringes is, I repeat, the mere feeling of harmony or discord, of a right or wrong direction in the thought.

If we know English and French and begin a sentence in French, all the later words that come are French; we hardly ever drop into English. And this affinity of the French words for each other is not something merely operating mechanically as a brain-law, it is something we feel at the time. Our understanding of a French sentence heard never falls to so low an ebb that we are not aware that the words linguistically belong together. Our attention can hardly so wander that if an English word be suddenly introduced we shall not start at the change. Such a vague sense as this of the words belonging together is the very minimum of fringe that can accompany them, if 'thought' at all. Usually the vague perception that all the words we hear belong to the same language and to the same special vocabulary in that language, and that the grammatical sequence is familiar, is practically equivalent to an admission that what we hear is sense. But if an unusual foreign word be introduced, if the grammar trip, or if a term from an incongruous vocabulary suddenly appear,{169} such as 'rat-trap' or 'plumber's bill' in a philosophical discourse, the sentence detonates as it were, we receive a shock from the incongruity, and the drowsy assent is gone. The feeling of rationality in these cases seems rather a negative than a positive thing, being the mere absence of shock, or sense of discord, between the terms of thought.

Conversely, if words do belong to the same vocabulary, and if the grammatical structure is correct, sentences with absolutely no meaning may be uttered in good faith and pass unchallenged. Discourses at prayer-meetings, re-shuffling the same collection of cant phrases, and the whole genus of penny-a-line-isms and newspaper-reporter's flourishes give illustrations of this. "The birds filled the tree-tops with their morning song, making the air moist, cool, and pleasant," is a sentence I remember reading once in a report of some athletic exercises in Jerome Park. It was probably written unconsciously by the hurried reporter, and read uncritically by many readers.

We see, then, that it makes little or no difference in what sort of mind-stuff, in what quality of imagery, our thinking goes on. The only images intrinsically important are the halting-places, the substantive conclusions, provisional or final, of the thought. Throughout all the rest of the stream, the feelings of relation are everything, and the terms related almost naught. These feelings of relation, these psychic overtones, halos, suffusions, or fringes about the terms, may be the same in very different systems of imagery. A diagram may help to accentuate this indifference of the mental means where the end is the same. Let A be some experience from which a number of thinkers start. Let Z be the practical conclusion rationally inferrible from it. One gets to this conclusion by one line, another{170} by another; one follows a course of English, another of German, verbal imagery. With one, visual images predominate; with another, tactile. Some trains are tinged with emotions, others not; some are very abridged, synthetic and rapid; others, hesitating and broken into many steps. But when the penultimate terms of all the trains, however differing inter se, finally shoot into the same conclusion, we say, and rightly say, that all the thinkers have had substantially the same thought. It would probably astound each of them beyond measure to be let into his neighbor's mind and to find how different the scenery there was from that in his own.

The last peculiarity to which attention is to be drawn in this first rough description of thought's stream is that—

Consciousness is always interested more in one part of its object than in another, and welcomes and rejects, or chooses, all the while it thinks.

The phenomena of selective attention and of deliberative will are of course patent examples of this choosing activity. But few of us are aware how incessantly it is at work in operations not ordinarily called by these names. Accentuation and Emphasis are present in every perception we have. We find it quite impossible to disperse our attention impartially over a number of impressions. A monotonous succession of sonorous strokes is broken up into rhythms, now of one sort, now of another, by the different accent which we place on different strokes. The simplest of these rhythms is the double one, tick-tóck, tick-tóck, tick-tóck. Dots dispersed on a surface are perceived in rows and groups. Lines separate into diverse figures. The ubiquity of the distinctions, this and that, here and there, now and then, in our minds is the result of our laying the same selective emphasis on parts of place and time.

But we do far more than emphasize things, and unite some, and keep others apart. We actually ignore most of the things before us. Let me briefly show how this goes on.{171}

To begin at the bottom, what are our very senses themselves, as we saw on pp. 10-12, but organs of selection? Out of the infinite chaos of movements, of which physics teaches us that the outer world consists, each sense-organ picks out those which fall within certain limits of velocity. To these it responds, but ignores the rest as completely as if they did not exist. Out of what is in itself an undistinguishable, swarming continuum, devoid of distinction or emphasis, our senses make for us, by attending to this motion and ignoring that, a world full of contrasts, of sharp accents, of abrupt changes, of picturesque light and shade.

If the sensations we receive from a given organ have their causes thus picked out for us by the conformation of the organ's termination, Attention, on the other hand, out of all the sensations yielded, picks out certain ones as worthy of its notice and suppresses all the rest. We notice only those sensations which are signs to us of things which happen practically or æsthetically to interest us, to which we therefore give substantive names, and which we exalt to this exclusive status of independence and dignity. But in itself, apart from my interest, a particular dust-wreath on a windy day is just as much of an individual thing, and just as much or as little deserves an individual name, as my own body does.

And then, among the sensations we get from each separate thing, what happens? The mind selects again. It chooses certain of the sensations to represent the thing most truly, and considers the rest as its appearances, modified by the conditions of the moment. Thus my table-top is named square, after but one of an infinite number of retinal sensations which it yields, the rest of them being sensations of two acute and two obtuse angles; but I call the latter perspective views, and the four right angles the true form of the table, and erect the attribute squareness into the table's essence, for æsthetic reasons of my own. In like manner, the real form of the circle is deemed to be{172} the sensation it gives when the line of vision is perpendicular to its centre—all its other sensations are signs of this sensation. The real sound of the cannon is the sensation it makes when the ear is close by. The real color of the brick is the sensation it gives when the eye looks squarely at it from a near point, out of the sunshine and yet not in the gloom; under other circumstances it gives us other color-sensations which are but signs of this—we then see it looks pinker or bluer than it really is. The reader knows no object which he does not represent to himself by preference as in some typical attitude, of some normal size, at some characteristic distance, of some standard tint, etc., etc. But all these essential characteristics, which together form for us the genuine objectivity of the thing and are contrasted with what we call the subjective sensations it may yield us at a given moment, are mere sensations like the latter. The mind chooses to suit itself, and decides what particular sensation shall be held more real and valid than all the rest.

Next, in a world of objects thus individualized by our mind's selective industry, what is called our 'experience' is almost entirely determined by our habits of attention. A thing may be present to a man a hundred times, but if he persistently fails to notice it, it cannot be said to enter into his experience. We are all seeing flies, moths, and beetles by the thousand, but to whom, save an entomologist, do they say anything distinct? On the other hand, a thing met only once in a lifetime may leave an indelible experience in the memory. Let four men make a tour in Europe. One will bring home only picturesque impressions—costumes and colors, parks and views and works of architecture, pictures and statues. To another all this will be non-existent; and distances and prices, populations and drainage-arrangements, door-and window-fastenings, and other useful statistics will take their place. A third will give a rich account of the theatres, restaurants, and public halls, and naught beside; whilst the fourth will perhaps have been so{173} wrapped in his own subjective broodings as to be able to tell little more than a few names of places through which he passed. Each has selected, out of the same mass of presented objects, those which suited his private interest and has made his experience thereby.

If now, leaving the empirical combination of objects, we ask how the mind proceeds rationally to connect them, we find selection again to be omnipotent. In a future chapter we shall see that all Reasoning depends on the ability of the mind to break up the totality of the phenomenon reasoned about, into parts, and to pick out from among these the particular one which, in the given emergency, may lead to the proper conclusion. The man of genius is he who will always stick in his bill at the right point, and bring it out with the right element—'reason' if the emergency be theoretical, 'means' if it be practical—transfixed upon it.

If now we pass to the æsthetic department, our law is still more obvious. The artist notoriously selects his items, rejecting all tones, colors, shapes, which do not harmonize with each other and with the main purpose of his work. That unity, harmony, 'convergence of characters,' as M. Taine calls it, which gives to works of art their superiority over works of nature, is wholly due to elimination. Any natural subject will do, if the artist has wit enough to pounce upon some one feature of it as characteristic, and suppress all merely accidental items which do not harmonize with this.

Ascending still higher, we reach the plane of Ethics, where choice reigns notoriously supreme. An act has no ethical quality whatever unless it be chosen out of several all equally possible. To sustain the arguments for the good course and keep them ever before us, to stifle our longing for more flowery ways, to keep the foot unflinchingly on the arduous path, these are characteristic ethical energies. But more than these; for these but deal with the means of compassing interests already felt by the man{174} to be supreme. The ethical energy par excellence has to go farther and choose which interest out of several, equally coercive, shall become supreme. The issue here is of the utmost pregnancy, for it decides a man's entire career. When he debates, Shall I commit this crime? choose that profession? accept that office, or marry this fortune?—his choice really lies between one of several equally possible future Characters. What he shall become is fixed by the conduct of this moment. Schopenhauer, who enforces his determinism by the argument that with a given fixed character only one reaction is possible under given circumstances, forgets that, in these critical ethical moments, what consciously seems to be in question is the complexion of the character itself. The problem with the man is less what act he shall now resolve to do than what being he shall now choose to become.

Taking human experience in a general way, the choosings of different men are to a great extent the same. The race as a whole largely agrees as to what it shall notice and name; and among the noticed parts we select in much the same way for accentuation and preference, or subordination and dislike. There is, however, one entirely extraordinary case in which no two men ever are known to choose alike. One great splitting of the whole universe into two halves is made by each of us; and for each of us almost all of the interest attaches to one of the halves; but we all draw the line of division between them in a different place. When I say that we all call the two halves by the same names, and that those names are 'me' and 'not-me' respectively, it will at once be seen what I mean. The altogether unique kind of interest which each human mind feels in those parts of creation which it can call me or mine may be a moral riddle, but it is a fundamental psychological fact. No mind can take the same interest in his neighbor's me as in his own. The neighbor's me falls together with all the rest of things in one foreign mass against which his own me stands out in startling relief.{175} Even the trodden worm, as Lotze somewhere says, contrasts his own suffering self with the whole remaining universe, though he have no clear conception either of himself or of what the universe may be. He is for me a mere part of the world; for him it is I who am the mere part. Each of us dichotomizes the Kosmos in a different place.

Descending now to finer work than this first general sketch, let us in the next chapter try to trace the psychology of this fact of self-consciousness to which we have thus once more been led.{176}

The Me and the I.—Whatever I may be thinking of, I am always at the same time more or less aware of myself, of my personal existence. At the same time it is I who am aware; so that the total self of me, being as it were duplex, partly known and partly knower, partly object and partly subject, must have two aspects discriminated in it, of which for shortness we may call one the Me and the other the I. I call these 'discriminated aspects,' and not separate things, because the identity of I with me, even in the very act of their discrimination, is perhaps the most ineradicable dictum of common-sense, and must not be undermined by our terminology here at the outset, whatever we may come to think of its validity at our inquiry's end.

I shall therefore treat successively of A) the self as known, or the me, the 'empirical ego' as it is sometimes called; and of B) the self as knower, or the I, the 'pure ego' of certain authors.

The Empirical Self or Me.—Between what a man calls me and what he simply calls mine the line is difficult to draw. We feel and act about certain things that are ours very much as we feel and act about ourselves. Our fame, our children, the work of our hands, may be as dear to us as our bodies are, and arouse the same feelings and the same acts of reprisal if attacked. And our bodies themselves, are they simply ours, or are they us? Certainly{177} men have been ready to disown their very bodies and to regard them as mere vestures, or even as prisons of clay from which they should some day be glad to escape.

We see then that we are dealing with a fluctuating material; the same object being sometimes treated as a part of me, at other times as simply mine, and then again as if I had nothing to do with it at all. In its widest possible sense, however, a man's Me is the sum total of all that he CAN call his, not only his body and his psychic powers, but his clothes and his house, his wife and children, his ancestors and friends, his reputation and works, his lands and horses, and yacht and bank-account. All these things give him the same emotions. If they wax and prosper, he feels triumphant; if they dwindle and die away, he feels cast down,—not necessarily in the same degree for each thing, but in much the same way for all. Understanding the Me in this widest sense, we may begin by dividing the history of it into three parts, relating respectively to—

a. Its constituents;

b. The feelings and emotions they arouse,—self-appreciation;

c. The act to which they prompt,—self-seeking and self-preservation.

a. The constituents of the Me may be divided into two classes, those which make up respectively—

The Material Me.—The body is the innermost part of the material me in each of us; and certain parts of the body seem more intimately ours than the rest. The clothes come next. The old saying that the human person is composed of three parts—soul, body and clothes—is more than a joke. We so appropriate our clothes and identify ourselves{178} with them that there are few of us who, if asked to choose between having a beautiful body clad in raiment perpetually shabby and unclean, and having an ugly and blemished form always spotlessly attired, would not hesitate a moment before making a decisive reply. Next, our immediate family is a part of ourselves. Our father and mother, our wife and babes, are bone of our bone and flesh of our flesh. When they die, a part of our very selves is gone. If they do anything wrong, it is our shame. If they are insulted, our anger flashes forth as readily as if we stood in their place. Our home comes next. Its scenes are part of our life; its aspects awaken the tenderest feelings of affection; and we do not easily forgive the stranger who, in visiting it, finds fault with its arrangements or treats it with contempt. All these different things are the objects of instinctive preferences coupled with the most important practical interests of life. We all have a blind impulse to watch over our body, to deck it with clothing of an ornamental sort, to cherish parents, wife, and babes, and to find for ourselves a house of our own which we may live in and 'improve.'

An equally instinctive impulse drives us to collect property; and the collections thus made become, with different degrees of intimacy, parts of our empirical selves. The parts of our wealth most intimately ours are those which are saturated with our labor. There are few men who would not feel personally annihilated if a life-long construction of their hands or brains—say an entomological collection or an extensive work in manuscript—were suddenly swept away. The miser feels similarly towards his gold; and although it is true that a part of our depression at the loss of possessions is due to our feeling that we must now go without certain goods that we expected the possessions to bring in their train, yet in every case there remains, over and above this, a sense of the shrinkage of our personality, a partial conversion of ourselves to nothingness, which is a psychological phenomenon by itself. We{179} are all at once assimilated to the tramps and poor devils whom we so despise, and at the same time removed farther than ever away from the happy sons of earth who lord it over land and sea and men in the full-blown lustihood that wealth and power can give, and before whom, stiffen ourselves as we will by appealing to anti-snobbish first principles, we cannot escape an emotion, open or sneaking, of respect and dread.

The Social Me.—A man's social me is the recognition which he gets from his mates. We are not only gregarious animals, liking to be in sight of our fellows, but we have an innate propensity to get ourselves noticed, and noticed favorably, by our kind. No more fiendish punishment could be devised, were such a thing physically possible, than that one should be turned loose in society and remain absolutely unnoticed by all the members thereof. If no one turned round when we entered, answered when we spoke, or minded what we did, but if every person we met 'cut us dead,' and acted as if we were non-existing things, a kind of rage and impotent despair would ere long well up in us, from which the cruellest bodily tortures would be a relief; for these would make us feel that, however bad might be our plight, we had not sunk to such a depth as to be unworthy of attention at all.

Properly speaking, a man has as many social selves as there are individuals who recognize him and carry an image of him in their mind. To wound any one of these his images is to wound him. But as the individuals who carry the images fall naturally into classes, we may practically say that he has as many different social selves as there are distinct groups of persons about whose opinion he cares. He generally shows a different side of himself to each of these different groups. Many a youth who is demure enough before his parents and teachers, swears and swaggers like a pirate among his 'tough' young friends. We do not show ourselves to our children as to our club-companions, to our customers as to the laborers we employ,{180} to our own masters and employers as to our intimate friends. From this there results what practically is a division of the man into several selves; and this may be a discordant splitting, as where one is afraid to let one set of his acquaintances know him as he is elsewhere; or it may be a perfectly harmonious division of labor, as where one tender to his children is stern to the soldiers or prisoners under his command.

The most peculiar social self which one is apt to have is in the mind of the person one is in love with. The good or bad fortunes of this self cause the most intense elation and dejection—unreasonable enough as measured by every other standard than that of the organic feeling of the individual. To his own consciousness he is not, so long as this particular social self fails to get recognition, and when it is recognized his contentment passes all bounds.

A man's fame, good or bad, and his honor or dishonor, are names for one of his social selves. The particular social self of a man called his honor is usually the result of one of those splittings of which we have spoken. It is his image in the eyes of his own 'set,' which exalts or condemns him as he conforms or not to certain requirements that may not be made of one in another walk of life. Thus a layman may abandon a city infected with cholera; but a priest or a doctor would think such an act incompatible with his honor. A soldier's honor requires him to fight or to die under circumstances where another man can apologize or run away with no stain upon his social self. A judge, a statesman, are in like manner debarred by the honor of their cloth from entering into pecuniary relations perfectly honorable to persons in private life. Nothing is commoner than to hear people discriminate between their different selves of this sort: "As a man I pity you, but as an official I must show you no mercy"; "As a politician I regard him as an ally, but as a moralist I loathe him"; etc., etc. What may be called 'club-opinion' is one of the very strongest forces in life. The thief must not steal from{181} other thieves; the gambler must pay his gambling-debts, though he pay no other debts in the world. The code of honor of fashionable society has throughout history been full of permissions as well as of vetoes, the only reason for following either of which is that so we best serve one of our social selves. You must not lie in general, but you may lie as much as you please if asked about your relations with a lady; you must accept a challenge from an equal, but if challenged by an inferior you may laugh him to scorn: these are examples of what is meant.

The Spiritual Me.—By the 'spiritual me,' so far as it belongs to the empirical self, I mean no one of my passing states of consciousness. I mean rather the entire collection of my states of consciousness, my psychic faculties and dispositions taken concretely. This collection can at any moment become an object to my thought at that moment and awaken emotions like those awakened by any of the other portions of the Me. When we think of ourselves as thinkers, all the other ingredients of our Me seem relatively external possessions. Even within the spiritual Me some ingredients seem more external than others. Our capacities for sensation, for example, are less intimate possessions, so to speak, than our emotions and desires; our intellectual processes are less intimate than our volitional decisions. The more active-feeling states of consciousness are thus the more central portions of the spiritual Me. The very core and nucleus of our self, as we know it, the very sanctuary of our life, is the sense of activity which certain inner states possess. This sense of activity is often held to be a direct revelation of the living substance of our Soul. Whether this be so or not is an ulterior question. I wish now only to lay down the peculiar internality of whatever states possess this quality of seeming to be active. It is as if they went out to meet all the other elements of our experience. In thus feeling about them probably all men agree.{182}

b. The feelings and emotions of self come after the constituents.

Self-appreciation.—This is of two sorts, self-complacency and self-dissatisfaction. 'Self-love' more properly belongs under the division C, of acts, since what men mean by that name is rather a set of motor tendencies than a kind of feeling properly so called.

Language has synonyms enough for both kinds of self-appreciation. Thus pride, conceit, vanity, self-esteem, arrogance, vainglory, on the one hand; and on the other modesty, humility, confusion, diffidence, shame, mortification, contrition, the sense of obloquy, and personal despair. These two opposite classes of affection seem to be direct and elementary endowments of our nature. Associationists would have it that they are, on the other hand, secondary phenomena arising from a rapid computation of the sensible pleasures or pains to which our prosperous or debased personal predicament is likely to lead, the sum of the represented pleasures forming the self-satisfaction, and the sum of the represented pains forming the opposite feeling of shame. No doubt, when we are self-satisfied, we do fondly rehearse all possible rewards for our desert, and when in a fit of self-despair we forebode evil. But the mere expectation of reward is not the self-satisfaction, and the mere apprehension of the evil is not the self-despair; for there is a certain average tone of self-feeling which each one of us carries about with him, and which is independent of the objective reasons we may have for satisfaction or discontent. That is, a very meanly-conditioned man may abound in unfaltering conceit, and one whose success in life is secure, and who is esteemed by all, may remain diffident of his powers to the end.

One may say, however, that the normal provocative of self-feeling is one's actual success or failure, and the good or bad actual position one holds in the world. "He put in his thumb and pulled out a plum, and said, 'What a good{183} boy am I!'" A man with a broadly extended empirical Ego, with powers that have uniformly brought him success, with place and wealth and friends and fame, is not likely to be visited by the morbid diffidences and doubts about himself which he had when he was a boy. "Is not this great Babylon, which I have planted?" Whereas he who has made one blunder after another, and still lies in middle life among the failures at the foot of the hill, is liable to grow all sicklied o'er with self-distrust, and to shrink from trials with which his powers can really cope.

The emotions themselves of self-satisfaction and abasement are of a unique sort, each as worthy to be classed as a primitive emotional species as are, for example, rage or pain. Each has its own peculiar physiognomical expression. In self-satisfaction the extensor muscles are innervated, the eye is strong and glorious, the gait rolling and elastic, the nostril dilated, and a peculiar smile plays upon the lips. This whole complex of symptoms is seen in an exquisite way in lunatic asylums, which always contain some patients who are literally mad with conceit, and whose fatuous expression and absurdly strutting or swaggering gait is in tragic contrast with their lack of any valuable personal quality. It is in these same castles of despair that we find the strongest examples of the opposite physiognomy, in good people who think they have committed 'the unpardonable sin' and are lost forever, who crouch and cringe and slink from notice, and are unable to speak aloud or look us in the eye. Like fear and like anger, in similar morbid conditions, these opposite feelings of Self may be aroused with no adequate exciting cause. And in fact we ourselves know how the barometer of our self-esteem and confidence rises and falls from one day to another through causes that seem to be visceral and organic rather than rational, and which certainly answer to no corresponding variations in the esteem in which we are held by our friends.{184}

c. Self-seeking and self-preservation come next.

These words cover a large number of our fundamental instinctive impulses. We have those of bodily self-seeking, those of social self-seeking, and those of spiritual self-seeking.

Bodily Self-seeking.—All the ordinary useful reflex actions and movements of alimentation and defence are acts of bodily self-preservation. Fear and anger prompt to acts that are useful in the same way. Whilst if by self-seeking we mean the providing for the future as distinguished from maintaining the present, we must class both anger and fear, together with the hunting, the acquisitive, the home-constructing and the tool-constructing instincts, as impulses to self-seeking of the bodily kind. Really, however, these latter instincts, with amativeness, parental fondness, curiosity and emulation, seek not only the development of the bodily Me, but that of the material Me in the widest possible sense of the word.

Our social self-seeking, in turn, is carried on directly through our amativeness and friendliness, our desire to please and attract notice and admiration, our emulation and jealousy, our love of glory, influence, and power, and indirectly through whichever of the material self-seeking impulses prove serviceable as means to social ends. That the direct social self-seeking impulses are probably pure instincts is easily seen. The noteworthy thing about the desire to be 'recognized' by others is that its strength has so little to do with the worth of the recognition computed in sensational or rational terms. We are crazy to get a visiting-list which shall be large, to be able to say when any one is mentioned, "Oh! I know him well," and to be bowed to in the street by half the people we meet. Of course distinguished friends and admiring recognition are the most desirable—Thackeray somewhere asks his readers to confess whether it would not give each of them an exquisite pleasure to be met walking down Pall Mall with a duke on either arm. But in default of dukes{185} and envious salutions almost anything will do for some of us; and there is a whole race of beings to-day whose passion is to keep their names in the newspapers, no matter under what heading, 'arrivals and departures,' 'personal paragraphs,' 'interviews,'—gossip, even scandal, will suit them if nothing better is to be had. Guiteau, Garfield's assassin, is an example of the extremity to which this sort of craving for the notoriety of print may go in a pathological case. The newspapers bounded his mental horizon; and in the poor wretch's prayer on the scaffold, one of the most heart-felt expressions was: "The newspaper press of this land has a big bill to settle with thee, O Lord!"

Not only the people but the places and things I know enlarge my Self in a sort of metaphoric social way. 'Ça me connaît,' as the French workman says of the implement he can use well. So that it comes about that persons for whose opinion we care nothing are nevertheless persons whose notice we woo; and that many a man truly great, many a woman truly fastidious in most respects, will take a deal of trouble to dazzle some insignificant cad whose whole personality they heartily despise.

Under the head of spiritual self-seeking ought to be included every impulse towards psychic progress, whether intellectual, moral, or spiritual in the narrow sense of the term. It must be admitted, however, that much that commonly passes for spiritual self-seeking in this narrow sense is only material and social self-seeking beyond the grave. In the Mohammedan desire for paradise and the Christian aspiration not to be damned in hell, the materiality of the goods sought is undisguised. In the more positive and refined view of heaven, many of its goods, the fellowship of the saints and of our dead ones, and the presence of God, are but social goods of the most exalted kind. It is only the search of the redeemed inward nature, the spotlessness from sin, whether here or hereafter, that can count as spiritual self-seeking pure and undefiled.{186}

But this broad external review of the facts of the life of the Me will be incomplete without some account of the

Rivalry and Conflict of the Different Mes.—With most objects of desire, physical nature restricts our choice to but one of many represented goods, and even so it is here. I am often confronted by the necessity of standing by one of my empirical selves and relinquishing the rest. Not that I would not, if I could, be both handsome and fat and well dressed, and a great athlete, and make a million a year, be a wit, a bon-vivant, and a lady-killer, as well as a philosopher; a philanthropist, statesman, warrior, and African explorer, as well as a 'tone-poet' and saint. But the thing is simply impossible. The millionaire's work would run counter to the saint's; the bon-vivant and the philanthropist would trip each other up; the philosopher and the lady-killer could not well keep house in the same tenement of clay. Such different characters may conceivably at the outset of life be alike possible to a man. But to make any one of them actual, the rest must more or less be suppressed. So the seeker of his truest, strongest, deepest self must review the list carefully, and pick out the one on which to stake his salvation. All other selves thereupon become unreal, but the fortunes of this self are real. Its failures are real failures, its triumphs real triumphs, carrying shame and gladness with them. This is as strong an example as there is of that selective industry of the mind on which I insisted some pages back (p. 173 ff.). Our thought, incessantly deciding, among many things of a kind, which ones for it shall be realities, here chooses one of many possible selves or characters, and forthwith reckons it no shame to fail in any of those not adopted expressly as its own.

So we have the paradox of a man shamed to death because he is only the second pugilist or the second oarsman in the world. That he is able to beat the whole population of the globe minus one is nothing; he has 'pitted' himself to beat that one; and as long as he doesn't{187} do that nothing else counts. He is to his own regard as if he were not, indeed he is not. Yonder puny fellow, however, whom every one can beat, suffers no chagrin about it, for he has long ago abandoned the attempt to 'carry that line,' as the merchants say, of self at all. With no attempt there can be no failure; with no failure, no humiliation. So our self-feeling in this world depends entirely on what we back ourselves to be and do. It is determined by the ratio of our actualities to our supposed potentialities; a fraction of which our pretensions are the denominator and the numerator our success: thus,

Such a fraction may be increased as well by diminishing the denominator as by increasing the numerator. To give up pretensions is as blessed a relief as to get them gratified; and where disappointment is incessant and the struggle unending, this is what men will always do. The history of evangelical theology, with its conviction of sin, its self-despair, and its abandonment of salvation by works, is the deepest of possible examples, but we meet others in every walk of life. There is the strangest lightness about the heart when one's nothingness in a particular line is once accepted in good faith. All is not bitterness in the lot of the lover sent away by the final inexorable 'No.' Many Bostonians, crede experto (and inhabitants of other cities, too, I fear), would be happier women and men to-day, if they could once for all abandon the notion of keeping up a Musical Self, and without shame let people hear them call a symphony a nuisance. How pleasant is the day when we give up striving to be young,—or slender! Thank God! we say, those illusions are gone. Everything added to the Self is a burden as well as a pride. A certain man who lost every penny during our civil war went and actually rolled in the dust, saying he had not felt so free and happy since he was born.{188}

Once more, then, our self-feeling is in our power. As Carlyle says: "Make thy claim of wages a zero, then hast thou the world under thy feet. Well did the wisest of our time write, it is only with renunciation that life, properly speaking, can be said to begin."

Neither threats nor pleadings can move a man unless they touch some one of his potential or actual selves. Only thus can we, as a rule, get a 'purchase' on another's will. The first care of diplomatists and monarchs and all who wish to rule or influence is, accordingly, to find out their victim's strongest principle of self-regard, so as to make that the fulcrum of all appeals. But if a man has given up those things which are subject to foreign fate, and ceased to regard them as parts of himself at all, we are well-nigh powerless over him. The Stoic receipt for contentment was to dispossess yourself in advance of all that was out of your own power,—then fortune's shocks might rain down unfelt. Epictetus exhorts us, by thus narrowing and at the same time solidifying our Self to make it invulnerable: "I must die; well, but must I die groaning too? I will speak what appears to be right, and if the despot says, 'Then I will put you to death,' I will reply, 'When did I ever tell you that I was immortal? You will do your part, and I mine; it is yours to kill, and mine to die intrepid; yours to banish, mine to depart untroubled.' How do we act in a voyage? We choose the pilot, the sailors, the hour. Afterwards comes a storm. What have I to care for? My part is performed. This matter belongs to the pilot. But the ship is sinking; what then have I to do? That which alone I can do—submit to being drowned without fear, without clamor or accusing of God, but as one who knows that what is born must likewise die."

This Stoic fashion, though efficacious and heroic enough in its place and time, is, it must be confessed, only possible as an habitual mood of the soul to narrow and unsympathetic characters. It proceeds altogether by exclusion. If I am a Stoic, the goods I cannot appropriate cease to be my{189} goods, and the temptation lies very near to deny that they are goods at all. We find this mode of protecting the Self by exclusion and denial very common among people who are in other respects not Stoics. All narrow people intrench their Me, they retract it,—from the region of what they cannot securely possess. People who don't resemble them, or who treat them with indifference, people over whom they gain no influence, are people on whose existence, however meritorious it may intrinsically be, they look with chill negation, if not with positive hate. Who will not be mine I will exclude from existence altogether; that is, as far as I can make it so, such people shall be as if they were not. Thus may a certain absoluteness and definiteness in the outline of my Me console me for the smallness of its content.

Sympathetic people, on the contrary, proceed by the entirely opposite way of expansion and inclusion. The outline of their self often gets uncertain enough, but for this the spread of its content more than atones. Nil humani a me alienum. Let them despise this little person of mine, and treat me like a dog, I shall not negate them so long as I have a soul in my body. They are realities as much as I am. What positive good is in them shall be mine too, etc., etc. The magnanimity of these expansive natures is often touching indeed. Such persons can feel a sort of delicate rapture in thinking that, however sick, ill-favored, mean-conditioned, and generally forsaken they may be, they yet are integral parts of the whole of this brave world, have a fellow's share in the strength of the dray-horses, the happiness of the young people, the wisdom of the wise ones, and are not altogether without part or lot in the good fortunes of the Vanderbilts and the Hohenzollerns themselves. Thus either by negating or by embracing, the Ego may seek to establish itself in reality. He who, with Marcus Aurelius, can truly say, "O Universe, I wish all that thou wishest," has a self from which every trace of negativeness and obstructiveness has been removed—no wind can blow except to fill its sails.{190}

The Hierarchy of the Mes.—A tolerably unanimous opinion ranges the different selves of which a man may be 'seized and possessed,' and the consequent different orders of his self-regard, in an hierarchical scale, with the bodily me at the bottom, the spiritual me at top, and the extra-corporeal material selves and the various social selves between. Our merely natural self-seeking would lead us to aggrandize all these selves; we give up deliberately only those among them which we find we cannot keep. Our unselfishness is thus apt to be a 'virtue of necessity'; and it is not without all show of reason that cynics quote the fable of the fox and the grapes in describing our progress therein. But this is the moral education of the race; and if we agree in the result that on the whole the selves we can keep are the intrinsically best, we need not complain of being led to the knowledge of their superior worth in such a tortuous way.

Of course this is not the only way in which we learn to subordinate our lower selves to our higher. A direct ethical judgment unquestionably also plays its part, and last, not least, we apply to our own persons judgments originally called forth by the acts of others. It is one of the strangest laws of our nature that many things which we are well satisfied with in ourselves disgust us when seen in others. With another man's bodily 'hoggishness' hardly anyone has any sympathy; almost as little with his cupidity, his social vanity and eagerness, his jealousy, his despotism, and his pride. Left absolutely to myself I should probably allow all these spontaneous tendencies to luxuriate in me unchecked, and it would be long before I formed a distinct notion of the order of their subordination. But having constantly to pass judgment on my associates, I come ere long to see, as Herr Horwicz says, my own lusts in the mirror of the lusts of others, and to think about them in a very different way from that in which I simply feel. Of course, the moral generalities which from childhood have been instilled into me accelerate{191} enormously the advent of this reflective judgment on myself.

So it comes to pass that, as aforesaid, men have arranged the various selves which they may seek in an hierarchical scale according to their worth. A certain amount of bodily selfishness is required as a basis for all the other selves. But too much sensuality is despised, or at best condoned on account of the other qualities of the individual. The wider material selves are regarded as higher than the immediate body. He is esteemed a poor creature who is unable to forego a little meat and drink and warmth and sleep for the sake of getting on in the world. The social self as a whole, again, ranks higher than the material self as a whole. We must care more for our honor, our friends, our human ties, than for a sound skin or wealth. And the spiritual self is so supremely precious that, rather than lose it, a man ought to be willing to give up friends and good fame, and property, and life itself.

In each kind of Me, material, social, and spiritual, men distinguish between the immediate and actual, and the remote and potential, between the narrower and the wider view, to the detriment of the former and the advantage of the latter. One must forego a present bodily enjoyment for the sake of one's general health; one must abandon the dollar in the hand for the sake of the hundred dollars to come; one must make an enemy of his present interlocutor if thereby one makes friends of a more valued circle; one must go without learning and grace and wit, the better to compass one's soul's salvation.

Of all these wider, more potential selves, the potential social Me is the most interesting, by reason of certain apparent paradoxes to which it leads in conduct, and by reason of its connection with our moral and religious life. When for motives of honor and conscience I brave the condemnation of my own family, club, and 'set'; when, as a Protestant, I turn Catholic; as a Catholic, freethinker; as a 'regular practitioner,' homœopath, or what not, I am{192} always inwardly strengthened in my course and steeled against the loss of my actual social self by the thought of other and better possible social judges than those whose verdict goes against me now. The ideal social self which I thus seek in appealing to their decision may be very remote: it may be represented as barely possible. I may not hope for its realization during my lifetime; I may even expect the future generations, which would approve me if they knew me, to know nothing about me when I am dead and gone. Yet still the emotion that beckons me on is indubitably the pursuit of an ideal social self, of a self that is at least worthy of approving recognition by the highest possible judging companion, if such companion there be. This self is the true, the intimate, the ultimate, the permanent me which I seek. This judge is God, the Absolute Mind, the 'Great Companion.' We hear, in these days of scientific enlightenment, a great deal of discussion about the efficacy of prayer; and many reasons are given us why we should not pray, whilst others are given us why we should. But in all this very little is said of the reason why we do pray, which is simply that we cannot help praying. It seems probable that, in spite of all that 'science' may do to the contrary, men will continue to pray to the end of time, unless their mental nature changes in a manner which nothing we know should lead us to expect. The impulse to pray is a necessary consequence of the fact that whilst the innermost of the empirical selves of a man is a Self of the social sort, it yet can find its only adequate Socius in an ideal world.

All progress in the social Self is the substitution of higher tribunals for lower; this ideal tribunal is the highest; and most men, either continually or occasionally, carry a reference to it in their breast. The humblest outcast on this earth can feel himself to be real and valid by means of this higher recognition. And, on the other hand, for most of us, a world with no such inner refuge when the outer social self failed and dropped from us would be{193} the abyss of horror. I say 'for most of us,' because it is probable that individuals differ a good deal in the degree in which they are haunted by this sense of an ideal spectator. It is a much more essential part of the consciousness of some men than of others. Those who have the most of it are possibly the most religious men. But I am sure that even those who say they are altogether without it deceive themselves, and really have it in some degree. Only a non-gregarious animal could be completely without it. Probably no one can make sacrifices for 'right,' without to some degree personifying the principle of right for which the sacrifice is made, and expecting thanks from it. Complete social unselfishness, in other words, can hardly exist; complete social suicide hardly occur to a man's mind. Even such texts as Job's, "Though He slay me, yet will I trust Him," or Marcus Aurelius's, "If gods hate me and my children, there is a reason for it," can least of all be cited to prove the contrary. For beyond all doubt Job revelled in the thought of Jehovah's recognition of the worship after the slaying should have been done; and the Roman emperor felt sure the Absolute Reason would not be all indifferent to his acquiescence in the gods' dislike. The old test of piety, "Are you willing to be damned for the glory of God?" was probably never answered in the affirmative except by those who felt sure in their heart of hearts that God would 'credit' them with their willingness, and set more store by them thus than if in His unfathomable scheme He had not damned them at all.

Teleological Uses of Self-interest.—On zoölogical principles it is easy to see why we have been endowed with impulses of self-seeking and with emotions of self-satisfaction and the reverse. Unless our consciousness were something more than cognitive, unless it experienced a partiality for certain of the objects, which, in succession, occupy its ken, it could not long maintain itself in existence; for, by an inscrutable necessity, each human mind's appearance on this earth is conditioned upon the integrity{194} of the body with which it belongs, upon the treatment which that body gets from others, and upon the spiritual dispositions which use it as their tool, and lead it either towards longevity or to destruction. Its own body, then, first of all, its friends next, and finally its spiritual dispositions, MUST be the supremely interesting objects for each human mind. Each mind, to begin with, must have a certain minimum of selfishness in the shape of instincts of bodily self-seeking in order to exist. This minimum must be there as a basis for all farther conscious acts, whether of self-negation or of a selfishness more subtle still. All minds must have come, by the way of the survival of the fittest, if by no directer path, to take an intense interest in the bodies to which they are yoked, altogether apart from any interest in the pure Ego which they also possess.

And similarly with the images of their person in the minds of others. I should not be extant now had I not become sensitive to looks of approval or disapproval on the faces among which my life is cast. Looks of contempt cast on other persons need affect me in no such peculiar way. My spiritual powers, again, must interest me more than those of other people, and for the same reason. I should not be here at all unless I had cultivated them and kept them from decay. And the same law which made me once care for them makes me care for them still.

All these three things form the natural Me. But all these things are objects, properly so called, to the thought which at any time may be doing the thinking; and if the zoölogical and evolutionary point of view is the true one, there is no reason why one object might not arouse passion and interest as primitively and instinctively as any other. The phenomenon of passion is in origin and essence the same, whatever be the target upon which it is discharged; and what the target actually happens to be is solely a question of fact. I might conceivably be as much fascinated, and as primitively so, by the care of my neighbor's body as by the care of my own. I am thus fascinated{195} by the care of my child's body. The only check to such exuberant non-egoistic interests is natural selection, which would weed out such as were very harmful to the individual or to his tribe. Many such interests, however, remain unweeded out—the interest in the opposite sex, for example, which seems in mankind stronger than is called for by its utilitarian need; and alongside of them remain interests, like that in alcoholic intoxication, or in musical sounds, which, for aught we can see, are without any utility whatever. The sympathetic instincts and the egoistic ones are thus coördinate. They arise, so far as we can tell, on the same psychologic level. The only difference between them is that the instincts called egoistic form much the larger mass.

Summary.—The following table may serve for a summary of what has been said thus far. The empirical life of Self is divided, as below, into

The I, or 'pure ego,' is a very much more difficult subject of inquiry than the Me. It is that which at any given moment is conscious, whereas the Me is only one of the things which it is conscious of. In other words, it is{196} the Thinker; and the question immediately comes up, what is the thinker? Is it the passing state of consciousness itself, or is it something deeper and less mutable? The passing state we have seen to be the very embodiment of change (see p. 155 ff.). Yet each of us spontaneously considers that by 'I,' he means something always the same. This has led most philosophers to postulate behind the passing state of consciousness a permanent Substance or Agent whose modification or act it is. This Agent is the thinker; the 'state' is only its instrument or means. 'Soul,' 'transcendental Ego,' 'Spirit,' are so many names for this more permanent sort of Thinker. Not discriminating them just yet, let us proceed to define our idea of the passing state of consciousness more clearly.

The Unity of the Passing Thought.—Already, in speaking of 'sensations,' from the point of view of Fechner's idea of measuring them, we saw that there was no ground for calling them compounds. But what is true of sensations cognizing simple qualities is also true of thoughts with complex objects composed of many parts. This proposition unfortunately runs counter to a wide-spread prejudice, and will have to be defended at some length. Common-sense, and psychologists of almost every school, have agreed that whenever an object of thought contains many elements, the thought itself must be made up of just as many ideas, one idea for each element, all fused together in appearance, but really separate.

"There can be no difficulty in admitting that association does form the ideas of an indefinite number of individuals into one complex idea," says James Mill, "because it is an acknowledged fact. Have we not the idea of an army? And is not that precisely the ideas of an indefinite number of men formed into one idea?"

Similar quotations might be multiplied, and the reader's own first impressions probably would rally to their support. Suppose, for example, he thinks that "the pack of cards is on the table." If he begins to reflect, he is as{197} likely as not to say: "Well, isn't that a thought of the pack of cards? Isn't it of the cards as included in the pack? Isn't it of the table? And of the legs of the table as well? Hasn't my thought, then, all these parts—one part for the pack and another for the table? And within the pack-part a part for each card, as within the table-part a part for each leg? And isn't each of these parts an idea? And can thought, then, be anything but an assemblage or pack of ideas, each answering to some element of what it knows?"

Plausible as such considerations may seem, it is astonishing how little force they have. In assuming a pack of ideas, each cognizant of some one element of the fact one has assumed, nothing has been assumed which knows the whole fact at once. The idea which, on the hypothesis of the pack of ideas, knows, e.g., the ace of spades must be ignorant of the leg of the table, since to account for that knowledge another special idea is by the same hypothesis invoked; and so on with the rest of the ideas, all equally ignorant of each other's objects. And yet in the actual living human mind what knows the cards also knows the table, its legs, etc., for all these things are known in relation to each other and at once. Our notion of the abstract numbers eight, four, two is as truly one feeling of the mind as our notion of simple unity. Our idea of a couple is not a couple of ideas. "But," the reader may say, "is not the taste of lemonade composed of that of lemon plus that of sugar?" No! I reply, this is taking the combining of objects for that of feelings. The physical lemonade contains both the lemon and the sugar, but its taste does not contain their tastes; for if there are any two things which are certainly not present in the taste of lemonade, those are the pure lemon-sour on the one hand and the pure sugar-sweet on the other. These tastes are absent utterly. A taste somewhat like both of them is there, but that is a distinct state of mind altogether.

Distinct mental states cannot 'fuse.' But not only is{198} the notion that our ideas are combinations of smaller ideas improbable, it is logically unintelligible; it leaves out the essential features of all the 'combinations' which we actually know.

All the 'combinations' which we actually know are EFFECTS, wrought by the units said to be 'combined,' UPON SOME ENTITY OTHER THAN THEMSELVES. Without this feature of a medium or vehicle, the notion of combination has no sense.

In other words, no possible number of entities (call them as you like, whether forces, material particles, or mental elements) can sum themselves together. Each remains, in the sum, what it always was; and the sum itself exists only for a bystander who happens to overlook the units and to apprehend the sum as such; or else it exists in the shape of some other effect on an entity external to the sum itself. When H₂ and O are said to combine into 'water,' and thenceforward to exhibit new properties, the 'water' is just the old atoms in the new position, H-O-H; the 'new properties' are just their combined effects, when in this position, upon external media, such as our sense-organs and the various reagents on which water may exert its properties and be known. Just so, the strength of many men may combine when they pull upon one rope, of many muscular fibres when they pull upon one tendon.

In the parallelogram of forces, the 'forces' do not combine themselves into the diagonal resultant; a body is needed on which they may impinge, to exhibit their resultant effect. No more do musical sounds combine per se into concords or discords. Concord and discord are names for their combined effects on that external medium, the ear.

Where the elemental units are supposed to be feelings, the case is in no wise altered. Take a hundred of them, shuffle them and pack them as close together as you can (whatever that may mean); still each remains the same{199} feeling it always was, shut in its own skin, windowless, ignorant of what the other feelings are and mean. There would be a hundred-and-first feeling there, if, when a group or series of such feelings were set up, a consciousness belonging to the group as such should emerge, and this one hundred and first feeling would be a totally new fact. The one hundred original feelings might, by a curious physical law, be a signal for its creation, when they came together—we often have to learn things separately before we know them as a sum—but they would have no substantial identity with the new feeling, nor it with them; and one could never deduce the one from the others, or (in any intelligible sense) say that they evolved it out of themselves.

Take a sentence of a dozen words, and take twelve men and tell to each one word. Then stand the men in a row or jam them in a bunch, and let each think of his word as intently as he will: nowhere will there be a consciousness of the whole sentence. We talk, it is true, of the 'spirit of the age,' and the 'sentiment of the people,' and in various ways we hypostatize 'public opinion.' But we know this to be symbolic speech, and never dream that the spirit, opinion, or sentiment constitutes a consciousness other than, and additional to, that of the several individuals whom the words 'age,' 'people,' or 'public' denote. The private minds do not agglomerate into a higher compound mind. This has always been the invincible contention of the spiritualists against the associationists in Psychology. The associationists say the mind is constituted by a multiplicity of distinct 'ideas' associated into a unity. There is, they say, an idea of a, and also an idea of b. Therefore, they say, there is an idea of a + b, or of a and b together. Which is like saying that the mathematical square of a plus that of b is equal to the square of a + b, a palpable untruth. Idea of a + idea of b is not identical with idea of (a + b). It is one, they are two; in it, what knows a also knows b; in them, what knows a is expressly posited as not knowing b; etc. In short, the two separate ideas{200} can never by any logic be made to figure as one idea. If one idea (of a + b, for example) come as a matter of fact after the two separate ideas (of a and of b), then we must hold it to be as direct a product of the later conditions as the two separate ideas were of the earlier conditions.

The simplest thing, therefore, if we are to assume the existence of a stream of consciousness at all, would be to suppose that things that are known together are known in single pulses of that stream. The things may be many, and may occasion many currents in the brain. But the psychic phenomenon correlative to these many currents is one integral 'state,' transitive or substantive (see p. 161), to which the many things appear.

The Soul as a Combining Medium.—The spiritualists in philosophy have been prompt to see that things which are known together are known by one something, but that something, they say, is no mere passing thought, but a simple and permanent spiritual being on which many ideas combine their effects. It makes no difference in this connection whether this being be called Soul, Ego, or Spirit, in either case its chief function is that of a combining medium. This is a different vehicle of knowledge from that in which we just said that the mystery of knowing things together might be most simply lodged. Which is the real knower, this permanent being, or our passing state? If we had other grounds, not yet considered, for admitting the Soul into our psychology, then getting there on those grounds, she might turn out to be the knower too. But if there be no other grounds for admitting the Soul, we had better cling to our passing 'states' as the exclusive agents of knowledge; for we have to assume their existence anyhow in psychology, and the knowing of many things together is just as well accounted for when we call it one of their functions as when we call it a reaction of the Soul. Explained it is not by either conception, and has to figure in psychology as a datum that is ultimate.{201}

But there are other alleged grounds for admitting the Soul into psychology, and the chief of them is

The Sense of Personal Identity.—In the last chapter it was stated (see p. 154) that the thoughts which we actually know to exist do not fly about loose, but seem each to belong to some one thinker and not to another. Each thought, out of a multitude of other thoughts of which it may think, is able to distinguish those which belong to it from those which do not. The former have a warmth and intimacy about them of which the latter are completely devoid, and the result is a Me of yesterday, judged to be in some peculiarly subtle sense the same with the I who now make the judgment. As a mere subjective phenomenon the judgment presents no special mystery. It belongs to the great class of judgments of sameness; and there is nothing more remarkable in making a judgment of sameness in the first person than in the second or the third. The intellectual operations seem essentially alike, whether I say 'I am the same as I was,' or whether I say 'the pen is the same as it was, yesterday.' It is as easy to think this as to think the opposite and say 'neither of us is the same.' The only question which we have to consider is whether it be a right judgment. Is the sameness predicated really there?

Sameness in the Self as Known.—If in the sentence "I am the same that I was yesterday," we take the 'I' broadly, it is evident that in many ways I am not the same. As a concrete Me, I am somewhat different from what I was: then hungry, now full; then walking, now at rest; then poorer, now richer; then younger, now older; etc. And yet in other ways I am the same, and we may call these the essential ways. My name and profession and relations to the world are identical, my face, my faculties and store of memories, are practically indistinguishable, now and then. Moreover the Me of now and the Me of then are continuous: the alterations were gradual and never affected the whole of me at once. So far, then, my personal identity is{202} just like the sameness predicated of any other aggregate thing. It is a conclusion grounded either on the resemblance in essential respects, or on the continuity of the phenomena compared. And it must not be taken to mean more than these grounds warrant, or treated as a sort of metaphysical or absolute Unity in which all differences are overwhelmed. The past and present selves compared are the same just so far as they are the same, and no farther. They are the same in kind. But this generic sameness coexists with generic differences just as real; and if from the one point of view I am one self, from another I am quite as truly many. Similarly of the attribute of continuity: it gives to the self the unity of mere connectedness, or unbrokenness, a perfectly definite phenomenal thing—but it gives not a jot or tittle more.

Sameness in the Self as Knower.—But all this is said only of the Me, or Self as known. In the judgment 'I am the same,' etc., the 'I' was taken broadly as the concrete person. Suppose, however, that we take it narrowly, as the Thinker, as 'that to which' all the concrete determinations of the Me belong and are known: does there not then appear an absolute identity at different times? That something which at every moment goes out and knowingly appropriates the Me of the past, and discards the non-me as foreign, is it not a permanent abiding principle of spiritual activity identical with itself wherever found?

That it is such a principle is the reigning doctrine both of philosophy and common-sense, and yet reflection finds it difficult to justify the idea. If there were no passing states of consciousness, then indeed we might suppose an abiding principle, absolutely one with itself, to be the ceaseless thinker in each one of us. But if the states of consciousness be accorded as realities, no such 'substantial' identity in the thinker need be supposed. Yesterday's and to-day's states of consciousnesses have no substantial identity, for when one is here the other is irrevocably dead and gone. But they have a functional identity, for both{203} know the same objects, and so far as the by-gone me is one of those objects, they react upon it in an identical way, greeting it and calling it mine, and opposing it to all the other things they know. This functional identity seems really the only sort of identity in the thinker which the facts require us to suppose. Successive thinkers, numerically distinct, but all aware of the same past in the same way, form an adequate vehicle for all the experience of personal unity and sameness which we actually have. And just such a train of successive thinkers is the stream of mental states (each with its complex object cognized and emotional and selective reaction thereupon) which psychology treated as a natural science has to assume (see p. 2).

The logical conclusion seems then to be that the states of consciousness are all that psychology needs to do her work with. Metaphysics or theology may prove the Soul to exist; but for psychology the hypothesis of such a substantial principle of unity is superfluous.

How the I appropriates the Me.—But why should each successive mental state appropriate the same past Me? I spoke a while ago of my own past experiences appearing to me with a 'warmth and intimacy' which the experiences thought of by me as having occurred to other people lack. This leads us to the answer sought. My present Me is felt with warmth and intimacy. The heavy warm mass of my body is there, and the nucleus of the 'spiritual me,' the sense of intimate activity (p. 184), is there. We cannot realize our present self without simultaneously feeling one or other of these two things. Any other object of thought which brings these two things with it into consciousness will be thought with a warmth and an intimacy like those which cling to the present me.

Any distant object which fulfils this condition will be thought with such warmth and intimacy. But which distant objects do fulfil the condition, when represented?

Obviously those, and only those, which fulfilled it when they were alive. Them we shall still represent with the{204} animal warmth upon them; to them may possibly still cling the flavor of the inner activity taken in the act. And by a natural consequence, we shall assimilate them to each other and to the warm and intimate self we now feel within us as we think, and separate them as a collection from whatever objects have not this mark, much as out of a herd of cattle let loose for the winter on some wide Western prairie the owner picks out and sorts together, when the round-up comes in the spring, all the beasts on which he finds his own particular brand. Well, just such objects are the past experiences which I now call mine. Other men's experiences, no matter how much I may know about them, never bear this vivid, this peculiar brand. This is why Peter, awakening in the same bed with Paul, and recalling what both had in mind before they went to sleep, reidentifies and appropriates the 'warm' ideas as his, and is never tempted to confuse them with those cold and pale-appearing ones which he ascribes to Paul. As well might he confound Paul's body, which he only sees, with his own body, which he sees but also feels. Each of us when he awakens says, Here's the same old Me again, just as he says, Here's the same old bed, the same old room, the same old world.

And similarly in our waking hours, though each pulse of consciousness dies away and is replaced by another, yet that other, among the things it knows, knows its own predecessor, and finding it 'warm,' in the way we have described, greets it, saying: "Thou art mine, and part of the same self with me." Each later thought, knowing and including thus the thoughts that went before, is the final receptacle—and appropriating them is the final owner—of all that they contain and own. As Kant says, it is as if elastic balls were to have not only motion but knowledge of it, and a first ball were to transmit both its motion and its consciousness to a second, which took both up into its consciousness and passed them to a third, until the last ball held all that the other balls had held, and realized it{205} as its own. It is this trick which the nascent thought has of immediately taking up the expiring thought and 'adopting' it, which leads to the appropriation of most of the remoter constituents of the self. Who owns the last self owns the self before the last, for what possesses the possessor possesses the possessed. It is impossible to discover any verifiable features in personal identity which this sketch does not contain, impossible to imagine how any transcendent principle of Unity (were such a principle there) could shape matters to any other result, or be known by any other fruit, than just this production of a stream of consciousness each successive part of which should know, and knowing, hug to itself and adopt, all those that went before,—thus standing as the representative of an entire past stream with which it is in no wise to be identified.

Mutations and Multiplications of the Self.—The Me, like every other aggregate, changes as it grows. The passing states of consciousness, which should preserve in their succession an identical knowledge of its past, wander from their duty, letting large portions drop from out of their ken, and representing other portions wrong. The identity which we recognize as we survey the long procession can only be the relative identity of a slow shifting in which there is always some common ingredient retained. The commonest element of all, the most uniform, is the possession of some common memories. However different the man may be from the youth, both look back on the same childhood and call it their own.

Thus the identity found by the I in its Me is only a loosely construed thing, an identity 'on the whole,' just like that which any outside observer might find in the same assemblage of facts. We often say of a man 'he is so changed one would not know him'; and so does a man, less often, speak of himself. These changes in the Me, recognized by the I, or by outside observers, may be grave or slight. They deserve some notice here.{206}

The mutations of the Self may be divided into two main classes:

a. Alterations of memory; and

b. Alterations in the present bodily and spiritual selves.

a. Of the alterations of memory little need be said—they are so familiar. Losses of memory are a normal incident in life, especially in advancing years, and the person's me, as 'realized,' shrinks pari passu with the facts that disappear. The memory of dreams and of experiences in the hypnotic trance rarely survives.

False memories, also, are by no means rare occurrences, and whenever they occur they distort our consciousness of our Me. Most people, probably, are in doubt about certain matters ascribed to their past. They may have seen them, may have said them, done them, or they may only have dreamed or imagined they did so. The content of a dream will oftentimes insert itself into the stream of real life in a most perplexing way. The most frequent source of false memory is the accounts we give to others of our experiences. Such accounts we almost always make both more simple and more interesting than the truth. We quote what we should have said or done, rather than what we really said or did; and in the first telling we may be fully aware of the distinction. But ere long the fiction expels the reality from memory and reigns in its stead alone. This is one great source of the fallibility of testimony meant to be quite honest. Especially where the marvellous is concerned, the story takes a tilt that way, and the memory follows the story.

b. When we pass beyond alterations of memory to abnormal alterations in the present self we have graver disturbances. These alterations are of three main types, but our knowledge of the elements and causes of these changes of personality is so slight that the division into types must not be regarded as having any profound significance. The types are:{207}

α. In insanity we often have delusions projected into the past, which are melancholic or sanguine according to the character of the disease. But the worst alterations of the self come from present perversions of sensibility and impulse which leave the past undisturbed, but induce the patient to think that the present Me is an altogether new personage. Something of this sort happens normally in the rapid expansion of the whole character, intellectual as well as volitional, which takes place after the time of puberty. The pathological cases are curious enough to merit longer notice.

The basis of our personality, as M. Ribot says, is that feeling of our vitality which, because it is so perpetually present, remains in the background of our consciousness.

"It is the basis because, always present, always acting, without peace or rest, it knows neither sleep nor fainting, and lasts as long as life itself, of which it is one form. It serves as a support to that self-conscious me which memory constitutes, it is the medium of association among its other parts.... Suppose now that it were possible at once to change our body and put another into its place: skeleton, vessels, viscera, muscles, skin, everything made new, except the nervous system with its stored-up memory of the past. There can be no doubt that in such a case the afflux of unaccustomed vital sensations would produce the gravest disorders. Between the old sense of existence engraved on the nervous system, and the new one acting with all the intensity of its reality and novelty, there would be irreconcilable contradiction."

What the particular perversions of the bodily sensibility may be which give rise to these contradictions is, for the most part, impossible for a sound-minded person to conceive.{208} One patient has another self that repeats all his thoughts for him. Others, amongst whom are some of the first characters in history, have internal dæmons who speak with them and are replied to. Another feels that someone 'makes' his thoughts for him. Another has two bodies, lying in different beds. Some patients feel as if they had lost parts of their bodies, teeth, brain, stomach, etc. In some it is made of wood, glass, butter, etc. In some it does not exist any longer, or is dead, or is a foreign object quite separate from the speaker's self. Occasionally, parts of the body lose their connection for consciousness with the rest, and are treated as belonging to another person and moved by a hostile will. Thus the right hand may fight with the left as with an enemy. Or the cries of the patient himself are assigned to another person with whom the patient expresses sympathy. The literature of insanity is filled with narratives of such illusions as these. M. Taine quotes from a patient of Dr. Krishaber an account of sufferings, from which it will be seen how completely aloof from what is normal a man's experience may suddenly become:

"After the first or second day it was for some weeks impossible to observe or analyze myself. The suffering—angina pectoris—was too overwhelming. It was not till the first days of January that I could give an account to myself of what I experienced.... Here is the first thing of which I retain a clear remembrance. I was alone, and already a prey to permanent visual trouble, when I was suddenly seized with a visual trouble infinitely more pronounced. Objects grew small and receded to infinite distances—men and things together. I was myself immeasurably far away. I looked about me with terror and astonishment; the world was escaping from me.... I remarked at the same time that my voice was extremely far away from me, that it sounded no longer as if mine. I struck the ground with my foot, and perceived its resistance; but this resistance seemed illusory—not that the{209} soil was soft, but that the weight of my body was reduced to almost nothing.... I had the feeling of being without weight...." In addition to being so distant, "objects appeared to me flat. When I spoke with anyone, I saw him like an image cut out of paper with no relief.... This sensation lasted intermittently for two years.... Constantly it seemed as if my legs did not belong to me. It was almost as bad with my arms. As for my head, it seemed no longer to exist.... I appeared to myself to act automatically, by an impulsion foreign to myself.... There was inside of me a new being, and another part of myself, the old being, which took no interest in the newcomer. I distinctly remember saying to myself that the sufferings of this new being were to me indifferent. I was never really dupe of these illusions, but my mind grew often tired of incessantly correcting the new impressions, and I let myself go and live the unhappy life of this new entity. I had an ardent desire to see my old world again, to get back to my old self. This desire kept me from killing myself.... I was another, and I hated, I despised this other; he was perfectly odious to me; it was certainly another who had taken my form and assumed my functions."[32]

In cases like this, it is as certain that the I is unaltered as that the Me is changed. That is to say, the present Thought of the patient is cognitive of both the old Me and the new, so long as its memory holds good. Only, within that objective sphere which formerly lent itself so simply to the judgment of recognition and of egoistic appropriation, strange perplexities have arisen. The present and the past, both seen therein, will not unite. Where is my old Me? What is this new one? Are they the same? Or have I two? Such questions, answered by whatever theory the patient is able to conjure up as plausible, form the beginning of his insane life.{210}

β. The phenomenon of alternating personality in its simplest phases seems based on lapses of memory. Any man becomes, as we say, inconsistent with himself if he forgets his engagements, pledges, knowledges, and habits; and it is merely a question of degree at what point we shall say that his personality is changed. But in the pathological cases known as those of double or alternate personality the loss of memory is abrupt, and is usually preceded by a period of unconsciousness or syncope lasting a variable length of time. In the hypnotic trance we can easily produce an alteration of the personality, either by telling the subject to forget all that has happened to him since such or such a date, in which case he becomes (it may be) a child again, or by telling him he is another altogether imaginary personage, in which case all facts about himself seem for the time being to lapse from out his mind, and he throws himself into the new character with a vivacity proportionate to the amount of histrionic imagination which he possesses. But in the pathological cases the transformation is spontaneous. The most famous case, perhaps, on record is that of Félida X., reported by Dr. Azam of Bordeaux. At the age of fourteen this woman began to pass into a 'secondary' state characterized by a change in her general disposition and character, as if certain 'inhibitions,' previously existing, were suddenly removed. During the secondary state she remembered the first state, but on emerging from it into the first state she remembered nothing of the second. At the age of forty-four the duration of the secondary state (which was on the whole superior in quality to the original state) had gained upon the latter so much as to occupy most of her time. During it she remembers the events belonging to the original state, but her complete oblivion of the secondary state when the original state recurs is often very distressing to her, as, for example, when the transition takes place in a carriage on her way to a funeral, and she has no idea which one of her friends may be dead. She actually became{211} pregnant during one of her early secondary states, and during her first state had no knowledge of how it had come to pass. Her distress at these blanks of memory is sometimes intense and once drove her to attempt suicide.

M. Pierre Janet describes a still more remarkable case as follows: "Léonie B., whose life sounds more like an improbable romance than a genuine history, has had attacks of natural somnambulism since the age of three years. She has been hypnotized constantly by all sorts of persons from the age of sixteen upwards, and she is now forty-five. Whilst her normal life developed in one way in the midst of her poor country surroundings, her second life was passed in drawing-rooms and doctors' offices, and naturally took an entirely different direction. To-day, when in her normal state, this poor peasant woman is a serious and rather sad person, calm and slow, very mild with every one, and extremely timid: to look at her one would never suspect the personage which she contains. But hardly is she put to sleep hypnotically when a metamorphosis occurs. Her face is no longer the same. She keeps her eyes closed, it is true, but the acuteness of her other senses supplies their place. She is gay, noisy, restless, sometimes insupportably so. She remains good-natured, but has acquired a singular tendency to irony and sharp jesting. Nothing is more curious than to hear her after a sitting when she has received a visit from strangers who wished to see her asleep. She gives a word-portrait of them, apes their manners, claims to know their little ridiculous aspects and passions, and for each invents a romance. To this character must be added the possession of an enormous number of recollections, whose existence she does not even suspect when awake, for her amnesia is then complete.... She refuses the name of Léonie and takes that of Léontine (Léonie 2) to which her first magnetizers had accustomed her. 'That good woman is not myself,' she says, 'she is too stupid!' To herself, Léontine, or Léonie 2, she attributes all the sensations and all the{212} actions, in a word all the conscious experiences, which she has undergone in somnambulism, and knits them together to make the history of her already long life. To Léonie 1 [as M. Janet calls the waking woman], on the other hand, she exclusively ascribes the events lived through in waking hours. I was at first struck by an important exception to the rule, and was disposed to think that there might be something arbitrary in this partition of her recollections. In the normal state Léonie has a husband and children; but Léonie 2, the somnambulist, whilst acknowledging the children as her own, attributes the husband to 'the other.' This choice was perhaps explicable, but it followed no rule. It was not till later that I learned that her magnetizers in early days, as audacious as certain hypnotizers of recent date, had somnambulized her for her first accouchements, and that she had lapsed into that state spontaneously in the later ones. Léonie 2 was thus quite right in ascribing to herself the children—it was she who had had them, and the rule that her first trance-state forms a different personality was not broken. But it is the same with her second or deepest state of trance. When after the renewed passes, syncope, etc., she reaches the condition which I have called Léonie 3, she is another person still. Serious and grave, instead of being a restless child, she speaks slowly and moves but little. Again she separates herself from the waking Léonie 1. 'A good but rather stupid woman,' she says, 'and not me.' And she also separates herself from Léonie 2: 'How can you see anything of me in that crazy creature?' she says. 'Fortunately I am nothing for her.'"

λ. In 'mediumships' or 'possessions' the invasion and the passing away of the secondary state are both relatively abrupt, and the duration of the state is usually short—i.e., from a few minutes to a few hours. Whenever the secondary state is well developed, no memory for aught that happened during it remains after the primary consciousness{213} comes back. The subject during the secondary consciousness speaks, writes, or acts as if animated by a foreign person, and often names this foreign person and gives his history. In old times the foreign 'control' was usually a demon, and is so now in communities which favor that belief. With us he gives himself out at the worst for an Indian or other grotesquely speaking but harmless personage. Usually he purports to be the spirit of a dead person known or unknown to those present, and the subject is then what we call a 'medium.' Mediumistic possession in all its grades seems to form a perfectly natural special type of alternate personality, and the susceptibility to it in some form is by no means an uncommon gift, in persons who have no other obvious nervous anomaly. The phenomena are very intricate, and are only just beginning to be studied in a proper scientific way. The lowest phase of mediumship is automatic writing, and the lowest grade of that is where the Subject knows what words are coming, but feels impelled to write them as if from without. Then comes writing unconsciously, even whilst engaged in reading or talk. Inspirational speaking, playing on musical instruments, etc., also belong to the relatively lower phases of possession, in which the normal self is not excluded from conscious participation in the performance, though their initiative seems to come from elsewhere. In the highest phase the trance is complete, the voice, language, and everything are changed, and there is no after-memory whatever until the next trance comes. One curious thing about trance-utterances is their generic similarity in different individuals. The 'control' here in America is either a grotesque, slangy, and flippant personage ('Indian' controls, calling the ladies 'squaws,' the men 'braves,' the house a 'wigwam,' etc., etc., are excessively common; or, if he ventures on higher intellectual flights, he abounds in a curiously vague optimistic philosophy-and-water, in which phrases about spirit, harmony, beauty, law, progression, development, etc., keep recurring. It seems{214} exactly as if one author composed more than half of the trance-messages, no matter by whom they are uttered. Whether all sub-conscious selves are peculiarly susceptible to a certain stratum of the Zeitgeist, and get their inspiration from it, I know not; but this is obviously the case with the secondary selves which become 'developed' in spiritualist circles. There the beginnings of the medium trance are indistinguishable from effects of hypnotic suggestion. The subject assumes the rôle of a medium simply because opinion expects it of him under the conditions which are present; and carries it out with a feebleness or a vivacity proportionate to his histrionic gifts. But the odd thing is that persons unexposed to spiritualist traditions will so often act in the same way when they become entranced, speak in the name of the departed, go through the motions of their several death-agonies, send messages about their happy home in the summer-land, and describe the ailments of those present.

I have no theory to publish of these cases, the actual beginning of several of which I have personally seen. I am, however, persuaded by abundant acquaintance with the trances of one medium that the 'control' may be altogether different from any possible waking self of the person. In the case I have in mind, it professes to be a certain departed French doctor; and is, I am convinced, acquainted with facts about the circumstances, and the living and dead relatives and acquaintances, of numberless sitters whom the medium never met before, and of whom she has never heard the names. I record my bare opinion here unsupported by the evidence, not, of course, in order to convert anyone to my view, but because I am persuaded that a serious study of these trance-phenomena is one of the greatest needs of psychology, and think that my personal confession may possibly draw a reader or two into a field which the soidisant 'scientist' usually refuses to explore.[33]

{215}

Review, and Psychological Conclusion.—To sum up this long chapter:—The consciousness of Self involves a stream of thought, each part of which as 'I' can remember those which went before, know the things they knew, and care paramountly for certain ones among them as 'Me,' and appropriate to these the rest. This Me is an empirical aggregate of things objectively known. The I which knows them cannot itself be an aggregate; neither for psychological purposes need it be an unchanging metaphysical entity like the Soul, or a principle like the transcendental Ego, viewed as 'out of time.' It is a thought, at each moment different from that of the last moment, but appropriative of the latter, together with all that the latter called its own. All the experiential facts find their place in this description, unencumbered with any hypothesis save that of the existence of passing thoughts or states of mind.

If passing thoughts be the directly verifiable existents which no school has hitherto doubted them to be, then they are the only 'Knower' of which Psychology, treated as a natural science, need take any account. The only pathway that I can discover for bringing in a more transcendental Thinker would be to deny that we have any such direct knowledge of the existence of our 'states of consciousness' as common-sense supposes us to possess. The existence of the 'states' in question would then be a mere hypothesis, or one way of asserting that there must be a knower correlative to all this known; but the problem who that knower is would have become a metaphysical problem. With the question once stated in these terms, the notion either of a Spirit of the world which thinks through us, or that of a set of individual substantial souls, must be considered as primâ facie on a par with our own 'psychological' solution, and discussed impartially. I myself believe that{216} room for much future inquiry lies in this direction. The 'states of mind' which every psychologist believes in are by no means clearly apprehensible, if distinguished from their objects. But to doubt them lies beyond the scope of our natural-science (see p. 1) point of view. And in this book the provisional solution which we have reached must be the final word: the thoughts themselves are the thinkers.{217}

The Narrowness of Consciousness.—One of the most extraordinary facts of our life is that, although we are besieged at every moment by impressions from our whole sensory surface, we notice so very small a part of them. The sum total of our impressions never enters into our experience, consciously so called, which runs through this sum total like a tiny rill through a broad flowery mead. Yet the physical impressions which do not count are there as much as those which do, and affect our sense-organs just as energetically. Why they fail to pierce the mind is a mystery, which is only named and not explained when we invoke die Enge des Bewusstseins, 'the narrowness of consciousness,' as its ground.

Its Physiological Ground.—Our consciousness certainly is narrow, when contrasted with the breadth of our sensory surface and the mass of incoming currents which are at all times pouring in. Evidently no current can be recorded in conscious experience unless it succeed in penetrating to the hemispheres and filling their pathways by the processes get up. When an incoming current thus occupies the hemispheres with its consequences, other currents are for the time kept out. They may show their faces at the door, but are turned back until the actual possessors of the place are tired. Physiologically, then, the narrowness of consciousness seems to depend on the fact that the activity of the hemispheres tends at all times to be a consolidated and unified affair, determinable now by this current and now by that, but determinable only as a whole. The ideas correlative to the reigning system of processes{218} are those which are said to 'interest' us at the time; and thus that selective character of our attention on which so much stress was laid on pp. 173 ff. appears to find a physiological ground. At all times, however, there is a liability to disintegration of the reigning system. The consolidation is seldom quite complete, the excluded currents are not wholly abortive, their presence affects the 'fringe' and margin of our thought.

Dispersed Attention.—Sometimes, indeed, the normal consolidation seems hardly to exist. At such moments it is possible that cerebral activity sinks to a minimum. Most of us probably fall several times a day into a fit somewhat like this: The eyes are fixed on vacancy, the sounds of the world melt into confused unity, the attention is dispersed so that the whole body is felt, as it were, at once, and the foreground of consciousness is filled, if by anything, by a sort of solemn sense of surrender to the empty passing of time. In the dim background of our mind we know meanwhile what we ought to be doing: getting up, dressing ourselves, answering the person who has spoken to us, trying to make the next step in our reasoning. But somehow we cannot start; the pensée de derrière la tête fails to pierce the shell of lethargy that wraps our state about. Every moment we expect the spell to break, for we know no reason why it should continue. But it does continue, pulse after pulse, and we float with it, until—also without reason that we can discover—an energy is given, something—we know not what—enables us to gather ourselves together, we wink our eyes, we shake our heads, the background-ideas become effective, and the wheels of life go round again.

This is the extreme of what is called dispersed attention. Between this extreme and the extreme of concentrated attention, in which absorption in the interest of the moment is so complete that grave bodily injuries may be unfelt, there are intermediate degrees, and these have been studied experimentally. The problem is known as that of{219} The Span of Consciousness.—How many objects can we attend to at once when they are not embraced in one conceptual system? Prof. Cattell experimented with combinations of letters exposed to the eye for so short a fraction of a second that attention to them in succession seemed to be ruled out. When the letters formed familiar words, three times as many of them could be named as when their combination was meaningless. If the words formed a sentence, twice as many could be caught as when they had no connection. "The sentence was then apprehended as a whole. If not apprehended thus, almost nothing is apprehended of the several words; but if the sentence as a whole is apprehended, then the words appear very distinct."

A word is a conceptual system in which the letters do not enter consciousness separately, as they do when apprehended alone. A sentence flashed at once upon the eye is such a system relatively to its words. A conceptual system may mean many sensible objects, may be translated later into them, but as an actual existent mental state, it does not consist of the consciousnesses of these objects. When I think of the word man as a whole, for instance, what is in my mind is something different from what is there when I think of the letters m, a, and n, as so many disconnected data.

When data are so disconnected that we have no conception which embraces them together it is much harder to apprehend several of them at once, and the mind tends to let go of one whilst it attends to another. Still, within limits this can be avoided. M. Paulhan has experimented on the matter by declaiming one poem aloud whilst he repeated a different one mentally, or by writing one sentence whilst speaking another, or by performing calculations on paper whilst reciting poetry. He found that "the most favorable condition for the doubling of the mind was its simultaneous application to two heterogeneous operations. Two operations of the same sort, two multiplications, two recitations,{220} or the reciting of one poem and writing of another, render the process more uncertain and difficult."

M. Paulhan compared the time occupied by the same two operations done simultaneously or in succession, and found that there was often a considerable gain of time from doing them simultaneously. For instance:

"I multiply 421 312 212 by 2; the operation takes 6 seconds; the recitation of four verses also takes 6 seconds. But the two operations done at once only take 6 seconds, so that there is no loss of time from combining them."

If, then, by the original question, how many objects can we attend to at once, be meant how many entirely disconnected systems or processes can go on simultaneously, the answer is, not easily more than one, unless the processes are very habitual; but then two, or even three, without very much oscillation of the attention. Where, however, the processes are less automatic, as in the story of Julius Cæsar dictating four letters whilst he writes a fifth, there must be a rapid oscillation of the mind from one to the next, and no consequent gain of time.

When the things to be attended to are minute sensations, and when the effort is to be exact in noting them, it is found that attention to one interferes a good deal with the perception of the other. A good deal of fine work has been done in this field by Professor Wundt. He tried to note the exact position on a dial of a rapidly revolving hand, at the moment when a bell struck. Here were two disparate sensations, one of vision, the other of sound, to be noted together. But it was found that in a long and patient research, the eye-impression could seldom or never be noted at the exact moment when the bell actually struck. An earlier or a later point were all that could be seen.

The Varieties of Attention.—Attention may be divided into kinds in various ways. It is either to

a) Objects of sense (sensorial attention); or to{221}

b) Ideal or represented objects (intellectual attention). It is either

c) Immediate; or

d) Derived: immediate, when the topic or stimulus is interesting in itself, without relation to anything else; derived, when it owes its interest to association with some other immediately interesting thing. What I call derived attention has been named 'apperceptive' attention. Furthermore, Attention may be either

e) Passive, reflex, involuntary, effortless; or

f) Active and voluntary.

Voluntary attention is always derived; we never make an effort to attend to an object except for the sake of some remote interest which the effort will serve. But both sensorial and intellectual attention may be either passive or voluntary.

In involuntary attention of the immediate sensorial sort the stimulus is either a sense-impression, very intense, voluminous, or sudden; or it is an instinctive stimulus, a perception which, by reason of its nature rather than its mere force, appeals to some one of our congenital impulses and has a directly exciting quality. In the chapter on Instinct we shall see how these stimuli differ from one animal to another, and what most of them are in man: strange things, moving things, wild animals, bright things, pretty things, metallic things, words, blows, blood, etc., etc., etc.

Sensitiveness to immediately exciting sensorial stimuli characterizes the attention of childhood and youth. In mature age we have generally selected those stimuli which are connected with one or more so-called permanent interests, and our attention has grown irresponsive to the rest. But childhood is characterized by great active energy, and has few organized interests by which to meet new impressions and decide whether they are worthy of notice or not, and the consequence is that extreme mobility of the attention with which we are all familiar in children, and which{222} makes of their first lessons such chaotic affairs. Any strong sensation whatever produces accommodation of the organs which perceive it, and absolute oblivion, for the time being, of the task in hand. This reflex and passive character of the attention which, as a French writer says, makes the child seem to belong less to himself than to every object which happens to catch his notice, is the first thing which the teacher must overcome. It never is overcome in some people, whose work, to the end of life, gets done in the interstices of their mind-wandering.

The passive sensorial attention is derived when the impression, without being either strong or of an instinctively exciting nature, is connected by previous experience and education with things that are so. These things may be called the motives of the attention. The impression draws an interest from them, or perhaps it even fuses into a single complex object with them; the result is that it is brought into the focus of the mind. A faint tap per se is not an interesting sound; it may well escape being discriminated from the general rumor of the world. But when it is a signal, as that of a lover on the window-pane, hardly will it go unperceived. Herbart writes:

"How a bit of bad grammar wounds the ear of the purist! How a false note hurts the musician! or an offence against good manners the man of the world! How rapid is progress in a science when its first principles have been so well impressed upon us that we reproduce them mentally with perfect distinctness and ease! How slow and uncertain, on the other hand, is our learning of the principles themselves, when familiarity with the still more elementary percepts connected with the subject has not given us an adequate predisposition!—Apperceptive attention may be plainly observed in very small children when, hearing the speech of their elders, as yet unintelligible to them, they suddenly catch a single known word here and there, and repeat it to themselves; yes! even in the dog who looks round at us when we speak of him and pronounce{223} his name. Not far removed is the talent which mind-wandering school-boys display during the hours of instruction, of noticing every moment in which the teacher tells a story. I remember classes in which, instruction being uninteresting, and discipline relaxed, a buzzing murmur was always to be heard, which invariably stopped for as long a time as an anecdote lasted. How could the boys, since they seemed to hear nothing, notice when the anecdote began? Doubtless most of them always heard something of the teacher's talk; but most of it had no connection with their previous knowledge and occupations, and therefore the separate words no sooner entered their consciousness than they fell out of it again; but, on the other hand, no sooner did the words awaken old thoughts, forming strongly-connected series with which the new impression easily combined, than out of new and old together a total interest resulted which drove the vagrant ideas below the threshold of consciousness, and brought for a while settled attention into their place."

Involuntary intellectual attention is immediate when we follow in thought a train of images exciting or interesting per se; derived, when the images are interesting only as means to a remote end, or merely because they are associated with something which makes them dear. The brain-currents may then form so solidly unified a system, and the absorption in their object be so deep, as to banish not only ordinary sensations, but even the severest pain. Pascal, Wesley, Robert Hall, are said to have had this capacity. Dr. Carpenter says of himself that "he has frequently begun a lecture whilst suffering neuralgic pain so severe as to make him apprehend that he would find it impossible to proceed; yet no sooner has he by a determined effort fairly launched himself into the stream of thought, than he has found himself continuously borne along without the least distraction, until the end has come, and the attention has been released; when the pain has recurred with a force that has overmastered all resistance,{224} making him wonder how he could have ever ceased to feel it."[34]

Voluntary Attention.—Dr. Carpenter speaks of launching himself by a determined effort. This effort characterizes what we called active or voluntary attention. It is a feeling which everyone knows, but which most people would call quite indescribable. We get it in the sensorial sphere whenever we seek to catch an impression of extreme faintness, be it of sight, hearing, taste, smell, or touch; we get it whenever we seek to discriminate a sensation merged in a mass of others that are similar; we get it whenever we resist the attractions of more potent stimuli and keep our mind occupied with some object that is naturally unimpressive. We get it in the intellectual sphere under exactly similar conditions: as when we strive to sharpen and make distinct an idea which we but vaguely seem to have; or painfully discriminate a shade of meaning from its similars; or resolutely hold fast to a thought so discordant with our impulses that, if left unaided, it would quickly yield place to images of an exciting and impassioned kind. All forms of attentive effort would be exercised at once by one whom we might suppose at a dinner-party resolutely to listen to a neighbor giving him insipid and unwelcome advice in a low voice, whilst all around the guests were loudly laughing and talking about exciting and interesting things.

There is no such thing as voluntary attention sustained for more than a few seconds at a time. What is called sustained voluntary attention is a repetition of successive efforts which bring back the topic to the mind. The topic once brought back, if a congenial one, develops; and if its development is interesting it engages the attention passively for a time. Dr. Carpenter, a moment back, described the stream of thought, once entered, as 'bearing him along.'{225} This passive interest may be short or long. As soon as it flags, the attention is diverted by some irrelevant thing, and then a voluntary effort may bring it back to the topic again; and so on, under favorable conditions, for hours together. During all this time, however, note that it is not an identical object in the psychological sense, but a succession of mutually related objects forming an identical topic only, upon which the attention is fixed. No one can possibly attend continuously to an object that does not change.

Now there are always some objects that for the time being will not develop. They simply go out; and to keep the mind upon anything related to them requires such incessently renewed effort that the most resolute Will ere long gives out and lets its thoughts follow the more stimulating solicitations after it has withstood them for what length of time it can. There are topics known to every man from which he shies like a frightened horse, and which to get a glimpse of is to shun. Such are his ebbing assets to the spendthrift in full career. But why single out the spendthrift, when to every man actuated by passion the thought of interests which negate the passion can hardly for more than a fleeting instant stay before the mind? It is like 'memento mori' in the heydey of the pride of life. Nature rises at such suggestions, and excludes them from the view:—How long, O healthy reader, can you now continue thinking of your tomb?—In milder instances the difficulty is as great, especially when the brain is fagged. One snatches at any and every passing pretext, no matter how trivial or external, to escape from the odiousness of the matter in hand. I know a person, for example, who will poke the fire, set chairs straight, pick dust-specks from the floor, arrange his table, snatch up the newspaper, take down any book which catches his eye, trim his nails, waste the morning anyhow, in short, and all without premeditation,—simply because the only thing he ought to attend to is the preparation of a noonday{226} lesson in formal logic which he detests. Anything but that!

Once more, the object must change. When it is one of sight, it will actually become invisible; when of hearing, inaudible,—if we attend to it too unmovingly. Helmholtz, who has put his sensorial attention to the severest tests, by using his eyes on objects which in common life are expressly overlooked, makes some interesting remarks on this point in his section on retinal rivalry. The phenomenon called by that name is this, that if we look with each eye upon a different picture (as in the annexed stereoscopic slide), sometimes one picture, sometimes the other, or parts of both, will come to consciousness, but hardly ever both combined. Helmholtz now says:

"I find that I am able to attend voluntarily, now to one and now to the other system of lines; and that then this system remains visible alone for a certain time, whilst the other completely vanishes. This happens, for example, whenever I try to count the lines first of one and then of the other system.... But it is extremely hard to chain the attention down to one of the systems for long, unless we associate with our looking some distinct purpose which keeps the activity of the attention perpetually renewed.{227} Such a one is counting the lines, comparing their intervals, or the like. An equilibrium of the attention, persistent for any length of time, is under no circumstances attainable. The natural tendency of attention when left to itself is to wander to ever new things; and so soon as the interest of its object is over, so soon as nothing new is to be noticed there, it passes, in spite of our will, to something else. If we wish to keep it upon one and the same object, we must seek constantly to find out something new about the latter, especially if other powerful impressions are attracting us away."

These words of Helmholtz are of fundamental importance. And if true of sensorial attention, how much more true are they of the intellectual variety! The conditio sine quâ non of sustained attention to a given topic of thought is that we should roll it over and over incessantly and consider different aspects and relations of it in turn. Only in pathological states will a fixed and ever monotonously recurring idea possess the mind.

Genius and Attention.—And now we can see why it is that what is called sustained attention is the easier, the richer in acquisitions and the fresher and more original the mind. In such minds, subjects bud and sprout and grow. At every moment, they please by a new consequence and rivet the attention afresh. But an intellect unfurnished with materials, stagnant, unoriginal, will hardly be likely to consider any subject long. A glance exhausts its possibilities of interest. Geniuses are commonly believed to excel other men in their power of sustained attention. In most of them, it is to be feared, the so-called 'power' is of the passive sort. Their ideas coruscate, every subject branches infinitely before their fertile minds, and so for hours they may be rapt. But it is their genius making them attentive, not their attention making geniuses of them. And, when we come down to the root of the matter, we see that they differ from ordinary men less in the character of their attention than in the nature of the objects upon{228} which it is successively bestowed. In the genius, these form a concatenated series, suggesting each other mutually by some rational law. Therefore we call the attention 'sustained' and the topic of meditation for hours 'the same.' In the common man the series is for the most part incoherent, the objects have no rational bond, and we call the attention wandering and unfixed.

It is probable that genius tends actually to prevent a man from acquiring habits of voluntary attention, and that moderate intellectual endowments are the soil in which we may best expect, here as elsewhere, the virtues of the will, strictly so called, to thrive. But, whether the attention come by grace of genius or by dint of will, the longer one does attend to a topic the more mastery of it one has. And the faculty of voluntarily bringing back a wandering attention over and over again is the very root of judgment, character, and will. No one is compos sui if he have it not. An education which should improve this faculty would be the education par excellence. But it is easier to define this ideal than to give practical directions for bringing it about. The only general pedagogic maxim bearing on attention is that the more interests the child has in advance in the subject, the better he will attend. Induct him therefore in such a way as to knit each new thing on to some acquisition already there; and if possible awaken curiosity, so that the new thing shall seem to come as an answer, or part of an answer, to a question preëxisting in his mind.

The Physiological Conditions of Attention.—These seem to be the following:

1) The appropriate cortical centre must be excited ideationally as well as sensorially, before attention to an object can take place.

2) The sense-organ must then adapt itself to clearest reception of the object, by the adjustment of its muscular apparatus.

3) In all probability a certain afflux of blood to the cortical centre must ensue.{229}

Of this third condition I will say no more, since we have no proof of it in detail, and I state it on the faith of general analogies. Conditions 1) and 2), however, are verifiable; and the best order will be to take the latter first.

The Adaptation of the Sense-organ.—This occurs not only in sensorial but also in intellectual attention to an object.

That it is present when we attend to sensible things is obvious. When we look or listen we accommodate our eyes and ears involuntarily, and we turn our head and body as well; when we taste or smell we adjust the tongue, lips, and respiration to the object; in feeling a surface we move the palpatory organ in a suitable way; in all these acts, besides making involuntary muscular contractions of a positive sort, we inhibit others which might interfere with the result—we close the eyes in tasting, suspend the respiration in listening, etc. The result is a more or less massive organic feeling that attention is going on. This organic feeling we usually treat as part of the sense of our own activity, although it comes in to us from our organs after they are accommodated. Any object, then, if immediately exciting, causes a reflex accommodation of the sense-organ, which has two results—first, the feeling of activity in question; and second, the object's increase in clearness.

But in intellectual attention similar feelings of activity occur. Fechner was the first, I believe, to analyze these feelings, and discriminate them from the stronger ones just named. He writes:

"When we transfer the attention from objects of one sense to those of another, we have an indescribable feeling (though at the same time one perfectly determinate, and reproducible at pleasure), of altered direction or differently localized tension (Spannung). We feel a strain forward in the eyes, one directed sidewise in the ears, increasing with the degree of our attention, and changing according as we look at an object carefully, or listen to something{230} attentively; and we speak accordingly of straining the attention. The difference is most plainly felt when the attention oscillates rapidly between eye and ear; and the feeling localizes itself with most decided difference in regard to the various sense-organs, according as we wish to discriminate a thing delicately by touch, taste, or smell.

"But now I have, when I try to vividly recall a picture of memory or fancy, a feeling perfectly analogous to that which I experience when I seek to apprehend a thing keenly by eye or ear; and this analogous feeling is very differently localized. While in sharpest possible attention to real objects (as well as to after-images) the strain is plainly forwards, and (when the attention changes from one sense to another) only alters its direction between the several external sense-organs, leaving the rest of the head free from strain, the case is different in memory or fancy, for here the feeling withdraws entirely from the external sense-organs, and seems rather to take refuge in that part of the head which the brain fills. If I wish, for example, to recall a place or person, it will arise before me with vividness, not according as I strain my attention forwards, but rather in proportion as I, so to speak, retract it backwards."

In myself the 'backward retraction' which is felt during attention to ideas of memory, etc., seems to be principally constituted by the feeling of an actual rolling outwards and upwards of the eyeballs, such as occurs in sleep, and is the exact opposite of their behavior when we look at a physical thing.

This accommodation of the sense-organ is not, however, the essential process, even in sensorial attention. It is a secondary result which may be prevented from occurring, as certain observations show. Usually, it is true that no object lying in the marginal portions of the field of vision can catch our attention without at the same time 'catching our eye'—that is, fatally provoking such movements of rotation and accommodation as will focus its image{231} on the fovea, or point of greatest sensibility. Practice, however, enables us, with effort, to attend to a marginal object whilst keeping the eyes immovable. The object under these circumstances never becomes perfectly distinct—the place of its image on the retina makes distinctness impossible—but (as anyone can satisfy himself by trying) we become more vividly conscious of it than we were before the effort was made. Teachers thus notice the acts of children in the school-room at whom they appear not to be looking. Women in general train their peripheral visual attention more than men. Helmholtz states the fact so strikingly that I will quote his observation in full. He was trying to combine in a single solid percept pairs of stereoscopic pictures illuminated instantaneously by the electric spark. The pictures were in a dark box which the spark from time to time lighted up; and, to keep the eyes from wandering betweenwhiles, a pin-hole was pricked through the middle of each picture, through which the light of the room came, so that each eye had presented to it during the dark intervals a single bright point. With parallel optical axes these points combined into a single image; and the slightest movement of the eyeballs was betrayed by this image at once becoming double. Helmholtz now found that simple linear figures could, when the eyes were thus kept immovable, be perceived as solids at a single flash of the spark. But when the figures were complicated photographs, many successive flashes were required to grasp their totality.

"Now it is interesting," he says, "to find that, although we keep steadily fixating the pin-holes and never allow their combined image to break into two, we can nevertheless, before the spark comes, keep our attention voluntarily turned to any particular portion we please of the dark field, so as then, when the spark comes, to receive an impression only from such parts of the picture as lie in this region. In this respect, then, our attention is quite independent of the position and accommodation of the eyes,{232} and of any known alteration in these organs, and free to direct itself by a conscious and voluntary effort upon any selected portion of a dark and undifferenced field of view. This is one of the most important observations for a future theory of attention."[35]

The Ideational Excitement of the Centre.—But if the peripheral part of the picture in this experiment be not physically accommodated for, what is meant by its sharing our attention? What happens when we 'distribute' or 'disperse' the latter upon a thing for which we remain unwilling to 'adjust'? This leads us to that second feature in the process, the 'ideational excitement' of which we spoke. The effort to attend to the marginal region of the picture consists in nothing more nor less than the effort to form as clear an IDEA as is possible of what is there portrayed. The idea is to come to the help of the sensation and make it more distinct. It may come with effort, and such a mode of coming is the remaining part of what we know as our attention's 'strain' under the circumstances. Let us show how universally present in our acts of attention is this anticipatory thinking of the thing to which we attend. Mr. Lewes's name of preperception seems the best possible designation for this imagining of an experience before it occurs.

It must as a matter of course be present when the attention is of the intellectual variety, for the thing attended to then is nothing but an idea, an inward reproduction or conception. If then we prove ideal construction of the object to be present in sensorial attention, it will be present everywhere. When, however, sensorial attention is at its height, it is impossible to tell how much of the percept comes from without and how much from within; but if we find that the preparation we make for it always partly consists of the creation of an imaginary duplicate of the object in the mind, that will be enough to establish the point in dispute.{233}

In reaction-time experiments, keeping our mind intent upon the motion about to be made shortens the time. This shortening we ascribed in Chap. VIII to the fact that the signal when it comes finds the motor-centre already charged almost to the explosion-point in advance. Expectant attention to a reaction thus goes with sub-excitement of the centre concerned.

Where the impression to be caught is very weak, the way not to miss it is to sharpen our attention for it by preliminary contact with it in a stronger form. Helmholtz says: "If we wish to begin to observe overtones, it is advisable, just before the sound which is to be analyzed, to sound very softly the note of which we are in search.... If you place the resonator which corresponds to a certain overtone, for example g´ of the sound c, against your ear, and then make the note c sound, you will hear g´ much strengthened by the resonator.... This strengthening by the resonator can be used to make the naked ear attentive to the sound which it is to catch. For when the resonator is gradually removed, the g´ grows weaker; but the attention, once directed to it, holds it now more easily fast, and the observer hears the tone g´ now in the natural unaltered sound of the note with his unaided ear."

Wundt, commenting on experiences of this sort, says that "The same thing is to be noticed in weak or fugitive visual impressions. Illuminate a drawing by electric sparks separated by considerable intervals, and after the first, and often after the second and third spark, hardly anything will be recognized. But the confused image is held fast in memory; each successive illumination completes it; and so at last we attain to a clearer perception. The primary motive to this inward activity proceeds usually from the outer impression itself. We hear a sound in which, from certain associations, we suspect a certain overtone; the next thing is to recall the overtone in memory; and finally we catch it in the sound we hear. Or perhaps we see some mineral substance we have met before; the{234} impression awakens the memory-image, which again more or less completely melts with the impression itself.... Different qualities of impression require disparate adaptations. And we remark that our feeling of the strain of our inward attentiveness increases with every increase in the strength of the impressions on whose perception we are intent."

The natural way of conceiving all this is under the symbolic form of a brain-cell played upon from two directions. Whilst the object excites it from without, other brain-cells arouse it from within. The plenary energy of the brain-cell demands the co-operation of both factors: not when merely present, but when both present and inwardly imagined, is the object fully attended to and perceived.

A few additional experiences will now be perfectly clear. Helmholtz, for instance, adds this observation concerning the stereoscopic pictures lit by the electric spark. "In pictures," he says, "so simple that it is relatively difficult for me to see them double, I can succeed in seeing them double, even when the illumination is only instantaneous, the moment I strive to imagine in a lively way how they ought then to look. The influence of attention is here pure; for all eye-movements are shut out."

Again, writing of retinal rivalry, Helmholtz says:

"It is not a trial of strength between two sensations, but depends on our fixing or failing to fix the attention. Indeed, there is scarcely any phenomenon so well fitted for the study of the causes which are capable of determining the attention. It is not enough to form the conscious intention of seeing first with one eye and then with the other; we must form as clear a notion as possible of what we expect to see. Then it will actually appear."

In Figs. 55 and 56, where the result is ambiguous, we can make the change from one apparent form to the other by imagining strongly in advance the form we wish to see. Similarly in those puzzles where certain lines in a picture form by their combination an object that has no connection{235} with what the picture obviously represents; or indeed in every case where an object is inconspicuous and hard to discern from the background; we may not be able to see it for a long time; but, having once seen it, we can attend to it again whenever we like, on account of the mental duplicate of it which our imagination now bears. In the meaningless French words 'pas de lieu Rhône que nous,' who can recognize immediately the English 'paddle your own canoe'? But who that has once noticed the identity can fail to have it arrest his attention again? When watching for the distant clock to strike, our mind is so filled with its image that at every moment we think we hear the longed-for or dreaded sound. So of an awaited footstep. Every stir in the wood is for the hunter his game; for the fugitive his pursuers. Every bonnet in the street is momentarily taken by the lover to enshroud the head of his idol. The image in the mind is the attention; the preperception is half of the perception of the looked-for thing.

It is for this reason that men have no eyes but for those aspects of things which they have already been taught to discern. Any one of us can notice a phenomenon after it has once been pointed out, which not one in ten thousand could ever have discovered for himself. Even in poetry and the arts, some one has to come and tell us what{236} aspects to single out, and what effects to admire, before our æsthetic nature can 'dilate' to its full extent and never 'with the wrong emotion.' In kindergarten-instruction one of the exercises is to make the children see how many features they can point out in such an object as a flower or a stuffed bird. They readily name the features they know already, such as leaves, tail, bill, feet. But they may look for hours without distinguishing nostrils, claws, scales, etc., until their attention is called to these details; thereafter, however, they see them every time. In short, the only things which we commonly see are those which we preperceive, and the only things which we preperceive are those which have been labelled for us, and the labels stamped into our mind. If we lost our stock of labels we should be intellectually lost in the midst of the world.

Educational Corollaries.—First, to strengthen attention in children who care nothing for the subject they are studying and let their wits go wool-gathering. The interest here must be 'derived' from something that the teacher associates with the task, a reward or a punishment if nothing less internal comes to mind. If a topic awakens no spontaneous attention it must borrow an interest from elsewhere. But the best interest is internal, and we must always try, in teaching a class, to knit our novelties by rational links on to things of which they already have preperceptions. The old and familiar is readily attended to by the mind and helps to hold in turn the new, forming, in Herbartian phraseology, an 'Apperceptionsmasse' for it. Of course the teacher's talent is best shown by knowing what 'Apperceptionsmasse' to use. Psychology can only lay down the general rule.

Second, take that mind-wandering which at a later age may trouble us whilst reading or listening to a discourse. If attention be the reproduction of the sensation from within, the habit of reading not merely with the eye, and of listening not merely with the ear, but of articulating to one's self the words seen or heard, ought to deepen one's{237} attention to the latter. Experience shows that this is the case. I can keep my wandering mind a great deal more closely upon a conversation or a lecture if I actively re-echo to myself the words than if I simply hear them; and I find a number of my students who report benefit from voluntarily adopting a similar course.

Attention and Free Will.—I have spoken as if our attention were wholly determined by neural conditions. I believe that the array of things we can attend to is so determined. No object can catch our attention except by the neural machinery. But the amount of the attention which an object receives after it has caught our mental eye is another question. It often takes effort to keep the mind upon it. We feel that we can make more or less of the effort as we choose. If this feeling be not deceptive, if our effort be a spiritual force, and an indeterminate one, then of course it contributes coequally with the cerebral conditions to the result. Though it introduce no new idea, it will deepen and prolong the stay in consciousness of innumerable ideas which else would fade more quickly away. The delay thus gained might not be more than a second in duration—but that second may be critical; for in the constant rising and falling of considerations in the mind, where two associated systems of them are nearly in equilibrium it is often a matter of but a second more or less of attention at the outset, whether one system shall gain force to occupy the field and develop itself, and exclude the other, or be excluded itself by the other. When developed, it may make us act; and that act may seal our doom. When we come to the chapter on the Will, we shall see that the whole drama of the voluntary life hinges on the amount of attention, slightly more or slightly less, which rival motor ideas may receive. But the whole feeling of reality, the whole sting and excitement of our voluntary life, depends on our sense that in it things are really being decided from one moment to another, and that it is not the dull rattling off of a chain that was{238} forged innumerable ages ago. This appearance, which makes life and history tingle with such a tragic zest, may not be an illusion. Effort may be an original force and not a mere effect, and it may be indeterminate in amount. The last word of sober insight here is ignorance, for the forces engaged are too delicate ever to be measured in detail. Psychology, however, as a would-be 'Science,' must, like every other Science, postulate complete determinism in its facts, and abstract consequently from the effects of free will, even if such a force exist. I shall do so in this book like other psychologists; well knowing, however, that such a procedure, although a methodical device justified by the subjective need of arranging the facts in a simple and 'scientific' form, does not settle the ultimate truth of the free-will question one way or the other.{239}

Different states of mind can mean the same. The function by which we mark off, discriminate, draw a line round, and identify a numerically distinct subject of discourse is called conception. It is plain that whenever one and the same mental state thinks of many things, it must be the vehicle of many conceptions. If it has such a multiple conceptual function, it may be called a state of compound conception.

We may conceive realities supposed to be extra-mental, as steam-engine; fictions, as mermaid; or mere entia rationis, like difference or nonentity. But whatever we do conceive, our conception is of that and nothing else—nothing else, that is, instead of that, though it may be of much else in addition to that. Each act of conception results from our attention's having singled out some one part of the mass of matter-for-thought which the world presents, and from our holding fast to it, without confusion. Confusion occurs when we do not know whether a certain object proposed to us is the same with one of our meanings or not; so that the conceptual function requires, to be complete, that the thought should not only say 'I mean this,' but also say 'I don't mean that.'

Each conception thus eternally remains what it is, and never can become another. The mind may change its states, and its meanings, at different times; may drop one conception and take up another: but the dropped conception itself can in no intelligible sense be said to change into its successor. The paper, a moment ago white, I may now see to be scorched black. But my conception 'white'{240} does not change into my conception 'black.' On the contrary, it stays alongside of the objective blackness, as a different meaning in my mind, and by so doing lets me judge the blackness as the paper's change. Unless it stayed, I should simply say 'blackness' and know no more. Thus, amid the flux of opinions and of physical things, the world of conceptions, or things intended to be thought about, stands stiff and immutable, like Plato's Realm of Ideas.

Some conceptions are of things, some of events, some of qualities. Any fact, be it thing, event, or quality, may be conceived sufficiently for purposes of identification, if only it be singled out and marked so as to separate it from other things. Simply calling it 'this' or 'that' will suffice. To speak in technical language, a subject may be conceived by its denotation, with no connotation, or a very minimum of connotation, attached. The essential point is that it should be re-identified by us as that which the talk is about; and no full representation of it is necessary for this, even when it is a fully representable thing.

In this sense, creatures extremely low in the intellectual scale may have conception. All that is required is that they should recognize the same experience again. A polyp would be a conceptual thinker if a feeling of 'Hollo! thingumbob again!' ever flitted through its mind. This sense of sameness is the very keel and backbone of our consciousness. The same matters can be thought of in different states of mind, and some of these states can know that they mean the same matters which the other states meant. In other words, the mind can always intend, and know when it intends, to think the Same.

Conceptions of Abstract, of Universal, and of Problematic Objects.—The sense of our meaning is an entirely peculiar element of the thought. It is one of those evanescent and 'transitive' facts of mind which introspection cannot turn round upon, and isolate and hold up for examination, as an entomologist passes round an insect on a pin. In the{241} (somewhat clumsy) terminology I have used, it has to do with the 'fringe' of the object, and is a 'feeling of tendency,' whose neural counterpart is undoubtedly a lot of dawning and dying processes too faint and complex to be traced. (See p. 169.) The geometer, with his one definite figure before him, knows perfectly that his thoughts apply to countless other figures as well, and that although he sees lines of a certain special bigness, direction, color, etc., he means not one of these details. When I use the word man in two different sentences, I may have both times exactly the same sound upon my lips and the same picture in my mental eye, but I may mean, and at the very moment of uttering the word and imagining the picture know that I mean, two entirely different things. Thus when I say: "What a wonderful man Jones is!" I am perfectly aware that I mean by man to exclude Napoleon Bonaparte or Smith. But when I say: "What a wonderful thing Man is!" I am equally well aware that I mean no such exclusion. This added consciousness is an absolutely positive sort of feeling, transforming what would otherwise be mere noise or vision into something understood; and determining the sequel of my thinking, the later words and images, in a perfectly definite way.

No matter how definite and concrete the habitual imagery of a given mind may be, the things represented appear always surrounded by their fringe of relations, and this is as integral a part of the mind's object as the things themselves are. We come, by steps with which everyone is sufficiently familiar, to think of whole classes of things as well as of single specimens; and to think of the special qualities or attributes of things as well as of the complete things—in other words, we come to have universals and abstracts, as the logicians call them, for our objects. We also come to think of objects which are only problematic, or not yet definitely representable, as well as of objects imagined in all their details. An object which is problematic is defined by its relations only. We think of a thing{242} about which certain facts must obtain. But we do not yet know how the thing will look when realized—that is, although conceiving it we cannot imagine it. We have in the relations, however, enough to individualize our topic and distinguish it from all the other meanings of our mind. Thus, for example, we may conceive of a perpetual-motion machine. Such a machine is a quæsitum of a perfectly definite kind,—we can always tell whether the actual machines offered us do or do not agree with what we mean by it. The natural possibility or impossibility of the thing never touches the question of its conceivability in this problematic way. 'Round-square,' again, or 'black-white-thing,' are absolutely definite conceptions; it is a mere accident, as far as conception goes, that they happen to stand for things which nature never shows us, and of which we consequently can make no picture.

The nominalists and conceptualists carry on a great quarrel over the question whether "the mind can frame abstract or universal ideas." Ideas, it should be said, of abstract or universal objects. But truly in comparison with the wonderful fact that our thoughts, however different otherwise, can still be of the same, the question whether that same be a single thing, a whole class of things, an abstract quality or something unimaginable, is an insignificant matter of detail. Our meanings are of singulars, particulars, indefinites, problematics, and universals, mixed together in every way. A singular individual is as much conceived when he is isolated and identified away from the rest of the world in my mind, as is the most rarefied and universally applicable quality he may possess—being, for example, when treated in the same way. From every point of view, the overwhelming and portentous character ascribed to universal conceptions is surprising. Why, from Socrates downwards, philosophers should have vied with each other in scorn of the knowledge of the particular, and in adoration of that of the general, is hard to understand, seeing that the more adorable knowledge ought to be{243} that of the more adorable things, and that the things of worth are all concretes and singulars. The only value of universal characters is that they help us, by reasoning, to know new truths about individual things. The restriction of one's meaning, moreover, to an individual thing, probably requires even more complicated brain-processes than its extension to all the instances of a kind; and the mere mystery, as such, of the knowledge, is equally great, whether generals or singulars be the things known. In sum, therefore, the traditional Universal-worship can only be called a bit of perverse sentimentalism, a philosophic 'idol of the cave.'

Nothing can be conceived as the same without being conceived in a novel state of mind. It seems hardly necessary to add this, after what was said on p. 156. Thus, my arm-chair is one of the things of which I have a conception; I knew it yesterday and recognized it when I looked at it. But if I think of it to-day as the same arm-chair which I looked at yesterday, it is obvious that the very conception of it as the same is an additional complication to the thought, whose inward constitution must alter in consequence. In short, it is logically impossible that the same thing should be known as the same by two successive copies of the same thought. As a matter of fact, the thoughts by which we know that we mean the same thing are apt to be very different indeed from each other. We think the thing now substantively, now transitively; now in a direct image, now in one symbol, and now in another symbol; but nevertheless we somehow always do know which of all possible subjects we have in mind. Introspective psychology must here throw up the sponge; the fluctuations of subjective life are too exquisite to be described by its coarse terms. It must confine itself to bearing witness to the fact that all sorts of different subjective states do form the vehicle by which the same is known; and it must contradict the opposite view.{244}

Discrimination versus Association.—On p. 15 I spoke of the baby's first object being the germ out of which his whole later universe develops by the addition of new parts from without and the discrimination of others within. Experience, in other words, is trained both by association and dissociation, and psychology must be writ both in synthetic and in analytic terms. Our original sensible totals are, on the one hand, subdivided by discriminative attention, and, on the other, united with other totals,—either through the agency of our own movements, carrying our senses from one part of space to another, or because new objects come successively and replace those by which we were at first impressed. The 'simple impression' of Hume, the 'simple idea' of Locke are abstractions, never realized in experience. Life, from the very first, presents us with concreted objects, vaguely continuous with the rest of the world which envelops them in space and time, and potentially divisible into inward elements and parts. These objects we break asunder and reunite. We must do both for our knowledge of them to grow; and it is hard to say, on the whole, which we do most. But since the elements with which the traditional associationism performs its constructions—'simple sensations,' namely—are all products of discrimination carried to a high pitch, it seems as if we ought to discuss the subject of analytic attention and discrimination first.

Discrimination defined.—The noticing of any part whatever of our object is an act of discrimination. Already on p. 218 I have described the manner in which we often spontaneously{245} lapse into the undiscriminating state, even with regard to objects which we have already learned to distinguish. Such anæsthetics as chloroform, nitrous oxide, etc., sometimes bring about transient lapses even more total, in which numerical discrimination especially seems gone; for one sees light and hears sound, but whether one or many lights and sounds is quite impossible to tell. Where the parts of an object have already been discerned, and each made the object of a special discriminative act, we can with difficulty feel the object again in its pristine unity; and so prominent may our consciousness of its composition be, that we may hardly believe that it ever could have appeared undivided. But this is an erroneous view, the undeniable fact being that any number of impressions, from any number of sensory sources, falling simultaneously on a mind WHICH HAS NOT YET EXPERIENCED THEM SEPARATELY, will yield a single undivided object to that mind. The law is that all things fuse that can fuse, and that nothing separates except what must. What makes impressions separate is what we have to study in this chapter.

Conditions which favor Discrimination.—I will treat successively of differences:

(1) So far as they are directly felt;

(2) So far as they are inferred;

(3) So far as they are singled out in compounds.

Differences directly felt.—The first condition is that the things to be discriminated must BE different, either in time, place, or quality. In other words, and physiologically speaking, they must awaken neural processes which are distinct. But this, as we have just seen, though an indispensable condition, is not a sufficient condition. To begin with, the several neural processes must be distinct enough. No one can help singling out a black stripe on a white ground, or feeling the contrast between a bass note and a high one sounded immediately after it. Discrimination is here involuntary. But where the objective difference is{246} less, discrimination may require considerable effort of attention to be performed at all.

Secondly, the sensations excited by the differing objects must not fall simultaneously, but must fall in immediate SUCCESSION upon the same organ. It is easier to compare successive than simultaneous sounds, easier to compare two weights or two temperatures by testing one after the other with the same hand, than by using both hands and comparing both at once. Similarly it is easier to discriminate shades of light or color by moving the eye from one to the other, so that they successively stimulate the same retinal tract. In testing the local discrimination of the skin, by applying compass-points, it is found that they are felt to touch different spots much more readily when set down one after the other than when both are applied at once. In the latter case they may be two or three inches apart on the back, thighs, etc., and still feel as if they were set down in one spot. Finally, in the case of smell and taste it is well-nigh impossible to compare simultaneous impressions at all. The reason why successive impression so much favors the result seems to be that there is a real sensation of difference, aroused by the shock of transition from one perception to another which is unlike the first. This sensation of difference has its own peculiar quality, no matter what the terms may be, between which it obtains. It is, in short, one of those transitive feelings, or feelings of relation, of which I treated in a former place (p. 161); and, when once aroused, its object lingers in the memory along with the substantive terms which precede and follow, and enables our judgments of comparison to be made.