We have just shown that the so-called higher forms of emotion do not escape from the necessity of physiological conditions; but there is yet another question, still in obscurity and suspense, which, by reason of its importance, ought to be elucidated. It is this: Why have certain internal or external states, certain images, certain ideas, the privilege of exciting certain organic and motor states, and, in consequence, emotion? How is this connection, this nexus, established? for experience teaches us that it is not necessary: in the same individual the same perception or idea may awaken an emotion, whereas in another case it may produce nothing. In other words, there are perceptions, images, and concepts which remain purely intellectual states without affective accompaniment, at least with none accessible to consciousness. There are others which are immediately enveloped and, as it were, submerged in the emotion which they produce. Let us note that the question comes before us, whatever opinion we may adopt as to the genesis of emotion. As usually accepted, the order is this: intellectual state, affective state, organic states. According to the physiological hypothesis, the order is as follows: intellectual state, organic states, affective state. Passing from one thesis to the other, the problem is subject to but one variation: Why is a certain intellectual state sometimes coupled with an intellectual state, and sometimes not? This is on the first hypothesis. Why is a certain intellectual state sometimes accompanied by organic and motor modifications, sometimes not? This is on the second hypothesis.

The answer is the same in both cases: the intellectual state is accompanied by an affective state whenever there is a direct relation with the conditions of existence, natural or social, of the individual. In order to justify this proposition we must examine in succession these two forms of the conditions of existence.

1st Period.—Sensations or images connected with the natural conditions of existence.

We have here to do with a question of genesis; we must therefore begin with the humblest phenomena. The primordial sense, the only one in certain animals, is touch combined with internal sensations. Let us remark that, in its origin, the “knowledge” which we take in its lowest degree has only a practical value; sensation is a monitor, an aid, an instrument, a weapon with only one aim—the preservation of the individual,—and completely subordinated to that end; otherwise, it is nothing but a useless manifestation, a luxury. The nexus between the sensations and the organic and motor reactions is therefore innate—i.e., it results from the very constitution of the animal. If it fails, the conditions of existence are at fault. The primordial tissue, says Spencer, must be differently affected, according as it is in contact with nutritive matter (ordinarily soluble) or with innutritive matter (ordinarily insoluble). The contraction by which the tactual surface of a rhizopod absorbs a fragment of assimilable matter is caused by a commencing absorption of this matter, i.e., contact and absorption are the same thing. The action of certain agents is followed by a retractile movement, or, on the contrary, by movements of a character to assure the continuance of the impression. These two kinds of movement are, in this writer’s view, respectively the phenomena and the signs of pleasure and pain. The tissue, therefore, acts in such a manner as to assure pleasure and avoid pain, by a law as physical and natural as that by which a magnet turns towards the pole, or a tree to the light. Without inquiring whether pleasure and pain exist in this case—a purely hypothetical assumption—there are, at least, objective phenomena denoting a nexus of utility between the sensation and the expansive or retractile movements.

Passing from these inferior organisms to those provided with several senses, we find no change. Each order of sensation acts in the same way. The animal is better informed, and consequently better protected and armed—that is all. Finally, when certain images (i.e., recollections of pleasures and pains experienced) excite an emotional state, the mechanism remains the same, and tends towards the same end. It is therefore not without reason that we have above assimilated every form of primary emotion to a psycho-physiological organism adapted to a particular end.

It is needless to review the primary emotions and to show that the sensation, the perception, or the image only produces organic or motor troubles when the preservation of the individual or the species is at stake. The intellectual state (sensation, perception, or image) can instinctively—i.e., through an innate mechanism—produce immobility, oppression, withdrawing into one’s self, flight (fear); or, on the contrary, aggressive movements, attack (anger), or movements of attraction, accompanied by phenomena peculiar to each species (sexual love).

To sum up, every event of this kind, reduced to its simplest expression, consists in (1) an intellectual fact, analogous to a spring moving the whole machine, (2) an unconscious, half-conscious, or conscious reaction of the instinct of self-preservation; this being by no means an entity, as we have already said, but the organism itself under its dynamic aspect.

2nd Period.—Perceptions, images, or ideas connected with social conditions of existence.

Up to the present, we have only considered emotional reaction in its relations with nature—i.e., with the physical environment. Its domain is much more extensive; in man, and in many animals, it is adapted to the social environment. At bottom, the mechanism remains the same. A perception, an image, or an idea excites an emotion, because related, directly or indirectly (in the latter case the relation is conceived, inductively or deductively), to the social conditions of the individual. The natural ego has its needs and tendencies; the same is true of the social ego, grafted on the other, or rather, one with it; consequently, the mechanism comes very frequently into play; the circumference is extended, but the centre remains the same.

Let us note the differences between the two periods. In the latter we have (1) a preponderance of representations and concepts—i.e., the superior forms of knowledge; (2) instead of a natural, innate association between certain perceptions and certain emotional reactions—associations which may be called anatomical, because fixed in the individual organism—there are secondary, acquired associations, less solidly fixed, sometimes entirely artificial, which result from experience, from education, from habit, from imitation. I give some examples, by way of elucidation, and in order to avoid repetition.

The feeling of property is derived from a natural condition of existence—nutrition. It is first manifested—in the form of a prevision—in some animals who store up a reserve of food for the future. In primitive man this instinct extends to clothes, weapons, the cave or hut which he inhabits; later on, with the nomadic life, to herds and flocks; then to agricultural products, silver, gold, paper money; finally to that impalpable thing called credit, which has merely an imaginary existence. Thus it gradually takes on a social character. The knowledge of any loss or any gain, actual or possible, produces an emotion in the individual, because it shows him that his adaptation to social conditions is diminished or augmented.

The sentiment of “self-feeling” is innate, primary. Let us imagine ourselves in a society where the questions of rank, precedence, etiquette, are of capital importance—in an aristocratic monarchy like that of Louis XIV.—and we shall see what a ferment of emotions may be raised by an occurrence which, to our eyes, seems futile and irrelevant. If we read Saint-Simon’s Mémoires, we see him boiling over with indignation when a courtier is unduly accorded the privileges of a duke and peer, and his wife is granted a stool in the Queen’s presence. He spends his time in incessant visits, forms coalitions, does all in his power to move the ministers or the Parliament, and finally exults in his victory. However factitious and puerile this agitation may seem, it results from the same physiological mechanism as the simplest emotions: from the instinct of personal preservation—not of his natural ego, but of his ego qua courtier of the Grand Monarque. If he fails, he is injured, depreciated, lessened in his conditions of social existence.

The case already cited, of Malebranche, to whom Descartes’ Traité de l’homme “caused such violent palpitations of the heart that he was obliged continually to leave his book in order to breathe,” called forth Fontenelle’s remark that “Truth, which is invisible and of no practical utility, is not wont to find so much sensibility among men.” No doubt; but to the true man of science the pursuit of truth is one of the necessary conditions of existence. For others it is a mere luxury, to the loss of which they are quite indifferent.

I think we have thus replied to the question previously put—why certain sensations, images, ideas, have the privilege of producing organic and motor changes which, translated into the language of consciousness, constitute the emotional state—and justified our answer. The sensation, the image, the idea, are only occasional causes, incapable by themselves of producing any emotion: it springs from the inmost personality of the individual—from his organisation—expresses it directly, and participates in its stability and its instability.

IV.

The hypothesis of James and Lange—considered, at first, as a paradox—has suggested so many remarks, criticisms, objections, answers, and arguments for and against, that I find it impossible to give a summary of them.^[77] Yet it is not without precedent. Lange, in his Addenda, mentions as his precursors, Malebranche, Spinoza, and some other less celebrated authors. The legitimate claims of Descartes, in his treatise Sur les Passions de l’Âme, have also since been vindicated.^[78] The physiologists, too, ought not to be forgotten: Maudsley indicated the same view, without insisting on it.^[79] The superiority of James and Lange consists in having put it clearly and endeavoured to support it by experimental proofs. I have already said that it seems to me the most probable explanation for those who do not represent the emotions to themselves as psychological entities. The only point in which I differ from these authors relates to their way of putting the proposition, not to its substance.

It is evident that our two authors, whether consciously or not, share the dualist point of view with the common opinion which they are combating; the only difference being in the interversion of cause and effect. Emotion is a cause of which the physical manifestations are the effect, says one party; the physical manifestations are the cause of which emotion is the effect, says the other. In my view, there would be a great advantage in eliminating from the question every notion of cause and effect, every relation of causality, and in substituting for the dualistic position a unitary or monistic one. The Aristotelian formula of matter and form seems to me to meet the case better, if we understand by “matter” the corporeal facts, and by “form” the corresponding psychical state: the two terms, by-the-bye, only existing in connection with each other and being inseparable except as abstract conceptions. It was traditional in ancient psychology to study the relations of “the soul and the body”—the new psychology does not speak of them. In fact, if the question takes a metaphysical form, it is no longer psychology; if it takes an experimental form, there is no reason to treat it separately, because it is treated in connection with everything. No state of consciousness can be dissociated from its physical conditions: they constitute a natural whole, which must be studied as such. Every kind of emotion ought to be considered in this way: all that is objectively expressed by movements of the face and body, by vaso-motor, respiratory, and secretory disturbances, is expressed subjectively by correlative states of consciousness, classed by external observation according to their qualities. It is a single occurrence expressed in two languages. We have previously assimilated the emotions to psycho-physiological organisms; this unitary point of view, being more conformable to the nature of things and to the present tendencies of psychology, seems to me, in practice, to eliminate many objections and difficulties.

Whether we adopt this theory or not, we have in any case acquired the certainty that the organic and motor manifestations are not accessories, that the study of them is part of the study of emotion. We shall therefore have to speak of them in some detail.

Confused state of this question—Popular versus Medical Psychology—Part played by the brain, the centre of psychic life—Hypotheses on the “seat” of the emotions—Part played by the heart, the centre of vegetative life—Popular metaphors and their physiological interpretation—Are the internal sensations reducible to a single process?—Part played by chemical action in the genesis of emotion—Cases of the introduction of toxic substances—Auto-intoxication—Modifications in the course of mental maladies.

As the physiological substratum of emotion, or its material (the reader may use which expression he prefers), comprises the organic or internal functions, and the motor functions showing themselves outwardly, we shall follow this division. Although it may seem artificial, it is not altogether so; the internal manifestations are, for the most part, outside the action of the will; the external manifestations are, in many cases, subject to that action. In any case, this somewhat arbitrary distinction is desirable for the sake of clearness in exposition.

I.

The relation of different emotions to the internal functions is a subject yet in its infancy. Our knowledge of it is still in a vague and confused state. It is at the same point where the problem of the expression of the emotions was before Charles Bell and Darwin; i.e., we have before us a purely empiric set of observed facts without suggested explanation. No doubt it is well known that vaso-motor and respiratory disturbances vary according to the emotions, but the reasons for the differences between one case and another are often unknown and even unexplored. Although Lange has done much in this direction, we cannot congratulate ourselves on having a complete presentation of all the organic and functional manifestations which accompany the simple emotions, not to speak of the complex forms. Still less do we know, clearly and positively, why these and not other manifestations are produced. Thus Hack Tuke asserts it to be a matter of common observation that while the blush of shame begins in the cheeks and the ears, that of anger begins with the eyes, and that of love with the forehead. Supposing this fact to be firmly established, we should still have to find out why, in each case, that particular vascular region should be affected by preference. In short, the study of the external conditions of emotion remains at the present time fragmentary and descriptive.

The part played by the viscera in the emotions and passions is so evident that in all ages it has arrested the attention of mankind. On this point, for a period of several centuries, we find, on the one hand, a popular psychology,—which in all languages has become fixed in the form of metaphors,—full of errors and prejudices, but also of very sound observations; on the other hand, scientific attempts at explanation, varying with the physiology of the period, and expressed in terms of the current medical doctrine. During this long period we can distinguish two principal directions of thought: one tending to localise the passions exclusively in the viscera, especially the heart, the other to place them in the brain. Without distorting facts, we might find in these two tendencies the incomplete and unconscious form of the two reigning theories in affective psychology, the organic and the intellectualist.

It would be of no interest to retrace this long history, to remind the reader that Plato placed courage in the breast and the sensual appetites in the abdomen, that the School of Salerno attributed anger to the gall, joy to the spleen, love to the liver. The organic or visceral theory long had an overwhelming preponderance, and Bichat, at the beginning of the century (1800), did not hesitate to write, “The brain is not affected by the passions which have for their exclusive seat the organs of internal life—the liver, lungs, heart, spleen, etc.” From the seventeenth century downwards, the cerebral theory becomes more accentuated; with Gall and Charles Bell the heart is quite dispossessed, and, by way of reaction, the part played by the viscera was almost forgotten.

At the present day no one maintains that the heart or any other organ is the seat of an emotion in the sense of feeling it; the consciousness of the affective life only exists through the brain, in which the internal sensations coming from the viscera are represented as external sensations; it is an echo. The brain, says Hunter, knows perfectly well that the body has a liver and a stomach, or, as Carus expressed it, each organ has its psychische Signatur. The ideal would be to determine, by means of a complete and well-conducted elementary analysis, the part contributed by each internal organ and function to the constitution of a particular emotion. Nothing of this sort can be attempted: there exist, on this point, only scattered materials and conjectures supported chiefly by the phenomena of morbid states. We shall return to this later on. (See Part II.) Let us at this moment confine our attention to the two predominant organs—the brain, the centre of psychic life; the heart, the centre of vegetative life.

1. The brain is not merely the echo of internal sensations; it receives and reacts according to its disposition; it centralises, but while taking its own part in the concert; it puts its mark on the impressions it receives. Already (Chap. I., § 1) we have seen the theories propounded as to the “seat” or “centre” of pain or pleasure: bulb, protuberance, temporal lobe, occipital lobe, etc. Naturally, each author has extended his hypothesis to the emotions properly so called. However, the search for “emotional centres” appears still more chimerical. A particular emotion has no determinate centre, is not localised in a restricted area of the encephalon. Not only does neither observation nor experience indicate anything of the sort, but if we consider the complexity of any emotion whatever, we shall understand that it requires the activity of several cerebral and infra-cerebral centres: (1) the sensory centres of sight, hearing, smell, etc.; (2) the centres scattered through the motor zone and regulating the movements of different parts of the body; (3) and lastly, the centres corresponding to the phenomena of organic life. These constitute several stages: in the spinal cord, the respiratory centre, that which accelerates the movements of the heart, the genito-spinal, the vesico-spinal (it is well known that the bladder is as good an æsthesiometer as the iris), etc.; in the bulb, the respiratory and vaso-motor centres, and those of cardiac and thermic inhibition. As regards the cortical layer, there are many open questions as to the position of the vascular, thermic, trophic, glandular centres, of the organic movements which determine the contraction of the intestines, the bladder, the spleen, etc. This very incomplete and confused enumeration is sufficient for our purpose—viz., to show that we must speak, not of a centre, but of the synergic action of several centres, differently grouped according to the cases.^[80]

It is well known that the vaso-motor nerves of the head, the upper limbs, the lower limbs, the viscera, are furnished in part by the nerve-reticulations of the sympathetic system, in part by the rachidian nerves issuing from different parts of the spinal cord. Now, an experiment of Claude Bernard’s, made as far back as 1852, shows that the section of the great sympathetic in the neck produces on the same side an expansion of the vessels, and an increase in the temperature, nutrition, muscular tonicity, and sensibility. On the contrary, galvanism applied to the same nerve produces constriction of the vessels and the contrary phenomena to the preceding. Féré points out that the manifestations of the first case are, in general, those of the sthenic emotions, as those of the second are of the asthenic emotions.^[81]

Whatever we may think of this comparison, the incontestable and so often recorded characteristic of emotion—diffusion—shows us that it is everywhere; that, if we could see with our eyes the cerebral mechanism supporting it, we should be spectators of the co-ordinated work of the multiple centres; that, consequently, the hypothesis of a localisation, of a seat in the limited sense, is in no way justified.

2. It is needless to remind the reader that the majority of idioms make the heart the incarnation of affective life, and that the antithesis of reason and passion is, in current speech, that of the brain and the heart. This opinion is not entirely a prejudice, as contemporary physiologists have shown.

Why is the heart, an unconscious muscle, promoted to the position of an essential and central organ of the emotions and the passions? It is so in accordance with the well-known physiological law which makes us transfer our psychic states to the peripheral organ which communicates them to our consciousness. It feels the rebound of all the impulses which strike us; it reflects the most fugitive impressions; in the order of the sentiments, no manifestation takes place outside it, nothing escapes it; it vibrates incessantly, though in different manners.

Claude Bernard, and after him, Cyon, have undertaken to justify the popular expressions regarding the heart, to show that they are not mere metaphors, but the result of accurate observation, and that they can be translated into physiological language. I here summarise their principal remarks.

The heart, the centre of organic life, and the brain, the centre of animal life, the two culminating organs of the living machine, are in an incessant relation of action and reaction which shows itself in two principal states,—syncope and emotion; the first due to the momentary cessation of the cerebral functions through intermission in the arrival of the arterial blood; the second due to the transmission to the heart of a circulatory modification. There is always an initial impression which slightly arrests this organ (according toaccording to Claude Bernard), whence a passing paleness, then a reaction which the heart, by reason of its extreme sensibility, is the first to feel; for, as the brain is the most delicate of the organs of the animal life, the heart is the most sensitive of the vegetative vital organs.

When it is said that the heart is broken by grief, this expression corresponds to actual phenomena. The heart has been arrested by a sudden impression, whence, sometimes, syncope and nervous attacks. The heart’s being “big,” answers to a prolongation of the diastole, which causes a feeling of fulness and oppression in the præcordial region. The “palpitation” of the heart is not merely a poetic formula, but a physiological reality; the beats being rapid and without intensity. The facility with which the heart is emptied, the regularity of the circulation being kept up by slight pressure, corresponds to the “light” heart. Two hearts beat “in unison,” under the influence of the same impressions. In the “cold heart” the beats are slow and quiet, as if under the influence of cold; in the “warm” heart, the contrary is the case. When we tell a person that we love him “with all our heart,” this expression signifies, physiologically speaking, that his presence, or the recollection of him, awakens in us a nervous impression, which, transmitted to the heart by the pneumogastric nerve, causes in our heart a reaction of such a kind as to produce in the brain a sentiment or an emotion. In man, the brain, in order to express its feelings, is obliged to take the heart into its service.^[82]

Let us further recall the well-known observations of Mosso, who was able directly to study the circulation of the blood in the brain in three patients, in whom the cranium had been destroyed by various accidents. He ascertained that the mere fact of looking attentively at one of his patients, the entrance of a stranger, or any other occurrence of slight importance, immediately quickened the cerebral pulse. In one, a woman, the height of the pulsations suddenly increased, without apparent cause; she had just perceived in the room a death’s-head, which somewhat frightened her. The same thing took place with another patient when he heard the clock strike twelve; this was because he did not feel able to say his noon prayers. I do not dwell on his researches by means of the plethysmograph, which have special relation to intellectual work.

It will therefore be understood how popular opinion has come to look upon the heart as the seat, or the generator, of emotions. This is the instinctive expression of a quite correct view: the supreme importance to the affective life of the visceral action summed up in a fundamental organ.

II.

Since, for the moment, we are eliminating movements in order to confine our attention to the internal conditions of emotion, it is easy to see that these conditions reduce themselves to that which we designate by the name of internal, organic, vital sensations. This is not the place to enumerate the modifications of each in the case of each special emotion (for which the reader is referred to Part II.); the question, taken for the present in its generality, is put thus: Are the internal sensations reducible to a single and fundamental process? If the answer is in the affirmative, the internal conditions of emotion would find themselves simultaneously determined under their most general form. We can, at any rate, try.

The first difficulty consists in our not having a complete enumeration, on which all authors are agreed, of the internal sensations, as we have in the case of the special sensations. Beaunis gives a very detailed classification in eight groups; Kröner adopts a somewhat different one; both include pleasure, pain, and the emotions. Let us eliminate this last group (the affective manifestations) and confine ourselves to the vital sensations properly so called, connected with purely physiological needs, with the organs and functions indispensable to life: the different sensations of the alimentary canal (hunger, thirst, malaise, nausea, etc.); those of the respiratory apparatus (the need of fresh air, dyspnœa, asphyxia), of the circulatory apparatus, of the excretions and secretions; of the sexual organs in the normal state or in transitory phases (puberty, menstruation, pregnancy, menopause); the need of muscular movement, of rest, of sleep; the sensation of fatigue;—we have nearly all, if not all, the elements of cœnæsthesia, i.e., the consciousness of the body as living and acting.

Have these multiplied sensations a common cause? Are they different modes of one and the same process? Do they imply, at their origin, the same stimulus, the same kind of excitement, as all the varieties of visual sensations suppose luminous vibrations, and the varieties of auditive sensations, sonorous vibrations? Kröner maintains that, for all internal sensations, the initial excitation is of a chemical nature. “Every organic sensation is based on a chemical process, and arises according to the laws of diffusion and osmosis.”^[83] The author justifies his assertion by the enumeration of a large number of facts, for which I refer the reader to his book. Chemical action, according to him, either takes place under the gaseous form (a person passes from the open air into a room full of deleterious miasma) or under the liquid (alcohol, toxic substances in solution in the fluids of the organism and introduced into the circulatory current).

It is not very certain, pace Kröner, that all internal sensations are caused by chemical action, under one or other of the forms we have mentioned, and that their vague localisation is due to this cause alone, and not, as generally admitted, by their arising in organs incapable of movement. Thus tickling, giddiness, the muscular sensations (which Kröner and Beaunis include in this group) appear to depend on mechanical excitations rather than on chemical causes. At any rate, one cannot deny that the internal fundamental sensations—connected with nutrition and its immediate conditions, with fatigue and sleep, both of which result from a poisoning of the muscles and the nervous centres, with sexual life—are due to chemically caused excitations. This granted, we may go one step further in the track of James and Lange, and say that the emotions depend not only on physiological conditions, but still more intimately on the chemical action going on in the tissues and fluids of the organism.

In support of this extreme condition of the genesis of the emotions, we can only offer some fragmentary remarks, which, however, show how closely they depend on the variations of the intra-organic environment.

1. We have, in the first place, the group of exciting, tonic, depressing, toxic substances: wine and the various alcoholic beverages, haschisch, opium, coca, the aphrodisiacs, etc. Although they are artificial products, introduced from without, not engendered in and by the organism, we know how far they modify the interior environment, and consequently the temper, character, intensity, and direction of the passions.

2. But there are also the substances which the living body compounds or modifies for itself. It has been said that the organism is the receptacle and laboratory of poisons; in the state of emotion, the only one with which we are concerned at present, the function of this chemical process is manifested at every instant. We are always speaking of the weakening or the increase of the circulation of the blood; yet the emotional dispositions or modifications are connected, not only with variations of quantity, but also with those of quality in the blood (anæmia, aglobulia, malarial poisoning, etc.). The popular expression regarding the emotions which “curdle the blood” is not so ridiculous as it might seem. Anger, fear, fatigue are often accompanied by changes in the intimate constitution of the sanguinary fluid. We may incidentally note the ascertained relations between certain cardiac affections and affective dispositions: in aortic affections, anæmia, excitement, irritability; in cases of mitral insufficiency, congestion, and a taciturn and melancholy humour. We shall elsewhere have occasion to enumerate the facts which show the correlation of certain emotions with toxic changes in the saliva and the lacteal secretion. Perspiration may, in certain affective states, be coloured red, yellow, green, or blue, not to mention the varieties of odour, which are assuredly of chemical origin. Even apart from mental disease, the urinary secretion could furnish a long list of chemical changes (azoturia, oxaluria, phosphaturia) coinciding with variations of the affective order, such as apprehension, melancholy, irritability. In gouty and rheumatic patients, the modifications of temper, depending much more on general nutrition than on active suffering, have often been pointed out. We know the relations between the secretion of the gastric juice and pleasurable or painful states; dyspeptics have a well-established reputation for being neither cheerful nor comfortable to live with. Beaumont ascertained, in the case of his famous Canadian, that under the influence of anger or other very strong emotions, the lining of the stomach was irritated, became red, dry, and very sensitive, and an attack of indigestion was the result. The rutting time (that of sexual excitement) is, in many animals, accompanied by deep-seated chemical changes, showing themselves externally by modifications of colour and odour, and, internally, not limited to the sexual organs, but extending to the whole of the body. It is known that the flesh of game is uneatable during this period, and that many fish, at spawning-time, become poisonous. It should not be forgotten that, during the same period, the animal becomes vicious, violent, aggressive, and dangerous. It would be easy to develop this point further, even as regards man (puberty, gestation, lactation, menstruation).

3. It has long been observed that, in the great majority of cases, mental disease begins by affective disturbances and that the intellectual aberrations only make their appearance later. Much more recently, a doctrine has been propounded which tends to seek the primary cause of these affective disturbances in a self-intoxication—i.e., in “the disorders produced in the interior of the organism by the excessive formation or the morbid retention of normal poisons; in particular, by those originating in the digestive canal and the urine.” Nutritive troubles through acceleration, retardation, or perversion, are assigned as the most general cause. In support of this, we are referred to the relations between melancholia, hypochondria, a pessimistic disposition, with hyperchlorhydria of the stomach, and the good results of purgative medicines; the numerous mental modifications coinciding with organic chemical modifications—e.g., certain attacks of mania in arthritic subjects. “One characteristic of the mental state of diabetic patients is the way in which the fluctuations of the mental state correspond with those of the sugar, and the barometric (if one may so call it) influence of the composition of the urine on the moral disposition.” This liquid, in mania, loses, to a great extent, its toxic character, in consequence of the morbid retention of normal poisons which are no longer eliminated.^[84]

A long enumeration of facts bearing on this as yet insufficiently studied question would be here out of place. Besides, it could only be of real value if systematic—i.e., if under the heading of each emotion were grouped the physiological facts invariably accompanying it, and all the chemical modifications exclusively peculiar to it. We have only included the chemical conditions in our study, in order to penetrate as far as possible into the most general conditions of affective life, and show once more why it betrays the inmost constitution of the individual.

When treating of pleasure and pain, we remarked that they were too exclusively attributed to intensity of excitation (excessive, it was said, for pain; moderate, for pleasure), and that its quality was forgotten. Since we have to do with hypotheses as to the part played by chemical conditions in affective life, since they are the most general, and since pleasure and pain also have this character of generality, it may be permitted to hazard a conjecture. This would consist in admitting that pleasure arises either when excitement increases chemical activity in the organism, without producing toxines, or when this augmentation of activity brings about the disintegration of the normal poisons; and that pain arises either when excitement creates an environment appropriate to the formation of toxines, or when, directly and at once, it promotes their formation, either generally or locally. But I would not insist on a simple obiter dictum, for which I can offer no proof, thrown out merely as a suggestion with regard to a question not as yet fully examined.

We have spoken throughout of the chemical modifications as coinciding with emotional changes. Are they effects or causes, or both, according to circumstances? It is clear that this question is not new to us. It is the antithesis between the psychological and physiological theories of emotion, presenting itself under another aspect; there is no occasion for discussing it a second time.

Empiric period—Pre-Darwinian period of scientific research—Examination of Darwin’s three principles—Wundt and his explanatory formulas: Innervation directly modified, Association of analogous sensations, Relations of motion with sensory representations.

The movements of the eyes, mouth, face, the upper and lower limbs and trunk, and the modifications of the voice constitute the external expression of emotion which is principally reducible to muscular action. For the last half-century this subject has been studied in works so well known that it behoves us to be very brief. I shall confine myself to indicating the actual state of the question.

For some thousands of years this question remained in the stage of pure empiricism, or of so-called scientific speculations which had scarcely a better reputation than alchemy, astrology, or chiromancy. J. Müller, in the name of physiology, declared the expression of the emotions completely inexplicable. However, the researches were already beginning which were to prove him mistaken—those of Lavater with his rare talent of personal observation, and those of Charles Bell by a more objective method. After this, Duchenne, of Boulogne, went still further, substituting experiment for mere observation. It is well known that, in the case of an old man suffering from facial anæsthesia, he caused the contraction of an isolated muscle, by the aid of electricity, and thus produced certain modes of expression in the countenance. He concluded from this that the contraction of a single muscle often suffices to express a passion; and that every emotion has, so to speak, its accurate, precise, and unique note, produced by a unique local modification. Thus, the frontal is for him the muscle of attention, the upper orbicular of the lips the muscle of reflection, the pyramidal (inter-superciliary) expresses threats; the great zygomatic, laughter; the lesser zygomatic, weeping; the triangular muscle of the lips, disdain, etc. In spite of the somewhat artificial nature of the experiments, and the too sweeping character of the conclusions, this was a great step in advance.^[85]

At last appeared Darwin’s epoch-making work. Supported by the results of a long series of experiments on adults, children, lunatics, animals, members of the different human races, Darwin was the first to put, and to attempt to answer, the fundamental and only question—Why and how is such and such an emotion connected with such and such a movement and not with another? He stated the problem under its scientific form.^[86]

In Darwin’s works we find two elements: a detailed and complete description of each individual emotion or affective state—by which we shall profit later on—and the exposition of the general laws of expression, as reduced to three well-known principles. What remains of these three principles after the criticism to which they have been subjected? This is the only point we have, for the moment, to examine.

1. The principle of the association of serviceable habits remains the most firmly established. It consists in admitting that movements which are of service in satisfying a desire, or getting rid of a disagreeable sensation, become habitual, and continue to take place, even when their utility becomes nil, or at any rate doubtful. In other words, there are attitudes, gestures, movements, which can be directly explained, because they are nothing but emotions actualised, objectivised, or embodied, such as the movements of contact in tenderness, of aggression in anger, of erection and swelling in pride. But there are others, of which the explanation is less direct and obvious. How are the contraction of the eyebrows in perplexity, tears in sorrow, the showing of the teeth in anger, to be explained as serviceable to us? According to Darwin, these acts, formerly serviceable, have continued to exist as survivals. Here Darwin’s successors have rightly reproached him with not being enough of a psychologist, and have found a better explanation: the important fact is not the survival of serviceable movements, but the transference of a primitive mode of expression to an analogous emotion.

2. The principle of antithesis has been definitively abandoned; it is purely hypothetical, and explains nothing. According to Darwin, there is a primitive and general tendency to associate with feelings the contrary gestures to those expressing the opposite feeling. Léon Dumont has subjected this assertion to a very close and cogent criticism. Taking, one by one, the facts quoted by Darwin, which, besides, are not very numerous, he has shown that they may be quite otherwise explained.^[87]

3. The principle of the direct action of the nervous system cannot be placed in line with the other two, because it far surpasses them in generality, and, in relation to it, they are subordinate and not co-ordinate. Before Darwin, Spencer (Principles of Psychology, ii. §§ 495, 502) had stated an analogous principle, to which he reduced the expression of the emotions. He calls it the Law of Nervous Discharge. It may show itself in two forms—the diffused and the restricted. The former depends on the quantity or intensity of the emotion, and serves as its measure. It follows, in its propagation, an invariable course: it affects the muscles in an inverse ratio to their mass and to the weight of the parts they have to move. In man, it acts first on the delicate muscles of the voice and the small facial muscles; then it invades, in succession, the arms, the legs, the trunk. The movements of the tail in dogs and cats, of the ear in horses, and many analogous ones in other animals, are illustrations of this law. The restricted discharge depends on the quality or the nature of the emotion; it is due “to the relations established in the course of evolution between particular feelings and particular sets of muscles habitually brought into play for the satisfaction of them.”^[88] This scarcely seems to me to differ from Darwin’s principle of “useful habits.”

The Expression of the Emotions gave rise to other publications of the same kind, those of Piderit, Mantegazza, and Warner, who, in his Physical Expression (1885), has attempted a purely objective, and consequently extra-psychological study of the subject. But among all the attempts to trace back expression to its fundamental principles, and find a substitute for Darwin’s (already greatly shaken) theory, that of Wundt seems to me the best.^[89] Like his predecessor, he admits three principles (though different from Darwin’s) which can act simultaneously and concur in the production of an isolated movement.

1. The principle of direct modification of innervation—that is to say, that the intensity of the muscular and vasomotor movements depends on the intensity of the emotions; the movements which most escape the control of the will more especially depend on this principle. This is the equivalent to Darwin’s third principle, placed first, which is, in fact, its right position.

2. The principle of the association of analogous sensations consists in those dispositions of the mind which are analogous to certain sensory impressions, manifesting themselves in the same manner. At the outset, we have only pleasures, pains, and needs of the physical order, whose mode of expression is innate, and, so to speak, anatomical. Later on come the pleasures, pains, and desires of the moral order, which make use of the pre-existent modes of expression in order to show themselves outwardly. It is a language turned aside from its primary signification, which in the order of gestures is the equivalent of a metaphor. This principle explains much more easily than Darwin’s a number of apparently very perplexing modes of expression. If a man, when puzzled, scratches his head, coughs, rubs his eyes, it is because a slight malaise of physical origin and a slight embarrassment of psychical origin have a deep-seated analogy, betraying themselves by the same expressive movements. Wundt has well described the mimicry of the mouth in the tasting of sweet, acid, or bitter substances; as soon as an emotion arises which has some affinity with these gustatory sensations (sweet joy, bitter grief, sharp reproaches), the expression of the mouth, the nose, the face reappears. This is because, in both cases, the state of the feelings, the emotional tone are the same, the expressive movements identical. As Mantegazza has rightly said, there are such things as mimic synonyms.

3. The principle of the relation between movements and sensory representations lies in the fact that the muscular movements of expression relate to imaginary objects. Wundt considers as chiefly amenable to this principle the mimicry of the eyes, the arms, and the hands. We represent something large by raising the hand, a small object by lowering it; the future by a forward movement, the past by a backward one. It might be objected that these gestures indicate intellectual rather than affective states; but it is certain that many emotions have a mimicry addressed to absent objects. Gratiolet (1857) collected a tolerably large number. The indignant man, even if alone, clenches his fist against an absent adversary. We shut our eyes, or turn aside our face, to escape the sight of a disagreeable object; we do the same when disapproving of an opinion. When we approve, we incline the head forward, as if in contemplation. In negation, we turn the head to right and left, exactly as is done by children and animals, when an unattractive object is placed in front of the mouth. The expression of disdain, contempt, disgust, reproduces the physiognomy of a man rejecting nauseating food.

I am not quite sure that Wundt’s third principle is of the same importance as the other two, or that it cannot be reduced to a still simpler form. But the theory I have just summarised, with a few examples borrowed elsewhere, presents itself as the one most calculated to bring out the importance of the physiological factors, unduly neglected by the pioneers of the science.

All the work relating to this question, whatever may be its lacunæ at present, has demonstrated that the expression of the emotions is not an adventitious, purely external, extra-physiological fact, whose study is only incumbent, as science, on the physiologist, and, as art, on the physiognomist, but emotion itself objectivised, its inseparable embodiment. In my opinion, we have to distinguish two strata in the very numerous modes of muscular movement which express the emotions. One is primary, depending on the anatomical and physiological constitution; the other, secondary, depending on the psychological constitution. The relation between them is that which in every developed language exists between the primary and the derived sense of words. Analogy is the great artisan of intellectual language; its action is more restricted as regards emotional language. But when, to the emotion of the first hour, having already its fixed mode of expression, there succeeds a new emotion, which the consciousness, rightly or wrongly, has felt as analogous, the pre-established expressive mechanism has served a new purpose, like an old word whose meaning is extended and modified. In both cases the mind proceeds in the same way, obeying the guidance of one and the same unconscious law.