The Philosophical Review/Volume 1/The Origin of Pleasure and Pain - Part 1

by Herbert Nichols

THE ORIGIN OF PLEASURE AND PAIN.

I.

IT is difficult to conceive what life would be if pleasure and pain were stricken out. If we go down into biology we find pleasure and pain to be the mainsprings of action. And if we go upward into human aesthetics and ethics, into the motives of individuals and of society, and into the inspirations and faiths of religion, we but more deeply realize at every step the importance of our subject. Pleasure and pain are not the whole of life; but leave them out, and life and the universe no longer have meaning.

Nearly all the greatest thinkers from the beginning of philosophy have grappled with the subject, yet we are inclined to believe that, from the first, no subject has been more profoundly misunderstood. Whatever the standpoint, whether philosophical or physiological, upon one point only, perhaps, has there always been substantially universal agreement; namely, that pleasure and pain are in some way direct and complementary expressions of the general welfare of the individual. From Plato and Aristotle down through Descartes, Leibnitz, Hobbes, Sulzer, Kant, Herbart, Bain, Spencer, Dumont, and Allen — down to the latest articles of Mr. Marshall in Mind, the idea, at base, has ever been the same: The experience, the judgment, the attainment of a perfect or imperfect life; the perfect or imperfect exercise of a faculty; the furtherance or hindrance of some activity; the rise or fall of some vital function, force, or energy. Everywhere pleasure and pain have been looked upon as complementary terms of a single phenomenon, and as the very essence of expression of the rise and fall of our inmost existence. How they should be so or are so, every philosopher, moralist, or physiologist has explained by theories fitted to his own. Of these theories and explanations almost no two agree; upon no subject, perhaps, is there more general disagreement. It would be noteworthy if the one main view regarding our subject, which has received consent and guided consideration from the beginning, should prove to be the one which is radically in error, and which has led to misconception and confusion from the outset. That such is the case is my conviction, and in hope of rectifying this fundamental and important error, this discussion is presented. I trust that the generosity of my readers will discover that the tone of dogmatism assumed throughout is adopted for brevity and explicitness of exposition.

If we open almost any modern text-book of psychology, we shall find mind divided into 'Intellect, Feeling, and Will'; and we shall be told that these are 'three aspects of mind' — that the 'Feelings' are qualia of other mental contents and inseparable from them. We dissent from this view, and hope to substantiate our rejection of it by considering mental phenomena in connection with our biological origin and neurological development. We place pleasure and pain on common footing with our other senses as fundamental elements of mind, and as being based upon separate specific neural activities or 'energies.' And under both aspects, psychic and physical, we hold pleasure and pain to be as separate from each other and from other sense elements as are the latter from one another.

Neural activity in general is of two chief kinds: conscious and unconscious. The conscious activities all display two modes of appearance or intensity: one mode we call 'original sensations' and the other we term 'images,' 'copies,' or 'ideas' of such. Sensations proper result from stimulation of afferent nerves, while images immediately involve only central processes. Here also we place pleasure and pain precisely on a footing with the other senses. All bodily pleasures and pains we shall conceive to be due to separate currents, rising like other sensory nervous activities at their proper nerve terminals in the body, and running thence through their appropriate paths and centres to the cortex. All the 'fainter' forms of pleasure and pain, — those which constitute the agreeable or disagreeable element in all our judgments, emotions, desires, and passions, whether 'sensual,' aesthetic, moral, or religious, — all these we shall explain, on their physical side, by tracing them to the central modes of neurosis corresponding to the similar central processes of seeing and hearing and of thinking in general.

The traditional views of our subject are natural to the historical course and unfolding of human thought. Following the latter, it is easy to see how and why pleasure and pain were set apart as attributes of our other mental elements rather than classed in common with them. On the other hand, the views herein to be offered are in accord with the modern notions of strict correspondence between all psychic phenomena and their neural basis, and of the origin of our whole nervous system, embryonically from a common cell, and biologically through a common process of development. These two truths — the naturalness of the traditional doctrines and of their errors to the historical development of science and of philosophy, and the harmony of the views herein to be advocated with the latest teachings of various sciences in their unanimity — these truths we shall, as we go on, seek to make plain and elucidative of each other.

Bearing our two hypotheses in mind, let us begin with the most immediate kind of evidence and work our way outward. To me a pain, while I have it, is as disparate as the color blue while I see that. With a pin I touch certain points on the back of my hand in the slightest possible manner. Long after the visible touch is made, a sharp definite pain comes swelling in, out of all proportion to the pin-touch and entirely unaccompanied with any other resulting sensation to be discovered by the closest scrutiny. Again, prick harder; the feelings of touch and of pressure will soon vanish, while the sharp pain will remain alone for some seconds. Moreover, when I prick gently, I get slight, when harder, more pain; there is no passing into pleasure, be the touch or pressure on these precise points as gentle as it may be. All this is more evident upon stimulation of certain isolated nerves or nerve trunks mechanically or electrically. Then we frequently have 'floating pains,' which we can neither locate precisely nor attach to some other sensation as its quale. At times even, as may be experienced, pain becomes so excruciating and dominant as to usurp all other mental content or consciousness. All this seems to show that pain is a separate sensation. No doubt we may, at times, have pains simultaneously with other sensations. I may press my hand so as to feel both pain and touch or pressure. But I may as well, at times, experience a sound and a touch.

That pain has a slower rate of nerve conduction than other sensations can be observed even in health. But particularly is this noticeable in certain pathological conditions. In certain cases of tabes dorsalis, if a cold needle be thrust into the patient's skin, he will feel the touch and cold from a half to two seconds before the pain.

Pain also has a separate path through the spinal cord. In certain pathological conditions of the cord, as those caused by lead poisoning, pain is lost to the lower extremities, while the other senses remain intact. Again, under chloroform, the patient will be extremely sensitive to the slightest touch, yet feel no pain from severe pinching, cutting, tearing, or burning within the same area. On the contrary in certain other pathological states pain remains, while susceptibility to all other sensation is lost. If cocaine or menthol be applied to the skin, or ice to the elbow, we can note the constant order in which touch, pressure, heat, and cold each lapse, leaving pain at the end, by itself, it finally going as the others. Thus pain sometimes stays while all the other senses go, and sometimes goes when the other senses stay, which surely looks as if it were not a quale inseparable from the other senses.

As confirmatory of the separate nature of pain, we now have to add the very important testimony of Goldscheider. He reports having discovered and positively demonstrated isolated specific pain nerves. If this be corroborated, it settles beyond question the specific quality of bodily pains or pain sensations. That the demonstration is correct there seems no reason to doubt. Goldscheider is admittedly the greatest living authority in this particular department, and is excelled by none in pains-taking exactness and reliability. His discovery is in line with the results of his other work, all of which have been substantiated by various independent experimenters. It is in line with the general trend of the doctrine of specific energies in our day, and, as we hope to show, in accord with the widest range of facts known regarding our subject in general.

Until the discovery of Goldscheider it seemed quite certain that, if the stimulation were sufficiently intense, pain would rise from nearly all the sensory nerves of the body. No doubt this has given greater foundation to the doctrine that pain is a general attribute of sense than any other supposed physiological fact. It fell in so exactly with the traditions of philosophy and of ethics as to seem to leave no room for suspecting their soundness or for examining further the phenomenon in question. But we now find the evidence going entirely against the view that most of the nerves of sense are painful. Long before Goldscheider's discoveries, it was found that the optic nerve, one of the largest in the body, is but little if at all sensible to pain. Some of the best authorities inclined to the belief that the pain which sometimes appears to come from violent excitation of the optic nerve really was due to simultaneous irritation of portions of the tri-geminus. Then it was found that the other nerves of the major senses were also but indifferently painful, if indeed at all so, due regard being given to the fibres of other nerves in close proximity to or intermingled with the specific nerves in question. All this makes it entirely certain that, if the special sense nerves are painful, the pain is by no means proportioned to the size of the nerve trunk. Yet we should have expected, if pain were a general attribute of all sense, that it would be most prominently developed in and where the sense of which it were an attribute was also most developed — would have developed parallel with its matrix. The reverse is unquestionably the case; and the discovery of specific nerves of pain now makes it probable, if not quite certain, that whatever pain does come from irritation of the other special nerve trunks is due to specific pain fibres interwoven within the same sheath. This intermingling of the fibrils of one nerve with the trunk of another is now known to be common to most nerves. The microscopic nature of these ultimate fibrils is also known. If, then, minute specific nerves of pain exist throughout the body and are gathered up into various nerve trunks, the fact that most sensory nerves do give some pain can no longer seem remarkable, or be counted as evidence that pain is an inseparable or general attribute of the other senses.

The fact that pain rises from intense stimulation of most sensory organs, and that the specific quality of the senses disappears, or apparently is transformed into pain with increased violence of stimulation, is, at first sight, also a pertinent matter. For example, the blinding of sight and the alleged blending into pain under prolonged excitation of violently intense light, looks like a single process passing from one phase into another, rather than like two separate processes. But it is well known that every nerve has its range of excitation. The ear will not respond with sound to a too slow rate of vibration nor to a too rapid rate. If there were fit reasons why it would be better for the nerves of pain to respond to a more violent range of excitation than that which the nerves of the other senses could endure, this fact would throw light on the origin and function of Goldscheider's pain nerves, and also make clear the phenomenon in question. From the theories, which we shall come to later, of the benefits of pain as a warning against violent and injurious influences, this would seem to be the very arrangement and relation between pain and other nerves which most fits both plausibility and the facts. The nerves of sight, sound, heat, and so on, would according to this respond throughout the range to which they had been differentiated. When the more violent range was reached which was injurious to them and beyond which they could not perform their function, there the sight would cease, and the nerves of pain would take up the functions to which they had peculiarly developed because of the fact that they could endure them with benefit to the creature from their warnings. Under such an arrangement it would not be necessary that the two ranges, say of sight and of pain, should wholly exclude each other. It would be well for the warnings to begin before sight was entirely destroyed. Thus the two processes would overlap and slight pains or disagreeablenesses would be felt with certain sights and sounds.

If our theory be correct, the distribution of pain nerves must have much bearing upon the coexcitation of pain with other sensations. If there were no pain fibres in the optic sheath, but only in proximity to sight regions, this would explain why sensations of bodily pain do not accompany ordinary sight; only rare excitations of light, those violent enough to cause influences radiating to adjoining nerve terminals, or some mechanical disturbances upon the eye, as a blow, or some pathological irritation of the eye, would then cause optic pains. On the other hand, where the pain nerves were distributed more intimately with those of certain senses, naturally the association between pain and these senses would be proportionally more frequent and closer. In the skin the nerves of pain are found by Goldscheider to be microscopically interwoven with the nerves of touch, pressure, heat, and cold. In accordance with this is the much greater frequency of occurrence of pain sensations with pinching, pricking, bruising, burning, freezing, and so on, than with sights, sounds, and tastes.

We may go further than this and get a glimpse of why pain nerves are distributed as they are. The number and the nature of our bodily organs are determined in one way by their functions. Why our eyes are on the outside of our body follows from the nature of sight. Why we have two eyes, rather than that our skin should be covered with eyes, is because being able to see at a distance we may turn our bodies in time to use our two eyes efficiently in every direction. Two eyes are therefore sufficient. Now objects at a distance being little likely to be dangerous, it was not necessary that pain nerves should be interwoven with the rods and cones of the retina in a way to be intimately susceptible to the usual functional experiences of the retina. In contrast with this, touch being contact and the dangers of touch being immediate, touch nerves and also pain nerves were demanded from every point of the body, the one to mediate sensations of touch, and the other to warn against the dangers of contact efficiently in every direction. Similar considerations govern the distribution of pains relative to the other organs and senses of the body.

Again, we may note how pain is distributed with reference to its function as a warning against extraordinary influences. Relative to any bodily organ, its ordinary influences are those to which it has been developed; only the extraordinary are dangerous to that function. The ordinary course of blood circulation occasions no pain, but where there is congestion, there will be abnormal tension of tissue and consequent stimulation of the pain nerves terminating therein; terminating there for the purpose of warning against the dangers of disturbed circulation. An unusual blow causes pain; at first by concussion, afterwards by reason of bruised and congested tissue. A cut or tear exposes to mechanical irritation nerve ends which were before protected from such. Unusual heat or cold causes pain, as we hope to show, by unusual expansion or contraction of certain tissues in the skin. The whole system of pain nerves is an adjustment to the working equilibrium of our body. In places not usually disturbed, and where therefore they would be in the way, there they are not found. In places where violence or a disruption of the normal course of things is most imminent, there they are found. It would be difficult, we think, to account for the distribution of our pains in any similar manner upon the doctrine of their being inseparable qualia of other sensations.

It is common that a definite stimulation will at one time cause a certain sensation without pain, and at other times apparently cause precisely similar sensations with varying degrees of pain. Even the same absolute rise of temperature may occasion an increase of warmth feeling, now with an increase and again with a decrease of pain. Lotze has struggled with this inconstant relationship of pain and pleasure 'attributes' to the physical causes of the sensations to which he supposed them to belong. Yet upon any conceivable relationship of mind to physical basis, it seems as incomprehensible as ever how any sensation and an inseparable quale, both dependent simultaneously on the same identical influence, could thus sometimes the one increase while the other diminished, sometimes the reverse, and again both vary together. Rather we should suspect separate processes, psychic and physical, for such variation. And if both processes are separate and independently based, why speak of quale? Or why hunt for some mode of accounting for this particular separate kind of sensation known as pain, other than a mode like that by which we account for all other kinds of sensation; namely, by specific neural activities related to particular modes of stimulation?

That so many kinds of influence cause pain has been used as a proof of its being a general attribute. But we know too little of the final physical process of any sense to give basis to this argument. The same air wave may cause a sound, a 'cold creep,' a feeling of jar, of tickle, of pain, of teeth-on-edge, and perhaps more. But there is no knowing what molecular variations, all dependent on the sound wave, these different sensations were finally correspondent to. It will be a main point, relative to certain doctrines in this discussion, that pain and pleasure are subject to more kinds of influences than the other senses. But this will always mean that more transformations lead up to the final specific form or physical basis of each. In so far as I know, no one denies that pains do come from the same outer influences as give us sight, sound, touch, and so on. There are two main theories for explaining this. One, the traditional doctrine, makes a single nerve mediate, we will say, the touch and the pain or pleasure. The other, the specific energy doctrine, gives to each sensation a separate nerve. The outer influences are the same for both theories, and the resulting feelings are the same. The differences, then, of the theories mainly concern the modes of mediation. Now if we hold to the law, "like effects, like causes," we must say that the physical activities correspondent to a touch or to any other specific sensation must be the same in kind always. To abandon this position is to abandon all sense or reason for any physical basis of mind at all. Therefore as we have every reason to believe that the touch feeling is the same, whether pleasurable or painful, the physical activity concomitant to the touch should also be the same with pain as with pleasure. From which it is plain that the physical activity of the pain or the pleasure should be separate from that of the touch. That is, when we have a touch and a pain we should account for them by two separate distinct processes, and the same for touch and pleasure. In view of this it seems hardly necessary to ask which should be the most reasonable of our two doctrines. According to the traditional view, these separate activities must be supposed to go on in the same nerve simultaneously. By the doctrine of specific nerves, each goes on in a separate nerve. This is the crucial difference between the rival theories.

But the traditional view not only holds that pleasure and pain are inseparable attributes of other sensations, but that they are inverse and excluding complements of each other; that they are two ends or polar aspects of a single phenomenon. One of the most conclusive tests of nerve functions is that, when their terminals are electrically stimulated, each responds with its proper sensation. In this way Goldscheider's pain nerves give pain; and if pleasure and pain are polar complements surely these same nerves ought in some way to give us pleasure, if any nerves should. If some opposite phase of the same kind of stimulation as causes pain should give pleasure say, a gentle and gradually applied current for pleasure in contrast to a sudden and strong current for pain this would be strong evidence for the polar doctrine. But this never happens: these Goldscheider nerves give only pain, however stimulated; most surely do they never give pleasure. This is not a final demonstration against the traditional view, but it is unfortunate for that doctrine that its strongest evidence fails just where it might be expected to appear.

This brings us to the strongest point to be urged against the doctrine of specific nerves for pleasure. Not only will Goldscheider's pain nerves not respond with pleasure to direct stimulation, but neither will any known single nerve in the body do this. No specific nerves of pleasure have yet been found. We must go further than this and declare that no pleasure sensation, in strict conformity with our definition of a sensation, is as yet demonstrable. There is no doubt that we experience pleasures. Those of eating are among the most sensory. But we are not sure that these are immediately due to stimulation of afferent nerves in the mouth or below the mouth. The difference between a sensation of taste and an idea or memory of some taste is marked, and we have no difficulty in deciding between them. But our pleasures are so obscure that I, for one, am not confident that I can distinguish between those which come with our bodily sensations and those which accompany our purely imaginative processes. I cannot say that the pleasure per se of my most enjoyable meal is of quite another order than that which comes from reading a sublime poem. If any certain viand would always taste well, especially if applied to some particular taste bulb or region, or would follow any clear law for any good number of people, as quinine gives bitter from the papillae circumvallatæ for nearly every one — under such conditions for the various senses pleasure would more surely seem to be a sensation proper. But it is doubtful if there be a single form of stimulation common to any sense, to which pleasure as a sensation will respond invariably. Champagne and terrapin are delicious on one occasion, and only nauseous on another. The red and blue of our flag will thrill with delight after absence in foreign lands; the same spread of violent colors will ordinarily be distressing in a painting or in woman's dress. Normal stimulation of the sex-organs is most constant in responsive sensation. But sexual stimulation may be extremely repugnant. All this gives an uncertain and associative aspect to pleasure quite foreign to ordinary sensations and rendering it difficult for us to determine whether they are such. This has given great support to the quale doctrine, yet it is not clear why this variability should have been counted for the inseparability from other senses of pleasure and pain. Surely this difficulty of distinguishing pleasures ought to mark their lack of kinship with bodily pains, which of all sensations are among those most sharply to be recognized and with a 'tang' emphatically unlike that of any form of pleasure. A better cue, however, to the separateness of pain and pleasure under accompaniment of all modes of sense we shall hope to find, presently, in the separateness of their origins and functions.

Preparatory thereto we yet have numerous things to consider. We have noted a correspondence between the bodily distribution of our pains and their functions as warnings. We may now observe a similar relationship between pleasures and their functions. We will not stop here to show the particular physical relationship between our pleasures and our desires, impulses, and motives which will make these functions clearer presently. But, assuming for the present that the function of pleasure is to prompt to certain conduct, we may note that our pleasures are most intense and most constant just in proportion as the act to which they prompt is vital or important. The functions of sex are the most requisite, yet the most precarious, in animal life. The destiny of the race is staked upon a single act performed with great relative infrequency and difficulty. The incitement thereto should be the more unerring and sufficient. Accordingly the pleasures of sex above all others are most instinctive and most pronounced in intensity, in certainty, and in location. Eating is the next most vital of the sensual functions, and the pleasures of eating are next in prominence. Its sensations are located just where they would be most aptly stimulated, and most surely prompt to the needed conduct. If pleasure nerves are the basis of its pleasures, they are placed just where for best service they ought to be placed. Conceive them to be well supplied to the masticating and digestive organs. The alimentary canal cannot of itself go about for food, cannot even swallow. It must be taken to the dining-room and the whole of life's sustenance put into one little hole. A good share of life's conduct must be shaped to this end. By what means is this prompted? When the acts of eating and of digesting are performed, nerves of pleasure are so adjusted in the proper organs as to be stimulated by such normal performances. Their pleasures become associated with the whole line of conduct common to these performances — with the premonitory symptoms usually preceding eating, and with the ordinary processes leading up to their satisfaction. Thus knit up in a way to be revived by the former and to prompt to the latter, they become properly incorporated into the instincts and habits requisite to promote life and to render its continuance possible and certain. And here, as with sex, we find the strength of the pleasures proportional to the vital importance of their functions. The theory of properly distributed specific nerves explains all this with a clearness that the rival theory gives no suggestion of.

Specific nerves also explain another relationship between our pleasures and the various senses which they accompany. The physical processes of some of our sense organs are more delicate than others, while the senses among themselves display no intensive contrasts relative to those shown between their physical processes. Thus sight waves are far more delicate than sound waves and sound waves than mechanical rubbing, but we cannot distinguish any corresponding scale of psychic intensities between sights, sounds, and touch. On the other hand, as we have just seen above, we do observe a scale of intensities for our pleasures, correspondent to those of the influences causing such in the various sense organs. Sight is the 'clearest' of all the senses, its processes the most delicate, its pleasure sensations, if there be such, the most indistinct and uncertain. On the other hand, the pleasures of sex markedly agree with the physical mode of their production, but contrast with the low objective clearness of the accompanying touch sensations. A scaling of the other senses would show a like law. All this is precisely what we should expect of specific nerves having like nature, wherever located, but subjected to various influences of unlike vigor; and it is the inverse of what should be looked for a priori from the quale standpoint — namely, that the more distinct the sensation, the more distinct should be its pleasure quale.

Most of the facts which we have noted for the separateness of pain sensations speak as well for the independence of pleasure. We said a pain was always a pain; so pleasure is always pleasure. All kinds of sensations are at times so feeble and indistinct that we cannot tell of what kind they are. So with some pleasures. But, so soon as we do recognize the quality at all, then as unmistakably do we know it to be pleasure and not pain as we do that heat is not cold; far more quickly than we perceive that smell is not taste or that ocular accommodation is not retinal distance. Whether we ever have pleasures as purely and exclusively filling the focus of attention as some other sensations — as, say, color, sound, or acute pains — is doubtful, though I have seen men who seemed absorbed in the momentary gratification of an unusually fine 'bouquet' or flavor, and have myself been all but entranced by the pure sensuous delight from the rendering of certain music. Some drugs also seem to produce prolonged and heightened states of pure pleasure excitement, accompanied by no likewise prolonged or heightened other sense.

It is commonly emphasized, in presenting the traditional theory of aesthetics, that the stimulations causing pleasure are of the gentle order in contrast with the violent ones of pain. And so they are, but so also are all other sense stimulations. The contrast lies in those of pain being violent, and not in those of pleasure being specially gentle, which they are not necessarily. They may be gentle in sight; those of sex are not gentle. There is a separate reason for these varying intensities everywhere.

Having now roughly looked over general grounds, let us come to closer details with the senses. We have carefully distinguished sensations from their central images or copies. When speaking of 'sight' we ordinarily include in our meaning both sight sensations and sight images. We are so aware of the difference between these that very little confusion comes into our discussions by so doing. But it is of the first importance that we carefully distinguish between the sensations proper of pleasure and pain and the images of such, in untangling the many obscurities of our subject; to nothing is the confusion which has befallen it from the earliest times more due than to lack of this discrimination. As the two orders require entirely separate treatment, it shall be our care to separate the one from the other, and, to begin with, attempt to account only for those sensations pure and proper which now commonly mingle with our other senses. Having so gained such light and data as we may, inasmuch as all copies ought to be traceable to originals of some kind and of some former period however remote (and in instincts they are very remote), we shall then examine how we may account for the far more difficult order of central and aesthetic pains and pleasures.

We are now to hunt for every phenomenon of pleasure or pain due directly to excitation of afferent nerves simultaneously with the stimulation of our other sensations — sight, sound, and so on. Every manner of agreeableness or disagreeableness not strictly of this order we are to throw out into a category of their own, to be explained afterward, yet in a manner entirely in accord with the doctrine of specific pleasure and pain activities. We are well aware of the meagreness of proportion which the aesthetic sensations which we shall discover will bear to the immense bulk of our associative or central aesthetics which we must throw out, but so also does our intellectual life as a whole outmeasure in like proportion the original experiences from which it has sprung.

We will begin with color. We know that light of any color, if sufficiently intense, will cause pain. Our hypothesis of specific pain nerves explains this. But we do not know that light of any single color, and of intensity less than will cause positive bodily pain from abnormal disturbances, will be accompanied normally and invariably either with agreeableness or disagreeableness. Undoubtedly our 'like' or 'dislike' often does accompany certain colors, which otherwise apparently are the sole objects of presentation. But these 'likes' may be indirect results of retinal stimulation. The 'explosion' of the cortex cells which, fired by the retinal currents, give us the color, may overflow to other regions and cells, which, consequently but secondarily, give us the 'like' or 'dislike.' That is, these aesthetics may be associated phenomena such as we are at present to neglect. Let me illustrate. The other day our laboratory received a large pile of "Bradley's Color-Sheets." They present each three or four square feet of uniform tint, and the pile contains a sample of nearly every possible tint and shade. They are exquisite; and a friend having unusual predilections for color delights had for some days been "revelling" in what he termed the "pure sensuous thrill" they gave him. With a purpose in view, I asked him to show me the one he liked best out of perhaps some two or three hundred sheets. He quickly did so, having previously spent much time in selection. I then asked him why he chose that color and tint. He replied, "Oh it is like the friend you trust and the character you admire — so firm and deep" He had told me too much. I was in hunt for an unmistakable pleasure sensation. Had he described some particular thrill "streaming in from every inch of color," or "swelling up the eye-ball," or "creeping up his scalp," or "flooding down his spine," it would have corresponded more with a "sensuous thrill." But, knowing my friend as I do, I at once saw that what he described and what he had felt was a reaction of his character — a response of his stored-up cortical ideas and instincts rather than any immediate response to his retinal processes, as was the mere color.

I do not state this as if to settle our question, but to raise its difficulties. How shall we investigate this problem for men in general? I am not sure that my friend would always pick out the same color. Could I concoct for him some beverage of the same deep liquid hue, but which, being drunk, should throw him into spasms of violent nausea, I feel sure that forever after he would abominate that particular color that it would be peculiarly treacherous and vile to him. If there were any certain color around which clustered the preferences of most persons, — say a majority out of three sets of a thousand each, — this would speak for some intimate relation between the color and the choice. An insufficient number of tests have been made on this plan, but all that have been made fail to show, even approximately, any such constant preference. I believe that a thousand women chosen from the cotton-hands of the South would pick out a lot of violent colors, while a thousand Parisian modistes would choose tints soft and delicate. Should one be so fortunate as to hunt down the determining reasons for the difference of these choices, I am inclined to suspect that it might turn finally on the mere facts of dye-production. Certain dyes have been abundantly and cheaply produced from ancient times. From simple reasons of nature and of science these have been strong simple colors. It is best, for the daily gown of the farm-hand, to be one not easily showing soil, therefore preferably one not of bright color. But Sunday toggery and occasional 'camp-meeting' trimmings could be of brighter hues. The mere neatness and skin-agreeableness, therefore, or the many exciting associations experienced on these exceptional occasions of wearing brighter colors, (in turn none of the æsthetic elements of which associations were retinal,) — these may have thus first determined the 'liking' for them; and, so determined, this preference would thereafter remain attached to them until supplanted by some other associations. The particular kind of bright colors here chosen may thus have depended entirely on the difficulties and historical developments of chemistry. Again for the modiste. I am told by a prominent dye-man that "any one who could discover the manufacture of any strikingly new good and fast fabric dye of any tint or color whatever could get a hundred thousand dollars for the patent to-morrow." Rarity, not some innate charm, seems hinted here. Mere rarity now might not win the modiste's honest preference. But if we consider that for a long time the rare tints have become the complex tints, we may see how rarity by gradual and slow degrees has educated lovers of novelties to prefer soft and delicate colors, — educated them through the pangs and satisfactions of rivalry far more than through the unfolding of any æsthetic process seated in the eye. What is the seat of rivalry we will discuss in proper place, but it is not in the eye.

I feel sure, if the first gift of civilization to a wild Central Africa native should be a shawl of bright red color, that such would appear to her more beautiful than the most delicate mauve in the whole collection of "Bradley's Color-Sheets"; and if the shawl had been mauve, then red would sink into insignificance. I do not know and no one could trace all the primary circumstances which have determined the color likes and dislikes of civilization, but I do see ample room for them to have come down to us through instincts deeply inherited or through associations passed from generation to generation, or acquired in our individual lives, no elements of which ever or anywhere were seated directly in retinal stimulation. To make this difficult subject a little more plain, let me give an extreme illustration. Bright red infuriates a bull. Let us analyze his instincts. Red is the color of blood. The bull has always been a fighter. When he has fought he has seen blood. Bright red has seldom on his native heath and in connection with a moving creature been the object of his attention except to fight it. Through the dust of conflict the lolling tongue or a flowing wound would be the most conspicuous object to guide his aim and attack by. Now, far-fetched origins of instincts are always uncertain, but I can far more readily understand a bull's ordinary conduct toward flaming red on the above explanation than I can by attributing the marked difference between the bull's performances and those of a cow or horse toward the same handkerchief to some difference of retinal physiology, or to some difference of æsthetic temperament or spiritual quale as distributed between bulls and horses.

Perhaps something might be expected to be said here of contrasts, but these seem so plainly to be secondary cortex effects that I dare here to omit them.

Few things are now better known in psychology than that our most ordinary sensations may arouse associations so close that the independent nature of the latter would never be suspected from the mere data of the occurrence. Until Berkeley it was scarcely believed that visual direction was given in terms based upon separate organs from those which give us color. Yet to recognize all this does not wholly solve our problem. Even if we decided that all the æsthetics of color were associative, we have yet to account for the seat and origin of these associations. But we do not wholly so decide. I am a little inclined to think that we may yet at times and under proper circumstances have æsthetic color sensations proper, though we should esteem them to be of comparatively rare occurrence and of little value to the bulk of our aesthetic life. Most of the aesthetics of vision we shall, in proper place, endeavor to account for as associations. Whether we now have pure aesthetic sensations of color will depend, as we hold, on whether there are yet fibres in the retina which will respond directly to ordinary light of any kind with sensations of pain or pleasure. Whether there be any such or not is a matter for investigation. If they be found, certain aesthetic phenomena would be quite in accord with their presence; yet so indistinguishable are our different forms of pleasure to present introspection that no obvious difficulty is presented to accounting for these same phenomena as associations. The kinds of stimulation likely to cause these phenomena may be described as the "pure and massive," — such as would subject a large portion of the retina or of the visual area of the cortex to deep, steady, and prolonged, but not painfully violent stimulation. Such might be a mild flood of light of pure and unmixed color. A landscape or mountain view of deep perspective might do the same. They would be pleasures from sight in general and probably without color preferences. They would suggest summative processes and speak of primitive conditions now somewhat atrophied. Our reasons for suspecting these will appear later.

We now pass to the aesthetics of figure and of perspective. The retina, unlike any other of the so-called sense organs, is a part of the cortex. The cortex is pre-eminently a centre of memories, conscious and unconscious. Rising from the classical discussions of the space problem are reasons to believe that our perceptions of space, figure, and perspective are peculiarly dependent upon developed memories. If it should happen that certain parts of the retina acting as cortex areas were the physical basis of certain memories fundamental to the workings of our eyes as space organs, we ought not to class these memories as sensations. And if mixed among these memories, which though unconscious in the retina should work to rouse corresponding conscious memories in the upper cortex, — if among the latter were memories of pleasure or pain quality, as well as of color or of muscle-sense quality, plainly such aesthetic results should go among our associative class of phenomena to be discussed hereafter.

Of æsthetic sensations proper (pains of abnormal conditions always hereafter excepted) I find no direct trace among the other visual phenomena than color, — none among the lines, the angles, or the perspectives of art or nature. I thrilled with delight when I saw the Venus de Milo, and when I first stood before Cologne Cathedral in full moonlight; but if I note closely I observe it was not the lines nor the angles of these, however grand or perfect, that of themselves directly charmed me. The most perfect line in Venus would not please me if described by the torn entrails of a bull-fighter's hack. It is the ideas associated with visual forms, and called up by them, that determine them aesthetically. I will give another illustration to make this plainer.

In Mind, No. 2 (new series), Professor Bain notes "the unaccountable ratio of increase of aesthetic delight as the points of excellence in art are refined upon." We must ask how our doctrine would account for this, — say, with the Venus. First note that a Congo pigmy would hardly display this ratio — for instance as between Powers's Greek Slave and the Milo. It is a biological fact that symmetry of body culminated with acuteness of intellect and of aesthetic feelings among the Greeks. I strongly suspect that the same secrets of embryological and morphological growth which determined the one likewise determined the other; that the same laws which lead up to symmetrical limbs and features also lead up to symmetry and perfection of other bodily organs; and that with perfection of organs in general goes perfection of neural organs and therefore better mental development. Perhaps in some universe ova and embryos need not grow with bilateral regularity in order to prosper; in this world they must. Show me why the egg cleaves symmetrically and I will tell you better why the strong minds and acute feelings of the Greeks went with their symmetrical bodies. Perfection of curve, perfection of intellect, and perfection of feelings were all expressions of the same biological factor and excellence. Very well then! How could the Greeks help knitting up their æsthetic preferences with the kind of bodies they happened to have had, and with these curves which thus everywhere expressed and suggested such various excellences? I surmise if the limbs and bodies of the Greek maidens had been as crooked and gnarled as those of Rip Van Winkle's dwarfs that specimens of just such sublime crookedness would have to-day occupied the pedestals of the Louvre and the Vatican in place of the symmetrical types now found there. The Greeks were the Greeks and their curves were the beautiful. Why the Greeks were the Greeks and why they had these curves I take to be biology's secret rather than Mr. Ruskin's. Mr. Bain's ratio comes from heightened and increased volume of intellectual associations due to education; the uneducated do not exhibit the ratio.

The mechanism by which our aesthetic associations are knit up, and of what ultimate material, we have yet to consider. We have indicated what of this material is not directly seated in the visual organs. Our theory does not preclude aesthetic nerves and sensations in any of the organs of sight; but they are comparatively unimportant if there, and a matter for detailed investigation. We now pass to hearing.

Unlike color, certain sensations of sound are invariably disagreeable within reasonable conditions for the same person. A like constant agreeableness is doubtful. But first let us examine the disagreeableness. In these few lines I cannot mention the many facts and theories offered in explanation of this matter. They all have value. In general they have demonstrated close mathematical relationship between disagreeable tone combinations and 'beats.' I wish now to extend this relationship to one of 'frequency of occurrence,' and thence to 'use' and 'habit,' and to the influence of such morphologically upon the distribution of specific nerves In the ear. We know there is a direct relationship between use and growth. In experience, tones of certain pitch occur more frequently than those of other pitch. Our vocal apparatus has so developed that we make far more tones of a definite range of pitch than of other tones. This gives as between the different tones a ratio due to 'use.' Again, with sounds from most sources there is a fundamental tone which is strong and a mathematical series of overtones rapidly but proportionally decreasing in strength upwards. There is also a set of 'difference tones' decreasing in strength mathematically downward. The specific organs of all the various tones get exercise in proportion to the strength of the tones they emit. Consequently we have here another ratio, due to use, between the various tones. And it will be observed that these two ratios fall on and supplement each other. The maximum for frequency of exercise falls precisely on that for strength of exercise, and the ratios run together mathematically throughout. We could work out a 'permutation and combination' formula expressing, for the specific organ of each tone of which the ear is capable, its total developmental stimulation, based upon the relationships of frequency and strength of occurrence between usual fundamental tones and the octaves, fifths, fourths, thirds, and so on of their overtones. And it will be observed that the ratios of these would correspond inversely to the disagreeableness of these intervals. But this is precisely what we should expect according to the doctrine of specific nerves. Let us recall here our discussion of pain nerves as warners, and of their distribution with reference to usual functions and working equilibrium. We should not expect to find pain nerves among the cells and fibres mediating the most ordinary sounds. They would be in the way there, and soon crowded out. We should expect to find them crowded in everywhere close up to a margin line, determined as for our above formula by the common uses and experiences of the ear.

Let us seek an illustration that may, perhaps, elucidate all this. Under this doctrine aesthetic modifications would be likely to occur under any marked changes of auditory experience. It is well known that musical 'thirds' was the limit of agreeableness to the Greeks. Handel accepted 'fourths'; Beethoven 'fifths'; while Wagner wove into his compositions every combination of which ordinary musical instruments are capable. Again, we have the Swiss musician who went into exile among the mountains, taking his piano with him, and who, returning after several years, found every other piano painfully out of tune. How shall we explain all this? Not by the length, number, or strength of sound vibrations in the abstract, surely; for these and their mathematical relations are always the same. But to the relations between use and development of specific cells and fibres, and between such development and the distribution of specific pain nerves, the whole set of circumstances is easily reconcilable. With increased study and cultivation of music comes more frequent occurrence of unusual combinations and harmonies. With great and daring musicians the increase of such above the ordinary past experiences of the human race would be considerable, even as a morphological factor. It is fair to suppose that the cells and fibres of tones but infrequently heard before would now tend to develop, — those which involved pain as well as the others. The complicated apparatus of tone cells and fibres would be likely to get far more of the new exercise than would the simpler pain nerve fibres and so develop more and faster. Again, the apparatus for tone outmeasuring in bulk that for pain, even if the increased growth were but proportional to the bulk to be developed, we should soon have the tone apparatus crowding that of pain into atrophy. It is likely that still other conditions of arrangements, spatial and functional, would encourage such a process. Thus we should here have a process corresponding to the culture of music crowding out the pain nerves from tones and combination-tones previously representing the margin of the harmful as developed by the sum of former experiences, the said pain nerves now being useless or, rather, obstructive to the new circumstances of experience. By the early cultivation of music the Greeks had come to hear 'thirds' without discomfort. By a continuation of the same process Handel came to accept 'fourths'; through Beethoven we grew to 'fifths,' and eventually, no doubt, the musical world will find no discomfort in the now, to some, intolerable discords of Wagner. If the above explanations are correct, certain chords not too excessively disagreeable for morphological experiment ought to be modified in æsthetic bearing by continued exercise or hearing of them. This should be made the subject of scientific research. But already in every factory, foundry, and boiler shop is to be found what amounts to experimental confirmation of our theory.

Now for the pleasures of hearing. We have confessed to strong sensuous pleasure from music, but I suspect that the ordinary delights of music originate in the sensations accompanying the movements by which we make vocal sounds, rather than in the ear. We express emotion pre-eminently by the voice. The emotions awakened by music are those expressed by the voice. Whatever the final seat of these emotions, there is a deep and strong association from the ear through the voice to this seat. The crude musician takes more delight in the act of shouting than in the noise he makes. And the cultured musician seems to gain in aesthetic delight rather by expansion of intellectual associations than from new sensations rising from the ear. We may presently find reasons for connecting all our emotions peculiarly with certain primary functions of the body. Among others, with the movements of breathing — abdominal, thoracic, and the aspirative movements in the throat, mouth, lips, and nose. Such emotions as are seated in this class of organs will plainly have connections with those expressed by the voice, and through the voice with the aesthetics of hearing. But these would only make plainer that the great majority of the delights of sounds are not sensations from the ear. Again, as with color, we discover how difficult it is from introspection alone to decide between our two modes of pleasure — whether some of the pleasures of hearing are or are not sensations. To me it is a matter of doubt if there are now, or ever were, any pleasure nerves in the auditory organs. Whether there are such is a matter for exact investigation. If there are such the general nature of the pleasures arising from them, and of the stimulation which may affect them, are sufficiently indicated by what we have already said of the like class under vision. All other pleasures of hearing than these possible sensations we shall class as associations.

Constancy of psychic reaction to apparently constant conditions of stimulation again being our test, we are in as much doubt regarding the æsthetics of taste and smell as we were with sight and hearing. An argument for specific nerves has sometimes been made from the fact that sweets are usually pleasant and bitters disagreeable for most people. But on the one hand the law of specific energies must not be 'usual' but invariable; and, on the other, the law of association does not demand that the results of all sweets should have been beneficial and of all bitters harmful to have given birth to an abstract association of sweet with 'nice' and of bitter with 'bad.' A vast majority of pleasant remembrances of sweet and beneficial viands would outweigh a lot of infrequent experiences of harmful and poisonous substances. The laws of association, therefore, seem best to cover the case.

No taste is always agreeable in the same way that vinegar always tastes sour, and perhaps there is no taste always disagreeable. Should there prove to be any constantly unpleasant tastes they would be accountable to pain nerves so located as to affect us warningly against influences, mechanical or chemical, of or resembling a class on the whole having proved harmful. Again this is a matter for detailed examination. The æsthetics of smell and taste may do without them, and are all associations save these possible exceptions.

We have said that the pleasures of eating are among the most sensuous that we have. We believe these grosser pleasures of eating come from the act of eating rather than from the kind of food eaten; that the precise stimulations causing the taste and the smells do not cause these pleasures. But these pleasures should not be classed here, but with the various sensations — muscular, digestive, tactual, circulatory, or what they may — into which the processes of eating may be analyzed.

We now reach the skin. Among temperature feelings, certain pretty constant reactions indicate æsthetic temperature sensations proper. Goldscheider and several people have demonstrated specific nerves of heat and of cold. Dr. Lombard and others have discovered of the various kinds of tissue in the skin — connective, elastic, and muscular — that some contract while others expand under the same changes of temperature. From their work and from some late experiments of our own with different drugs injected into the skin, we are led to believe that the heat nerves of Goldscheider end in one kind of tissue having one characteristic of temperature contraction, and the cold nerves in another tissue having the opposite characteristic. Also, it would seem that the heat tissues are actively contracting when the cold tissues are either passive or actively expanding, and that the cold tissues are actively contracting only when the heat tissues are passive or expanding. Also, each of these tissues has its range of temperature activity, and each range is complementary to, and exclusive of the other. This will be understood if it be recalled that a common gum band is only actively elastic within a certain range of temperature; if too hot the gum melts, if too cold it is stiff. All this being so, we may easily conceive why our heat and cold sensations from the same area are mutually complementary and exclusive of each other. If now we assume, by way of hypothesis, that both pain and pleasure nerves also end in each of these kinds of tissue, and that each kind of such nerves is susceptible to a peculiar intensive range of stimulation, we may form an idea of how our common temperature comforts and discomforts may be explained thereby. We have indicated certain biological reasons why pain should with benefit respond peculiarly to unusually vigorous stimulations, and why pleasure throughout the various senses should develop in a scale of intensities for the organs of each sense proportionally to the intensities of the forms of stimulation proper to such organs. Indeed it is a proper answer to the question, Why in any particular place or function is a certain sense developed to or limited to any certain range of intensity? to answer, Because it was most needed and most beneficial in that particular place and function that it should be developed to that particular degree and range of intensity. It may be easily understood, then, how pain having developed to warn against too intense temperatures, and pleasure having developed to prompt to certain conduct best suitable to certain moderate degrees of temperature, that they should thus have grown up sensible only to ranges of temperature mutually exclusive of each other. Assigning these ranges somewhat arbitrarily, for present illustration we might now construct the following schema^[1] for our temperature aesthetics. At about -40° F. the heat tissue would be passive, the cold tissue violently active: we should suffer pains of cold. With increase of temperature the cold tissue would relax and its sensations abate; from this cause, at 68° the range of 'cold' pain would run out; at about 70 pleasure nerves start up in cold tissue; at 75° the pleasures of coolness a maximum; at 90° cold tissue so passive as to be affected only by great changes of temperature; consequently no further sensations from cold tissues. Turning to the heat tissue, we should have it beginning ordinary activity at about 60°; here indistinguishable feelings of warmth and agreeableness; 65° maximum of agreeable warmth; 75° pleasure range run out in heat tissue; at 72° pain range beginning to give indistinguishable discomfort; thence upward, heat and pain increase to unbearable limits.

Such a schema shows the pleasure ranges of the two tissues to overlap, and the ranges of pain and pleasure to overlap in each tissue; and in accordance with this, as we know, temperature from 70° to 75° is sometimes pleasurably warm, sometimes pleasurably cool, sometimes disagreeably warm, again disagreeably cool, and more often still is quite indifferent. All this last would be again explainable by two other facts. First, at this indifference region, both tissues would commonly be passive except to sudden changes of considerable extent; consequently no temperature sensations would here be commonly felt. Secondly, the moment of contractile inertia would be different under different conditions, and would depend upon the direction of the immediate changes of temperature with reference to the previous state or direction of the thermometer. The same absolute change of temperature would not feel the same when previously we had been growing warmer as when we had been growing colder. Pleasant coolness from a sudden fall of very high thermometer, and pleasant warmth from a sudden rise from very low thermometer, would be effects of summation. All this about temperature we present tentatively — to be placed on a footing with Hering's theory of color, as most plausible for the present. We would be positive of nothing except that it is more plausible than qualia. Finally, we make the same reservations about temperature as about sight, sound, taste, and smell. There may be no æsthetic sensations of temperature at all and no nerves. Our doctrine of specific pleasure and pain energies would not be wrecked without them. If they exist, the majority of temperature æsthetics are yet associations, and they may all be associations.

Touch should receive more consideration than our space affords, for here we find our most certain evidence of pleasure sensations. Sexual sensations under normal conditions can scarcely be doubted. Some local strokings, scratchings, and ticklings of the skin appear to be more or less constantly agreeable or disagreeable for most people; in certain diseases of the skin these phenomena are yet more markedly agreeable. By some authorities the tickle sense has been expected to prove the very foundation of the pleasure sense. We dissent from this view, but incline to believe that pleasure nerves may yet be discovered in certain regions of the skin.

An important and perhaps special class of sensations comes from the joints, but investigation of these has not yet reached the question of their æsthetics.

The distinction between muscle sense and sense of innervation is now familiar to psychology. As to direct pleasure from the muscles we are in the same doubt as elsewhere. It seems certain that single contractions are ordinarily indifferent. If certain obscure and summative conditions give us normal æsthetic sensations from the muscles, our theory will have room for them. As the relations which muscular activities and the psychic activities of their occurrence bear to the origin and fundamental nature of the æsthetic senses are of major importance in the particular views yet to be put forth in this paper, we shall for expediency postpone further consideration of muscular activities till these views have been stated. Naturally the questions of fatigue, rest, ennui, freshness, and the like are postponed also.

There yet remains to us a perhaps all-important mass of undetermined sensations for lack of knowledge of them usually classed under 'common sensibility.' When we eat, when we are full, when too full, when hungry or thirsty, when freshly active or when resting, when feverish or sickly or chilly, when circulation or digestion is disturbed, — from all parts of the body, on obscure occasions, come a number of peculiar feelings. We have creeps, shivers, shudders, throbbings, flushings, stretchings, crazy-bone prickings, numbness, feelings of emptiness and void, teeth-on-edge,'the carriage-wheel's squeaking-scrape crawling through the whole nervous system, — we have all these sensations, some agreeable and most of them disagreeable, but none of which can be given good account of. We are inclined to believe that many of these involve processes fundamental to the physical basis of our emotions and of peculiar importance to our subject, but insight into them will be easier when happily we have found the key to our æsthetic organization in general. We will only note here that their lack of connection with all other sensations is hard to be reconciled with the doctrine of qualia.

A summary to this point of our very rough sketch is now in order. Nowhere have we found tangible evidence indicating that pleasures and pains are inseparable attributes of other senses or polar complements of each other. It may be urged that we have not looked for it, or sufficiently considered the arguments which have elsewhere been given as such. But we trust that what we have said has not been without bearing on this subject, and we shall return to the point later. The few certain facts we have been able to collate are all unmistakable evidence against the traditional views held of our subject. A considerable amount of proof first and last makes specific pain nerves and separate bodily sensations of pain pretty certain. In one or two regions or processes specific sensations of pleasure seem probable. There is likelihood of them in many places, and no final proof against them anywhere.

The great bulk of our æsthetic feelings unquestionably are associations and of central origin. In view of this, and impressed by the common belief that all central copies or products must at some time have prototype sensations of peripheral origin, it should now be the major concern of any hypothesis offered for the solution of our problem to account for the fundamental origin of the ultimate pain and pleasure elements of our aesthetic associations. To this matter, which I have had in view through all the obscurities and contradictions to which I may seem to have committed myself, we must in the next article address our attention.

Herbert Nichols.

⁠HARVARD UNIVERSITY.

(To be concluded.)

1. This schema may be graphically shown by a drawing with a graded thermometer in the middle; the space to the right of it representing heat tissue; that to the left cold tissue; contrary arrows on each side showing how tissues contract; separate triangles on each side representing each sensation, horizontal length of their bases proportional to intensity and each apex placed at the height where each sensation begins or ends.