# Popular Science Monthly/Volume 4/March 1874/Physiology of the Passions I & II

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* PHYSIOLOGY OF THE PASSIONS.
By FERNAND PAPILLON.
TRANSLATED FROM THE FRENCH, By J. FITZGERALD, A. M.
IF there is to-day a fact demonstrated by reason reflexly contemplating itself no less than by attentive observation of the entire development of human knowledge, it is the close interdependence of all natural forces and operations—a solidarity so firmly knit that it is impossible to study any one point of detail without reference to the sum total of the phenomena. The sciences, long kept apart from one another, now all tend to come together, to fuse into one another, for the explication of facts. It is the exigencies of the science of man that, above all, have determined this irresistible attraction, this systematic confluence of branches of knowledge the most diverse toward one centre, where they attain their full value and their full significance. Man brings together within himself, as Buffon says, all the powers of Nature: he is the centre to which all things are referred—a world in miniature; no amount of analysis can come amiss, if we are to resolve the endless complexity of this so multiple being; and we need all the light we can get, in order to illumine the darkness that surrounds this mysterious creature. If, as Leibnitz thinks, one single monad—an imperceptible atom—is a mirror of the total beauty of the universe, how much more truly may this be said of that singular and diversified assemblage of monads, man! Surely it would ill become us to disparage the psychologist, whose study has been to get at a knowledge of man solely by observation of the phenomena of consciousness; or the physiologist, who has attempted to find an explication solely in organic phenomena. Both of these have, with much toil, broken the ground and prepared a field where investigation may henceforth bear fruit; but, precisely because the soil is now ready, it is to be hoped that the controversies and antagonisms of the past will give way to a good understanding, more conducive to a true knowledge of man's nature; and that inquiry, instead of diverging ​and so losing itself, shall be regulated and coordinated to the attainment of one end.
These reflections are addressed neither to those who imagine that psychology has done all its work already, nor to those who think that work never can be done; we submit them to those who, following attentively the double movement of physiology and of psychology, find that, at least, the progress made by each of these sciences is correlative with that made by the other, and inseparable from it. Philosophers, whose position and whose previous inquiries seemed very unlikely to invite them to the study of physical man, now devote themselves to this study with enlightened ardor. Experimenters, whose reputation and whose habits might appear very unapt to incline them toward the study of moral man, now pursue that study with conscientious diligence. The result is, a profounder and more precise science of the relations between the physical and the moral—a science that is full of revelations and surprises.
I.
The ancients had a theory with regard to the passions which, at bottom, differs not much from that countenanced in these later times, by experimental physiology and pathology. They erred with regard to the rôle of the humors and the physiological mechanism in the production of passional phenomena; but they had closely observed, and, with rare precision, defined the influence exerted by these on the viscera of the abdominal region. Their poetry and their medical writings are full of expressions which show how ancient is the knowledge of this relation between the soul's sentiments and the movements of heart, lungs, stomach, and liver. The ancients even went so far as to localize the passions in the viscera; and their theory on this subject is expressed in the aphorism, "Splene rident, felle irascunt, jecore amant, pulmone jactantur," where the spleen, the gall-bladder, the liver, and the lungs, are represented as the seat respectively of mirth, anger, love, and vainglory. The physiology of the passions, so far as it could be and was studied by the authors of ancient times, was, from the stand-point of description, a science of such exactitude that there is now little to be added to it. Still, they mistook the real seats of those states of the soul; and Descartes, in his famous work on the passions, was the first to hold that their seat is in the brain. He localized all passional states in that organ. "The soul," he says, "can suffer directly only through the brain;" and, in another place, "The ​soul does not receive impressions from all parts of the body, but only from the brain." This truth, which now seems so elementary, was nevertheless demonstrated only by the physiology of recent times. The greatest physiological theorist of the passions, Bichat, did not accept it, as we shall see from an exposition of his doctrine.
The first physiological character recognized in the passions, by Bichat, is intermittency. Whereas our thoughts may be continued—prolonged over a considerable period of time—and whereas a habit of making the same reflections and judgments strengthens and perfects them, the passions, on the other hand, have no persistence. With the exception of that pleasure and pain which we might denominate absolute, and which depend on direct nerve-excitation, it may be asserted that a habit of the same sentiments will soon blunt and weaken them. A prolonged sensation, be it pleasant or painful, at last gives neither pleasure nor pain. The perfumer, who is ever surrounded by an odorous atmosphere, does not enjoy the sweet scents. All that delights the eye or charms the ear becomes indifferent when the impression has lasted for some time. The same holds good for disagreeable sensations. "Happiness, therefore," says Bichat, "consists only in incontinuousness. Pleasure is but a comparative sentiment, that ceases to exist where you have uniformity between present and past sensations. Were the forms of all women cast in one mould, that mould were the grave of love."
This profound difference between thought and passion Bichat explains by the theory that the former is dependent on that side of our being which we call animal life, while the latter proceeds from the organic life. Every thing that has to do with intellectual operations, properly so called, has its seat in the brain, which is the centre of animal life. Every thing that has to do with the passional states has its seat in the viscera. The effect of passion of every kind is to produce some change, some alteration in the organic life, that is to say, in the organs of circulation, of respiration, and of nutrition. This fundamental difference between intelligence and passion, as regards the organs which seem to be their respective seats, has long been remarked by popular sagacity and incorporated into language. Such expressions as "a good head," "a fine-shaped head," have always been employed to express perfection of understanding; and "a good heart," "a tender heart," to express the perfection of sentiment. It has also been a current phrase to say that the blood "boils" with anger, or that indignation "moves" the bile, or that the heart "leaps" with joy. Our gestures accord with our words: thus, when we would in dumb show indicate some state having to do with memory, imagination, perception, or judgment, we bring the hand up to the head. But, when we would express love, joy, hate, disgust, we bring the hand up to the region of the heart or of the stomach.
A close observation of facts proves the correctness of the instincts ​that have given rise to these phrases and gestures. It is evident that anger accelerates the circulatory movement, and that joy has the same effect, while grief and fear produce the opposite results. Extreme emotions are sometimes followed by fatal syncope. Profound grief causes a difficulty of respiration. Sudden fright checks the secretion of bile. Independently of these palpable phenomena, the passions modify profoundly the nutritive processes, and give rise to disordered conditions, of a more or less grave nature. Here, again, language accords with physiology. To pine away with envy, or with remorse, to waste away with grief, are expressions that attest the influence of the passions on the organic life. Again, Bichat ingeniously notes the relation subsisting between the passions and the temperament. The individual whose lungs are highly developed, and whose circulatory system is specially vigorous, will naturally be of very impetuous disposition, choleric, passionate, and courageous. Where the biliary system predominates, enviousness and hate seem to be more habitual. The lymphatic temperament gives to the passions a quiet and indolent character. Thus every thing, according to Bichat, goes to show that the organic life is the terminus to which the passions tend, and the centre from which they start, and that the animal life only suffers from the rebound consecutively. If the focus of the animal life is the brain, then what is the focus of the organic life? What is the apparatus specially concerned in producing emotions and passional manifestations? Bichat holds that there is no one organ on which this office devolves exclusively, and he localizes the passions in what he calls the epigastric centre; that is to say, in the heart, the lungs, the liver, the gall-bladder, and the ganglionic nerve-system, distributed throughout these organs. Each of these is, according to him, the seat of a distinct passion, and the movements that are determined by this passion are perfectly involuntary.
Such is Bichat's doctrine of the passions; it is the ancient doctrine, only developed and elucidated, reasoned out with greater precision, and fortified with fresh proofs. It is correct in its analysis of the visceral disturbances produced by the passions, but erroneous in that it regards the viscera as their main-spring and origin. To Gall belongs the honor of having proved that the passions primarily affect the brain, and not the viscera. It was the experiments made by that great man which showed that the brain is the organ of sentiments no less than of ideas. His argument against Bichat's theory may be reduced to these fundamental observations: The heart and the diaphragm are only muscles, the stomach and the liver only secretory apparatus, the kidneys only an excretory apparatus, and the spleen only a sanguineous gland. Several of these organs may suffer lesion or be removed and still the passions remain; hence we cannot localize the passions in them. Gall, in the next place, examines all the parts of the nervous system outside of the brain, viz., the plexuses, the ganglia, the nerves, and the sensory ​apparatus, and shows that here too it is impossible to find the source of our propensities, instincts, affections, or passions. Finally, he examines the brain itself, and in it discovers the exclusive seat of all these activities. That the passions depend essentially on the brain is proved from the fact that any impairment of that viscus determines a perturbation of the passional no less than of the intellectual phenomena. When we see physicians of half a century ago, who were profoundly versed in the study of insanity—a Pinel or an Esquirol, for instance—hesitate about locating in the brain the immediate cause of dementia and the various forms of mania, we can appreciate the importance of the service done by Gall to the science of man, when he rigorously demonstrated the ill-understood functions of the brain, and proved the correctness of Descartes's doctrine of the passions.
The experiments of modern physiologists, those of Claude Bernard in particular, show that all sensations act primarily on the nerve-centres, through the nerves reaching from the periphery of the body to those centres. The excitation thus determined in the brain, or in the spinal cord, is then transferred to the nerve-filaments which extend to the viscera and members, and hence the latter are affected only secondarily. Of all the organs, the heart is the one which earliest and most profoundly experiences the influence of the sensitive excitations produced in the nerve-centres. So soon as any modification whatsoever is produced in the central nerve-substance, the nerves transmit this vibration to the heart, and at once the movements of the latter suffer a perturbation which is expressed in various ways. At one time the nervous action is sufficiently energetic to at once stop the working of the heart; and, as the blood is no longer discharged into the vessels, syncope (fainting) is the result, the skin assuming the pallor and lividness of death. Again, the reverse effect takes place, the beating of the heart being accelerated, instead of being stopped; in this case the blood is forced through the distended vessels to the brain, and there is over-excitation of that organ's activity. The heart is no more the seat of the sentiments than the hand is the seat of the will, but it is a reactive which is modified by the sentiments, with the utmost nicety and with infallible certainty. Not only does the heart betray, by the very disturbance of its normal rhythm, the nature of the initial brain-excitation, but it also produces throughout the whole organism disordered actions, the sum of which constitutes, as it were, the physical image, the palpable externals of passion. But it produces this disordered action only by reacting on the brain, which is the organ of all the demonstrations and of all the movements of the nerves, and consequently of the muscles. Thus it is that the heart and the brain, the blood-system and the nerve-system, conspire in the production of passional phenomena, by a series of alternate actions and reactions.
Such, are at least, the chief points of Claude Bernard's doctrine, as set forth at a famous Sorbonne conférence, in 1864. At that period the ​nature of the nerve-connections of the heart with the brain were as yet unknown, and a Russian physiologist, E. Cyon, has, for some years past, labored successfully to fill up this gap. The heart is provided with a number of little self-acting nerve-ganglia, without relations to the brain, from which spring, under the influence of the blood, a certain number of motor impulsions. These ganglia govern the usual normal action of the cardiac apparatus; but the rhythm and the force of the beatings are every instant modified by excitations having their origin in the brain. The latter organ sends out to the ganglia of the heart two sets of nerves—the pneumogastric, or retardator, and the accelerator nerves. Excitation of the former diminishes the frequency and augments the force of the heart's movements. The accelerator nerves produce the opposite result, increasing the number and lessening the force of the heart's contractions. These two sets of nerves accommodate the activity of the heart to that of the rest of the organism, and hold it in equilibrium with the continual oscillations of the various functions of body and soul. Besides these filaments, extending from the brain to the heart, there are others from the heart to the brain, which M. Cyon calls depressors. The office of these nerves is to notify the brain, and consequently the soul, of the changes occurring in the rhythm and energy of the cardiac contractions. Thus, in virtue of the pneumogastric and the accelerator nerves, the heart is an organ whereon is reflected, immediately and with precision, every passional state, with its nicest shades of distinction. And, on the other hand, in virtue of the depressor-nerves, our consciousness notes the infinitely-diverse oscillations of the heart's beatings attendant on passional states. The mechanism of the heart's motions under passion depends on these two inverse nerve-currents.
Every agreeable or joyous emotion of the soul excites the accelerator nerves of the heart, and causes that organ to beat with great rapidity, lessening at the same time the force of its contractions. The phrases, the heart leaps with joy, or flutters with joy, admirably characterize this action of the accelerator nerves. The facility with which the heart drives the blood into the arteries, under such circumstances, produces that feeling of comfort and pleasure which is expressed by the words, a light heart. On the other hand, all sad or painful feelings act chiefly on the retardator fibres of the pneumogastric nerves. Emotions of this description diminish the rapidity of the heart's beatings, and so increase the amount of blood discharged from that organ at each diastole; hence the contractions by which it drives the blood into the vessels are laborious and protracted. These contractions, attended as they are with pain, give rise to an ensemble of sensations, expressed in common language by such phrases as oppression of the heart, the heart is agonized, etc. That other phrase, the heart is ready to burst, expresses, with great exactitude, the sensation of stricture one feels when suffering from pent-up anguish. The news of some ​painful loss, when suddenly conveyed, oftentimes produces wild, irregular contractions, owing to a paralysis of the retardator nerves, and it is not rare to find this disordered excitation followed by a total stoppage of the heart's action, and syncope. Hence, says Claude Bernard, when we have to communicate to a person some heart-breaking piece of intelligence, we must use great precaution. The intensity of the effects produced on the heart by the soul's emotions depends, above all, on the excitability of the nerves connecting heart and brain. The greater the excitability of these nerves, the more pronounced are the heart's motions, and the finer, too, and the more delicate are the consecutive impressions. It is because the nerves of women and children are more excitable than those of men, that their hearts also are more profoundly affected by the emotions; or, in common language, their hearts are more tender, more sensitive.
While the heart seems to be more directly under the influence of the feelings, the lungs appear to have some connection with thought. When absorbed in some profound meditation, or when listening to some orator whose discourse rivets our attention, we suspend the respiratory movements. Darwin offers an ingenious explanation of this phenomenon, attributing it to the habit we have contracted of not breathing when we are listening attentively, so as not to disturb by the sound of the breath the silence necessary for catching every syllable.
From the fact that the real affections of the soul, and consequently of the brain, are always accompanied by disturbance of the respiratory and circulatory functions, we may conclude that the heart and the arterial tension are the true index of the passional states. Hence it is that the actor, when he would prove that some perilous situation inspires him with no fears, seizes the hand of the one he seeks to reassure or to convince, and places it over his own heart, in order to show that the beatings of that organ keep up their usual rhythm. Hence, too, it is that we must not regard outcries and gestures as positive indices of passion. When you see a woman weeping and agitated on hearing some painful news, you have only to feel her pulse; if that is normal, you may pronounce the emotion simulated. On the other hand, if you see a woman whose distress is manifested by no outward signs, but whose heart beats with unwonted irregularity, you may be sure that she feigns a calm that is not in her soul. There is yet another mode of ascertaining, and even of measuring accurately, the strength of emotions. This we may do by applying either to the pulse or to the heart one of those delicate apparatus invented by M. Marey, which trace on a sheet of blackened paper curves of greater or less sinuosity, representing the number, the force, and the form of the beats of the pulse, or the contractions of the heart. Just as these apparatus give us tracings which at once indicate the nature of the heart's motions in various diseases, for instance, fever, typhus, or ​pneumonia, they might in like manner give us graphic representations of its motions under the influence of the various passions, such as love, fear, grief, joy, anger, etc. Indeed, each of these states of the soul produces, in the order of the heart's beatings, a modification so peculiar and characteristic that we may regard each of the passions as having a curve of its own. M. Cyon, who has recently suggested this ingenious idea of applying graphic apparatus to the physiology of the passions, gives some illustrations of the bearings such experiments might have. Among the heirs gathered round the bed of a dying man there is one whose grief causes his heart to beat slowly but violently. In some of the others, who impatiently await the end, the heart beats quickly but feebly. The graphic apparatus, which describes, with marvelous precision, the rhythm of cardiac contractions, and which is called the cardiograph, could in this case exhibit the real feelings of the heirs. This is not at all an exaggeration, and we have no doubt that an instrument of great sensibility could be got to note the differences here referred to. Perhaps the case would be different under circumstances of greater complexity. The modifications of the heart's beating intervene in a twofold manner, in the determination of our inclinations and in the acts which proceed from them, either by producing sudden changes in the quantity of blood diffused through the nerve-centres, or by giving us agreeable or painful sensations through the depressor nerves. Now, a sudden afflux of blood to the brain, and extremely painful sensations, may produce, in a man not suffering from any mental disease, the craziest notions, and may betray him into the commission of the most serious offenses. Suppose a man commits a crime under circumstances but ill understood; the question arises, Was he moved to the act unconsciously and by physiological causes, or did he do it designedly and after calm reflection? M. Cyon thinks he can resolve this problem as follows: The soul possesses the faculty of experiencing, on the recollection of a past act, emotions of a like kind with those it experienced at the moment of its commission. The detailed history of a crime must produce in the accused who listens to it—supposing that he had committed the crime knowingly—emotions of this kind, as also the cardiac motions necessarily correlative to them. Hence the judge may, by means of the cardiograph, inform himself as to the presence or absence of these motions, and so decide whether the accused has or has not a recollection of the crime, i. e., has committed the crime whether with or without consciousness. This instance is rather ingenious than plausible, rather theoretic than practical. Of course, an individual who has committed a crime in a state of delirium cannot, on hearing the history of that crime, experience the same emotions, nor consequently the same modifications of the heart's movement, as he would if he had committed it with a full knowledge of what he was doing; still, it would be as hard for him in the one case as in the other, to maintain an absolute sang-froid. A man who is ​accused of having committed a crime, and who knows that he has committed it, is alarmed at the sight of the judge who questions him, and at the thought of the accusation which stands against him, even though the crime was committed in a moment of delirium. On the other hand, it may easily happen that a hardened malefactor, who has committed a crime with full deliberation, will be so far master of himself as to feel but insignificant emotion when the circumstances of his crime are brought up before him. Yet this idea of M. Cyon's merits the attention of psychological physiologists, and we may venture to hope that the day will come when treatises on psychology will conclude their descriptions of passional states with graphic tracings showing the rhythm of heart-contractions which answers to each passion. These tracings will be trustworthy and precise, for, if the will be mistress of movements and demonstrations that appear at the surface, it has but very little power over viscera that are concealed, like the heart, and these are truthful witnesses, ever at hand to rectify lying testimony.
II.
But we must bear in mind that muscles which are subject to the will are not always employed to dissemble passion, but that very often, by their almost automatic attitude, they betray the real state of the feelings. In vain would a man in a furious passion strive to stand still. All his members are agitated with violent movements. Astonishment produces a relaxation of the muscles, and hence the French phrase, les bras tombent (the arms fall), to denote the effects of this emotion. Fear causes one's legs to fail him; one is said to he petrified by fear. But there are none of the muscles that are so influenced, so modified by the passions, as those of the face. The physiognomy is indeed a betrayer of the soul's inner states. "When the soul is agitated," says Buffon, "the face becomes a living picture, wherein the passions are given with equal delicacy and force; where every movement of the soul is expressed by a dash of the pencil, and each act by a character, the rapid, living impress of which outstrips the will, thus unveiling and manifesting, by passionate signs, our most secret emotions."
It seems impossible to subject to physiological analysis appearances so complex, so varied, and so fickle. And yet an accomplished experimenter has recently succeeded in partially ordering this chaos, and in precisely determining the muscular mechanism of the human physiognomy as related to the various passions. Having first ascertained, by minute dissections, the position and separate function of the numerous muscles situate between the skin and the facial bones, and having learned how the nerve-filaments of the seventh pair (the facial nerves) are distributed through these muscles and animate them, M. Duchenne, of Boulogne, has determined, by means of the electric current, or of ​various excitants, the contraction of each particular one of these little muscles. Again, by observing those ready-made experiments which we call diseases, he learned what takes place when some of these muscles contract while others are inactive. In this way he has been enabled to see, most clearly, that the contraction of each muscle of the face determines a certain invariable expression; that is to say, that each passion seems to have at its command a facial muscle which contracts so soon as the soul is moved by this passion. M. Duchenne discourses as follows about the muscle of suffering (souffrance), as he calls the muscle whose contraction indicates pain. "From the very outset I had observed that the partial movement of one of the motor muscles of the eyebrow always produced a complete expression in the human face. For instance, there is one muscle which expresses pain—the superciliary muscle. On causing this to contract by electricity, not only did the eyebrow assume the form expressive of pain, but the other parts and features of the countenance, particularly the mouth and the naso-labial line, seemed also to undergo a profound modification, so as to harmonize with the eyebrow, and, like it, to give expression to this painful state of the soul." So, then, other muscles appear to share with the superciliary in the expression of suffering. M. Duchenne, however, believes that he is authorized by his experiments in holding that the muscular region of the face directly modified by a single passion is very circumscribed. But this modified region acts by a sort of sympathy on the adjacent regions precisely as one color modifies the tint of the colors all around it; and, just as, in the latter case, there is caused an optical illusion, the result of what Chevreul calls the simultaneous contrast of colors, so with the muscular movements of the face there is produced a kind of mirage which modifies, complicates, and seems to dilate a movement whose real sphere is very restricted. However this may be, M. Duchenne has succeeded in reproducing, by contractions called forth in a certain number of the facial muscles, nearly all those expressions which answer to the inner states of the soul, and he has thus been enabled to assign to each muscle a psychological in addition to its physiological name. Thus, the frontal muscle is the muscle of attention, surprise, wonder, and alarm, and each of these emotions excites it in a different way. The great zygomatic and the inferior orbicular muscles are the muscles of joy, while the pyramidal muscle of the nose is the muscle of aggression, and so on. In general, the muscles of the eye are adapted to expressions of the higher order, and those of the mouth to expressions of a more gross and material kind. The purely self-satisfied and sensual smile calls into play only the zygomatic muscle. It is the contraction of the inferior orbicular that gives to the expression of contentment and pleasure a character of good-nature and benevolence. Besides the primary expressions resulting directly from the play of one muscle, M. Duchenne finds that several ​passional states of the physiognomy may be resolved into a number of simple movements.
And, just as he produces simple passional expressions by artificial means, so, too, he effects the synthesis of the complex expressions. Attention, which is produced by the contraction of the frontal muscle, and Joy, which is due to the conjoint activity of the great zygomatic and the inferior orbicular, are primary expressions. Whenever we determine simultaneously on one face the contraction of these two muscles, we get the physiognomy of a person who has a lively impression of some pleasing and unexpected news. If, together with these muscles, we excite that which serves to express lechery—i. e., the transverse nasal muscle—we get the type of attention directed toward some lascivious object. If we associate the lines indicating pleasure with those denoting pain, we recognize at once the melancholy smile. When we combine the smile (by contracting the great zygomatic) with gentle grief (by contracting the minor zygomatic), or, better still, with a slight contraction of the muscle of suffering—the superciliary—we have an admirable and touching expression of pity and compassion.
These fine physiological dissections, and the masterly syntheses they suggested to M. Duchenne, are nearly in full accord, as concerns their results, with the most ancient observations of empiricism, with the intuitions of painters and sculptors, as also with the teaching of psychologists and moralists. Results of this kind add nothing to our knowledge of the body or of the mind, but they will, perhaps, be of service to artists who desire to be exact in the anatomical reproduction of the passional movements of the physiognomy. No doubt the genius of superior artists is a sure and potent instinct, which leads them to follow rules they know not; and it is probable that neither Raffaelle, nor Correggio, nor Titian, would have been a greater painter, had he known, as modern physicists do, the laws of harmony and the simultaneous contrast of colors. Nevertheless, this sure and potent instinct, the germ of which exists in the élite of the artist-world, may be to some extent acquired by laborious study, and hence the conscientious artist will understand all the advantage to be derived from a science which, by giving him precise and certain directions, will save him much preliminary labor and much fruitless experiment.
Why is one special muscle of the face affected by pain, another by fear, and a third by anger? In short, why is every passion interpreted in the physiognomy by regular, determinate movements, just as the rhythm of the heart is modified? To give the question a more general form, is there a logical relation between gesture and emotion? This is a difficult question, recently put by Mr. Darwin, and which he strives to answer in accordance with his usual doctrines. For him, instincts are habits originally acquired purposely, voluntarily, and afterward fixed in the race by heredity. The instinctive movements of the physiognomy, considered as passional ​expressions, have the same origin. Thus, the habit of praying with the hands joined palm to palm comes, according to him, from the fact that in past times captives testified their entire submission by holding up their hands to be bound by the victor. The captive assumed the kneeling posture, in order to make this operation easier. Thus, the gesture and the attitude, which are now the instinctive expression of adoration, of devotion, would be merely vestiges of the savage usages of primitive man. When we are angry with a person, we involuntarily close our fists, so that they may be ready for use, even when we have no intention of striking the one who has angered us. If, under the action of similar feelings, the lips contract so as to show the teeth, as though we were preparing to bite, the reason is, says Darwin, that we are descended from animals who used their teeth as weapons of offense. Why do the eyebrows assume an oblique position when a person is suffering pain? For this reason: when children cry from hunger or from pain, the act of crying profoundly modifies the circulation; the blood flows to the head, and particularly to the eyes, and this produces an unpleasant sensation. The muscles around the eyes then contract so as to protect them, and this action has become, under the influence of selection and heredity, an instinctive habit.
Most of Mr. Darwin's ingenious explanations thus tend to refer movements of the physiognomy, that are now involuntary and instinctive, to movements that once were voluntary and intentional. Many of these explanations seem plausible, but it is nevertheless true that the physiognomy betrays the emotions and passions by means of signs entirely independent of the will. That some of the muscular movements of the face arose in the manner described by Darwin we might admit, but still we cannot see how that accomplished naturalist can reduce under his fundamental hypothesis those complex movements which are expressed by laughter, lachrymal secretion, blushing, pallor, turgescence or flaccidity of the flesh, and the flashing and dimming of the eyes. All these phenomena are entirely independent of the will, nor can they be explained on the theory put forward by Darwin to account for the eyebrow contracting under the influence of painful emotions, or for the lips contracting in anger. Therefore, we are forced to the conclusion that the agitation of the cephalic centres, produced by the passions, calls forth, in virtue of the anatomical relations of those centres with the facial nerves and muscles, reflex phenomena that never were under the control of the will. The habit of seeing such and such an expression associated with such and such a passion leads us to judge of the one by the other; but yet the habit is not the efficient cause of the expression.
There still remains to be considered one more series of physiological phenomena which bear the impress of passion, viz., vocal phenomena. The inflections of the voice, as related to the passions, are as varied as the expressions of the physiognomy. Each passion has its ​own language, its own tones, its own note, just as it has its own nerve and its own muscle. Physiological analysis, however, is far more difficult here than in the case of the physiognomy. How shall we analyze the complex mechanisms that cause the lungs and the larynx to produce the various sounds of moaning, crying, groaning, sobbing, and sighing? We are acquainted with the ensemble of muscular functions which give rise to these different expressions of the soul's states, but why does laughter express gayety, and sighing express sadness? We cannot tell.
To sum up: a profound disturbance of the circulatory and respiratory acts; a more or less violent agitation of the members; changes of the attitude of the body; diversified movements in the physiognomy; infinitely-varied inflections and modulations of the voice—all these phenomena are the consequence of what takes place in the brain when that organ receives impressions of such a nature as to agitate it.
Hence we see that the main-spring of passion is the sense-impression. But what is this impression? In order to answer this question, let us analyze some passional state. We shall there find four principal elements: a more or less distinct initial sensation of pleasure or pain; voluntary or involuntary movements, more or less pronounced; and, finally, a recurrent sensation consecutive to these movements. It is clear that if there were no sensation there would be no passion. On the other hand, if the sensation were but a motion, we might say that passion consists of a series of motions originating in the agitation of the sensorium produced by the internal or external causes of emotion; but, then, we never could understand why this agitation, being purely vibratory, should affect us at one time agreeably, at another painfully, or why it should act in so many different modes. Hence the power of discerning, immediately, in the sensorial perception, differences that have no mechanical equivalent, cannot be explained on mechanical grounds, and it is absolutely necessary to recognize here a psychic faculty, whose function it is to ascertain and to conceive the causes of emotions, and to regulate, according to a certain harmony, the consecutive physiological movements. Passion, therefore, resides in a something that is neither the brain, nor the nerves, nor the muscles; a something which perceives, and joys, and suffers, and which moves the entire body in unison with its own feelings. Now, this conscious faculty, this faculty of perceiving causes in no wise mechanical, is the soul. The more deeply we study the physiology of the passions, the more are we convinced that the agitation of the nervous and motor energies is but the external manifestation of deeper causes, which we denominate psychic. So, too, the more we study into matter, the better we see that it is only an external form, a vesture that clothes the activity of an invisible principle. Thus does Science ever lead us back to that eternal and mysterious thing, force, and, beyond force, to spirit.—Revue des Deux Mondes.