Popular Science Monthly/Volume 1/July 1872/The Physiology of Emotion
|THE PHYSIOLOGY OF EMOTION.|
LECTURER ON PSYCHOLOGY AT ST. GEORGE'S HOSPITAL.
THE object of this paper is, to examine the physical accompaniments of mental action, and, chiefly, to discuss the nature of the feelings or emotions which accompany the various conditions of body and mind; in fact, to lay down the theory that feeling (or emotion, which is another name for high and complex feeling) is the state which accompanies the excitation of a nerve centre or centres, being pleasant or painful according to the condition of the centre, or the intensity of the excitation.
Supposing this view to be correct, there is no need to allot one place in the brain to the intellectual and another to the emotional portion of the mind, neither can we discuss them apart. The intellectual or idea function, the thinking and working function of the mind, may be supposed to depend on the intercommunication of the nerve cells or centres of the entire hemispheres, carried on by means of the nerve-fibres, this interaction being accompanied by a feeling or emotion peculiar to the centres acting, but which varies according to their physical state at the moment of excitation, or that produced by the excitation itself.
That the cells, which in their aggregation make up what we call nerve-centres, vary immensely in their endowments and qualities, is a fact which probably few will dispute. We have centres of vision, centres of hearing, centres of taste and smell: the nerve-cells which form the intellectual centres of one who comes of a long line of educated and cultivated forefathers will differ from those of a descendant of Bushmen, even before they have been submitted to the influence of education. But, besides the special quality or endowment which each cell possesses, that quality which constitutes one a cell and centre of vision, as distinguished from another which is a centre of hearing, there is in each a varying state or condition on which depends its efficiency, its power of perceiving more or less accurately that which is presented to it, or of communicating with other centres of idea or motion. This condition will be influenced by a number of circumstances—by due nutrition, by heat or cold, rest or fatigue; but, according to it will be the efficiency or non-efficiency of the cell-function: by it, moreover, will be regulated, as I conceive, the pleasure or pain experienced when the cells are called into action. When the condition is sound and healthy, the function of the cells will be duly performed, and, in the due performance, pleasure, not pain, will be experienced. In other words, the supply of nerve-force being ample, the cells will energize pleasantly: when the nerve-force is insufficiently produced, or by action is exhausted, the energizing will be attended with proportionate pain.
It may be a question whether "nerve-force" is the best term to apply to the condition I have spoken of. It is one which opens up the many controversies which exist, and have existed, as to. the nature of force, the relations of the various physical forces, and of these to the forces which we see at work in living animals. While, on the one hand, some shrink away from the very name of force, and will none of it, as a metaphysical entity to be relegated to the schoolmen along with that other metaphysical entity, the "mind" itself, on the other, it is to be feared that men have imagined that the study of mental phenomena has, at length, attained to the rank of the exact sciences, because they have placed nerve-force in the same category and correlated group as light, heat, gravity, and electricity. "Animal combustion," says Mr. Bain, "maintains nervous power, or a certain flow of the influence circulating through the nerves, which circulation of influence, besides reacting on the other animal processes, muscular, glandular, etc., has, for its distinguishing: concomitant, the mind. The extension of the correlation of force to mind, if at all competent, must be made through the nerve-force, a genuine member of the correlated group." It may be interesting to see in what way another distinguished philosopher connects the forces of purely physical phenomena with those of life and animal movement. In his work on Heat (p. 499), Prof. Tyndall writes: "The grand point, permanent throughout all these considerations, is that nothing is created. We can make no movement which is not accounted for by the contemporaneous extinction of some other movement. And, how complicated soever the motions of animals may be, whatever may be the change which the molecules of our food undergo within our bodies, the whole energy of animal life consists in the falling of the atoms of carbon and hydrogen and nitrogen from the high level which they occupy in the food to the low level which they occupy when they quit the body. But what has enabled the carbon and the hydrogen to fall? What first raised them to the level which rendered the fall possible? We have already learned that it is the sun. It is at his cost that animal heat is produced and animal motion accomplished."
When I speak of there being in each nerve cell or centre a condition, varying within certain limits, according to which it is capable of energizing more or less readily and pleasantly, I am far from intending to convey a not ion of any metaphysical entity, even if I use the term "nerve-force." It is not possible to separate this force in kind from that which is the special property of the cell. Each cell, as it lives its life in our bodily organization, as it grows to maturity, and fades in its decay, separates and selects from the blood, by a molecular metamorphosis, that which it requires for its function as an idea-cell, a hearing, or a sight cell, but it separates it in varying quantity and quality, and, having separated it, parts with it again, according to the demands made upon it. So this force, specialized by the various portions of the human brain, exists in every cell and centre, in greater or less degree, and upon the condition of its existence depends, it would seem, the pleasure or pain experienced when the part is called upon to act.
A cell, when it sets in action other cells, or other organs of the body, appears to deprive itself of this force, and in time to become exhausted, so that rest and repose are necessary for its renewal. If it be too metaphysical to talk of the conversion of bodily heat into force, and of force into muscular motion, it is, nevertheless, a fact of observation that a nerve-centre becomes exhausted by over-excitation and over-action, and, being exhausted, becomes incapable of energizing till its power or force is renewed by rest or food. In the following observations I shall try to illustrate the theory that a nerve-cell is called into action by stimulation applied to it from without, and that, according to its special quality, it will then energize and act upon other cells or structures. The amount of action, and the feeling attending it, depend on the condition in which it is at the time. And this condition will vary in proportion to its rest, nutrition, and heat, and also in proportion to the strength of the stimulation and the length of time during which it is carried on.
The first question is, By what method are we to gain any information upon these points? Absolute proof of what I have asserted is not to be expected; were it forthcoming, we should have learned it long ago. We shall have to apply the methods of observation and experiment, and, of these, observation will aid us most. We can observe the phenomena of Feeling in infants from the commencement of life, in children, in adults, in the aged. From mere sensations we can trace the dawn of what are called Emotions, or, to use an older terminology, Passions. We can observe them also in the lower animals, and in the varieties, so to speak, of man—in the savage, the insane, the idiot. And, in observing the feelings, we are compelled also to observe the outcome of them in the shape of bodily and facial motion, which is often the only evidence of their existence. Also, we shall observe the same individual under the various conditions of hunger and repletion, of sleep or want of sleep, of cold or heat, of health or disease. And we shall see how all the phenomena, which our inductive observation can collect, agree or disagree with the laws laid down by those who have by experiment investigated the physiology of the nervous system. From one method—dissection of the actual brain—we shall not learn much. When the action is over and the force departed, the actual structure teaches us little about the working. The greatest discoveries have been made by experimenting on living animals.
If we observe the life of an infant, we find it spent chiefly in sleeping, its short waking-time being principally occupied in feeding, in accumulating the material for its structural and functional growth. Its acts consist of sucking, crying, and kicking, and of using to some extent its eyes and ears. It does not at first see any thing as an object; it merely undergoes the subjective sensation of light; its retina and sensory ganglia are stimulated by light; and, if the light be too bright and the stimulation too strong, it testifies the pain experienced, by contracting the eyelids and crying. On the other hand, it is pleased by being brought before a lighted candle or other gently-stimulating light. The acts very soon indicate pleasure or the reverse, and we know whether the child is pleased or not long before it can tell us. It is pained by cold or hunger or bodily suffering, by a too vivid light, by a loud or harsh sound, as it shows by crying, by movement of its body and facial muscles. Its pleasure is denoted by laughing, kicking, and corresponding movement and expression of face. It derives pleasure also from excitation of its centres of motion, from being tossed, dandled, and rocked, while rough and violent movements cause no less pain and discomfort. We see, then, in such a child, manifestations of a very considerable amount of feeling—feeling which is at this stage entirely bodily, or at the most sensory, arising from the exercise of the senses.
A little later, and we find that the child can discriminate between the voice and face of its mother or nurse and those of a stranger, deriving pleasure from the one and pain from the other, and evincing memory. It remembers what it sees and hears, and what it experiences; and as the original events were pleasant or painful, so are the recollections of them, as we learn from the manifestations it exhibits. We know nothing of a child's inner life except from these manifestations, for it tells us nothing. All we learn is from its facta, its acts; it does not yet talk, and, when it commences, its talk is only of concrete objects. It has no abstract terms or generalizations in its vocabulary.
If we trace the development of this child, we see how its pleasures and pains, which at first are entirely corporeal, merge by barely perceptible degrees into mental feelings, and how these expand from mere feelings into the emotions of adult life. Its feeling is being perpetually evoked by every thing that it sees and hears. By turns it displays anger, fear, pain, or delight, and the feeling called up by one object is only to be allayed by the substitution of another, which, stimulating another centre, will by such stimulation rouse another feeling. If we look at a boy of three years, healthy and strong, whose sleep and appetite are good, and whose nerve-centres are full of force, we see that his whole waking-time is employed in the keen enjoyment of spending his nerve-force in incessant motion and play. There is no work in him: his life is all active amusement, emotive movement. He exhibits rage, terror, jealousy, wonder, vanity, love, the desire for action; and these emotions are fully developed and unmistakably exhibited. Here, then, we have the emotional part of our nature apparently full-grown, while the intellectual is yet in its early infancy. We know that it is in vain to reason with such a child: we control and manage him. These feelings are all expansions of the self-feeling which is plainly seen to be the feeling of the entire bodily organization. The child at first derives pleasure or pain from that which affects its bodily sensations, from the light or the color which pleases its sense of sight, from the song which gratifies its ear, from the warmth which is grateful to its skin, from the food which satisfies its stomach; and it extends its likings to those persons or things which minister to its comfort, its dislike to such as cause it discomfort, and so it displays its love, its hate and fear. These feelings are all reflected upon and through the medium of the body in facial and other movements. As the nerve-centres in which this self-feeling resides are roused and excited, so, according to the centre stimulated and according to the degree of stimulation, we have a corresponding series of movements as the result. There is a direct outcome of action, a direct conversion of force into motion, so to speak; without this we should not know that such stimulation had taken place.
How motion immediately follows the application of a stimulus to the centres is especially shown at this time of life. There is no deliberation, no delay; the action, the demonstration of joy, or sorrow, or resentment, or approval, is instantaneous. The motor centres respond to the stimulus as immediately as the pupil responds to the light, and the reflex action of the one is as purely physical as that of the other. A child at this age possesses ideas formed from the memories of sensations and their associations, but its ideas are few, and it does not link them into chains of reasoning. Its intellectual processes are scanty, and so it comes to pass that the excitants of its nerve-centres are for the most part external events and sights, which at once result in bodily or facial demonstration rather than in internal mental action.
If mankind had stopped at the level of a child, if the higher and more complex emotions did not exist, it is not likely that various seats of emotion would have been mapped out in the brain. Emotion in children and animals is manifestly so much more a bodily excitation, the bodily movement follows so immediately as the result, that we do not confine it to a mental phenomenon as we do the higher emotions of man. But physiologically there seems to be no line of demarcation between simple feelings and the highest emotions. Before we examine the adult as we see him in the educated and refined inhabitant of the cities of Europe, we may pause and consider the various intermediate stages which carry on the succession from the child upward. There is the savage of all grades of savagery, from the Earthman to the stoical brave of North America who scorns to exhibit emotion of any kind. Many travellers have told us how like the tribes of Africa are to children, how they display emotion in a similar manner, how they instantaneously respond to a stimulus, whether it call forth joy, anger, or grief. Then there is the uneducated and unenlightened pauper of many an agricultural district of our own land, and there is the idiot, and the insane, whose self-feeling is predominant, whose whole life is centred in self, as much as is the child's. If after these we consider adult and educated man, we shall see that his sensations, feelings, and emotions, each mental state, in fact, which is called up in his brain, may be, and for the most part are, attended with muscular movement voluntary or involuntary, indicating the pleasure or pain which accompanies the mental stimulation. The amount of movement will often be the measure of the amount of force extricated and emitted from the centre on the application of a stimulus.
The first thing we notice is that most of the emotions of man are the same in kind as those of children, or even the inferior animals, the same in kind, though varying in complexity and specialty, according to the infinite variety of the acquirements of the human brain. The emotion of admiration, awe, and wonder, which fills our breast on seeing some marvellous spectacle or hearing some great news, what is it but the wonder which we see depicted in the animal when it sees for the first time something entirely novel and strange? I once saw a leveret meet face to face a young dog in a covert. Probably neither had previously encountered such an object. They stood for a moment transfixed with surprise; this, changing in the hare to fear, caused it to turn and fly; the dog, not quite so timorous, pursued, his wonder being converted, by the leveret's flight, into the emotion of pursuit. The animal's emotions we recognize by its motions; we could not otherwise assert that it experienced emotions at all. Its brain, when stimulated, at once converts its force into motion. And, if we strictly analyze the feelings and emotions of man, we shall find that here also action or motion of some kind is almost invariably the concomitant of emotion—at any rate, when this is at all intense, or, as we rightly say, powerful. With regard to many of our feelings and emotions, this is at once apparent. If some sudden disaster occurs to a man, his countenance, probably his limbs, will denote his terror, grief, or anger. He is said to be devoid of feeling, if this be not the case. His mode of speech, his tone of voice, is affected by it, and he may be led into immediate and violent action, so involuntary that it may almost be called automatic. On the other hand, pleasant sights and news will produce corresponding traits in countenance and movements of limbs. The latter will be less marked than those set in motion by pain or grief, inasmuch as a pleasant stimulus will set up less violent action than one that is painful.
When we look at the simple emotions and feelings of man, we find him exactly on a par with the child or the animal. A violent stimulus produces at once violent, or at any rate manifest, action, facial or other. There is a conversion of nerve-force into muscular movement, directly following a stimulus, whether this be one exciting bodily pain, as a blow, or mental, as a shocking sight or piece of news But, when we examine the mind of man in its highest development we find in the highly-intellectual individual certain emotions, which are clearly the feelings corresponding to the very complex ideas acquired and organized by years of culture and training. We read of the Ethical Emotion, or moral sense; of the Æsthetic Emotion; of other emotions arising out of the Intellect. But all these appear to illustrate and to be illustrated by what I have said concerning the simple emotions. Here, instead of a single and simple idea-centre which, when excited, at once responds in outward bodily movement, we have an extremely complex chain of ideas. The training and preparation of years, as well as previous organization, are required to bring about in the brain that complex series of ideas which represents a knowledge of the tine arts, and which is presupposed when we speak of experiencing aesthetic emotion. Instead of a single and lowly-endowed centre, such as we may find in children or animals, we have a coordinated and complex chain of high centres, which, when excited, respond not in immediate bodily movement accompanied by bodily feeling, but in deliberate action, the result of reflection; in intellectual, rather than bodily movement. For the activity of thought must be due to a stimulus applied to the intellectual centres, no less than the activity of body: and not only the activity of thought, but action in thought, the desire for action of body which would become action, did not some other reflection intervene, must also be set down as an outcome of nerve-force emitted by some centre or centres, which have been set in motion by a stimulus. Repressed action, whether in thought alone, or in the clinched hands and quivering lips of suppressed passion, must be taken as an emission of force. The complex coordination of ideas arrived at after years of study and experience, which causes the connoisseur the keen delight experienced when he gazes at a rare Rembrandt etching or a matchless coin, must include within itself the feelings belonging to it. The uninitiated cannot feel the delight, because he possesses not the ideas. We cannot suppose that the feeling resides in one part of the brain, and the ideas in another; rather would it appear that the stimulation of the ideas by the sight of the object causes the feeling. The ideas exist in the brain as knowledge, but when called into action we have the feeling of pleasure or pain which is special and appropriate to such a group of ideas, in addition to the knowledge and the ideas themselves. It may be said that emotions are so varied that they must require a special organization; that the emotion of delight just named is something totally different from such a feeling as self-denial. But we must remember that ideas are formed in the educated mind into large and complex groups—associated ideas, as they are called—and that these act as units, just as groups of muscles always act together; and the association of the one, when established, cannot be disjoined, any more than that of the other. Consequently, stimulation of such a group of ideas calls it into action, and then arises its special feeling, depending in degree upon the amount of the stimulation and the nerve-force extricated in the process. And these very complex emotions may be reduced by analysis to much simpler feelings—to feelings of self-advantage or self-detriment, the pleasure or pain which is at the bottom of all feeling, of all stimulation of the nervous system strong enough to cause feeling to come into consciousness. Looking upon the whole conscious brain as self, its feeling varies from self-good to self-ill; its various and special portions, groups of nerve-cells and nerve-centres, being stimulated into special feelings which are yet all of them resolvable into the simple elements. If we look at the phenomena of insanity we shall see this illustrated by the fact that the feelings and delusions of the insane always have reference to self.
I have traced the higher emotions up from the mere bodily feelings, nay, even from the sensations of the special senses, and have affirmed that they all vary according to the amount of stimulation which each centre receives, while their quality depends on the special properties of the centre or centres. The phenomena of two of the senses, at any rate, confirm this view. One person hears a sound which another cannot. This is because the centre of hearing in the deaf person is not sufficiently stimulated by a sound, the vibrations of which are too slow for him, though not too slow for the other to perceive. Similarly, some people cannot recognize redness as a color. On analyzing the color red, we find it to be the color at one end of the spectrum, an inch of which gives the smallest number of waves of light, and to this amount of stimulation some eyes are insensible, just as the eyes of all men are insensible to the rays beyond red, which we discover by the galvanometer, though they do not excite our optic centres as light. As no two persons feel alike, so no two see or hear alike. The centres of sight and hearing of one man are stimulated by vibrations which fail to excite those of another. There may be colors and there may be harmonies all around us in the universe, of which we know nothing, but of which the more sensitive organs of what are called the lower animals may be keenly conscious. It may be that these animals are only by us called dumb because we ourselves are deaf.
The stimuli, then, which excite the nerve-centres of man, produce various feelings and emotions according to the quality and properties of the centre excited. But, as I have said, the feeling will vary according not only to the quality of the centre, but also according to the condition it may happen to be in at the time, or that to which it may be brought by the stimulation it experiences. To elucidate this, we must consider what we know of the physiology of nerve-structures and their functions.
When studying the physiology of nerve-action as we see it in animals, children, and men, and the pathology as we see it in various nervous disorders, as acute insanity, 'delirium tremens, and the like, we soon become aware of the fact that the well-being of the entire nervous system depends mainly on its renovation during a state of repose; and that for the higher portion of the brain, at any rate, this state of repose and rest is synonymous with healthy sleep. Round the phenomena of sleep, and its causes and conditions, are grouped many of the problems which have to be solved by the physiologist who has to investigate the action of the nerve-centres, and the physician who has to cure their disorders. The state or condition of a nerve-centre, which I have called the force, will be dependent upon the amount of rest and sleep which it enjoys, supplemented by two other restorers of force, food and warmth; which must also be taken into consideration.
Observation teaches us that all animals sleep after a certain period of bodily fatigue, which varies according to the individual, the young requiring sleep more quickly than the old, and a larger amount. If the fatigue be great, nothing can keep a child or even a man awake. When refreshed by sleep, when the force is again accumulated in the brain, we wake spontaneously, or are awakened by trifling stimuli, as sounds or light. This alternation of sleep and waking is the normal state of health, and absence of sleep is something abnormal: it is a disorder, and must lead to further disorder if prolonged. Sleep is not necessary for the renewal of force in every centre. In very severe muscular exercise mere cessation for a time recruits our force, and enables us to begin again; but for the higher work of the brain sleep is indispensable, and all brain-work, and indeed life itself, must cease, unless by this the force is renewed.
So much does observation teach us of the reparation of the force of the brain during sleep. Experiment, however, enables us to state the physiological condition of the brain in sleep, and so to analyze further the production and expenditure of this nerve-force. In sleep, as we have seen, it is produced and accumulated; in active waking hours it is expended. In sleep, the arterial circulation of the brain falls to a certain point, and metamorphosis consequently is reduced to a minimum. When the brain is acting, even in dreams, the blood-flow increases both in arteries and veins. To promote sleep, we seek to diminish this arterial current; until this is done, sleep comes not. The two things which chiefly produce sleep in a healthy man or animal are fatigue and food. After a hearty meal, or after great fatigue endured for many waking hours, it will be difficult to rouse him from sleep, and when roused he will be torpid and inactive, and will fall back into sleep easily. His brain will be emptied of blood, and ordinary stimuli, as light, sound, and movement of others, will not bring back the blood to his brain: moreover, his blood will contain less oxygen. When sufficient hours have been passed in sleep, slight stimuli are enough to wake him, such as a trilling noise or a light; nay, he may wake or seem to wake "of his own accord." The blood returns to the brain highly oxygenized, and the brain is alive and energetic, ready to expend in action the force it has accumulated in the period of its rest.
Now, be it observed, this force is accumulated by the brain in sleep, when the blood-supply is at its minimum and contains the least oxygen. Oxidation of brain, then, implies expenditure, not accumulation of force. Stimulation of brain increases the blood-flow and activity, ubi stimulus ibifluxus. But this activity cannot go on long, and material for new work cannot be provided, unless the blood-flow be reduced to the sleeping-point, and the oxygen in the blood cease to be consumed.
In the creation and restoration of nerve-force, food and heat are to sleep both the supplement and the complement; without all these the full energy of brain-life cannot manifest itself, except for a very limited time, and each will vary in amount according as the other two are supplied in greater or less quantities. To resist the cold of a northern climate, the Esquimaux consumes at a meal that which would feed a Hindoo for a month. If he did not, the bitter winter would bring to him, no less than to the animals hybernating around him, sleep from which he would not wake again. The intense desire for sleep felt by persons exposed to great cold is closely akin to that produced by overwhelming fatigue: the whole nerve-force is consumed in either case and cannot be replaced. In those suffering from cold, the loss may be met by warmth or by food; in those worn out by fatigue, sleep alone is the restorer. How completely the brain is upset by cold we may learn from the striking narrative of the Arctic voyager Dr. Kane, who tells us, after a journey of eighty or ninety miles over the ice at a mean temperature of minus 41°.2: "We were quite delirious and had ceased to entertain a sane apprehension of the circumstances about us." "Our strength failed us, and we began to lose our self-control. . . We fell half-sleeping on the snow. I could not prevent it. Strange to say, it refreshed us. I ventured upon the experiment myself, making Riley wake me at the end of three minutes; and I felt so much benefited by it that I timed the men in the same way. They sat on the runners of the sledge, fell asleep instantly, and were forced to wakefulness when their three minutes were out."
The fact, that pleasure and pain depend on fatigue and the consumption of this nerve-force, is closely connected with two other phenomena: one, that the stimulation of any nerve-centre, if repeated, loses somewhat of its effect; the other, that the same stimulus, if prolonged or intensified, may cause every variety of feeling from pleasure to extreme pain. The first phenomenon is expressed in the language of every-day life, when we say there is nothing that we may not "get used to." We get used to sights, to sounds, to tastes, to smells, to the endurance of bodily pain. It may be stated as an almost constant fact that the same thing repeated, the centre again stimulated with the same stimulus, always loses somewhat of its effect, and consequently less force is expended. We endure the excitation better and feel less fatigued, whatever it be. If by any chance, however, through illness or other cause, our stock of force becomes lessened, we find that we cannot so well endure our habitual stimuli, and they become painful instead of pleasant. Our feelings, then, are regulated partly by the amount of stimulation, partly by the condition in which our centres are when stimulated; and that which applies to pain applies also to pleasure. Pleasurable excitations when repeated lose their charm, or they fail to please us when a disordered liver or a headache makes us dismal.
The second phenomenon is different. Although an excitation repeated loses its effect, yet an excitation prolonged without cessation passes from pleasure to pain without this process ever being reversed.
There is no voluntary action, whether mental or bodily, which does not in time cause fatigue; but it will be found that actions accompanied with direct emotion fatigue the soonest. Almost all bodily or mental processes are accompanied by some amount of feeling or emotion. They are pleasant to us or distasteful; we may be wearied of doing them, or wearied by doing them, according as the mind or the body is fatigued. In either case the process is the same, though the centre which experiences the discomfort is different. The pleasantest occupations or amusements may cause such sheer bodily fatigue that we can do them no longer, and to attempt it causes pain. It would appear that every thing carried to this point—to the extent of exhausting the nerve-force of the centre stimulated—causes discomfort or pain, which is only to be removed by cessation of the particular stimulus, and the substitution of another, stimulating other centres, or by the rest of the whole nervous system. This brings me to the consideration of another point, namely, that violent stimulation of a centre exhausts the nerve-force, not of that centre only, but of the whole nervous system. A terrible shock may so use up the nerve-force that the individual falls senseless, or, short of this, he may yet be so paralyzed with fear or grief that he loses all muscular power, or he may be so violently moved that the great exertions which he makes only last for a short time. We all know that for a long-sustained muscular effort the mind must be tranquil, and free from emotion, and the muscular movements must be regular and even, and free from spasmodic and violent action. How it is that the nerve-force of the whole system is poured out in this or that form of emotion, or idea, we see, but cannot trace the process. Nevertheless, it is a fact that two great displays of force cannot coexist; violent muscular exertion and intense thought cannot go on together; the thinker sits, or stands, abstracted, motionless. The man who is rowing or running a race cannot command his thoughts; ideas come and go through his mind, but he cannot keep up a continuous current of mental work. His force is being expended on bodily movement.
What is the answer to those who say they believe that emotions reside in this or that part of the brain? We may object, first, that every attempt to locate emotions has signally failed, from the days of Gall, Spurzheim, and Combe, to those of Schroder van der Kolk. Some have separated the seat of emotion from the seat of the consciousness thereof, and have placed the latter in the sensory ganglia. Others have placed emotions in the hemispheres alone, and so would deny every thing of the kind to those beings which have no cerebral hemispheres; yet we see considerable emotional feeling manifested by such creatures as the ant and the bee.
Secondly, by an analysis of emotions we may perceive that there is no real line of demarcation between them and mere feelings of a much lower order, and that one and the other belong to the action of the moment, and not to any past or future time. If we are watching, say, a splendid sunset, we experience a feeling of intense delight as the heavens are lit in gorgeous color. The following day we may recall the scene, but we do not feel the pleasure. We remember the pleasure, but it remains, like the scene, only as an idea, it is not now a feeling. Now, few, I presume, would assert that the perception of this sight resides in one part of the brain, and the* feeling attending it in another. If this were so, we ought to be able to excite the feeling by means of the idea preserved in the memory; but this we cannot do. The original stimulation causes the pleasure, and this vanishes, never again to return. It is only in complexity that the highest emotions differ from this simple feeling; they involve more ideas, more acquisitions, previously laid up, but the effect of the immediate stimulation is the same; this it is which, according to its intensity, causes the pleasure or pain. The same may be said of pain experienced; we may recall the memory of it, but this is not the same thing; even the memory may be distressing and saddening, but this is different from the acute pang which we suffer at the first shock.
The brain is a sealed book far more than some of the other organs of the body, as the lungs and heart; but, if we could inspect it at work, it is not probable that we should be able to note those molecular changes, which, nevertheless, we believe to take place when mental action is going on. What we should see, however, would be alterations in the circulation of the blood. We should see that the whole circulation, or portions of it, would be affected by mental excitation, by the stimulation of the various cells or groups of cells, which we call nerve-centres. We should see that a piece of news, a disaster, an impending trouble or difficulty, causes a man to lay awake at night, and we should know that he lies awake because his brain circulation, either through the whole or in parts of his cerebral hemispheres, is higher than admits of sleep. There is an extrication of force going on in the shape of thought, there is a flow of blood going to the excited part. We cannot see all this, however, but we can and do see how emotion causes the face to flush and the pulse to quicken, how those who lie awake suffer from heat of head and suffusion of eyes, how emotion increases the lachrymal secretion, the lacteal, and others. And when we say that emotion does these things, we merely mean that something or other has stimulated the brain into producing these phenomena, and that along with the stimulus the feeling of grief or shame or anger coexists.
If all this be true, it may perchance throw some light upon many of the phenomena of disordered mind and brain: it may help us to understand why, with almost the same delusion, e.g., that the newspapers are writing about him, one man will be exultant, another angry, another depressed; it may explain why the same man is at one time maniacal, at another melancholic. Lack of force may account for the wretched feeling of the hypochondriac and the hysterical, for the mental pain which many feel when they are below par: and a proneness to part with force, to convert it into action, may be the condition of the centres of those who are excitable and impulsive, a condition analogous to that brought about in certain centres by such drugs as strychnia, by such diseases as epilepsy and convulsions, or evidenced by such an affection as stammering.—Fortnightly Review.
- 1 "Arctic Explorations," i, 198.