That hence results such failure of guidance by pleasures and pains as is daily exhibited, we discover on observing in what parts of conduct the failure is most conspicuous. As above shown, the pleasurable and painful sensations are fairly well adjusted to the peremptory physical requirements: the benefits of conforming to the sensations which prompt us in respect of nutrition, respiration, maintenance of temperature, etc., immensely exceed the incidental evils, and such misadjustments as occur may be ascribed to the change from the outdoor life of the primitive man to the indoor life which the civilized man is often compelled to lead. It is the emotional pleasures and pains which are in so considerable a degree out of adjustment to the needs of life as carried on in society, and it is of these that the readjustment is made in the way above shown, so tardy because so difficult.
From the biological point of view, then, we see that the connections between pleasure and beneficial action and between pain and detrimental action, which arose when sentient existence began, and have continued among animate creatures up to man, are generally displayed in him also throughout the lower and more completely organized part of his nature; and must be more and more fully displayed throughout the higher part of his nature, as fast as his adaptation to the conditions of social life increases.
§ 36. Biology has a further judgment to pass on the relations of pleasures and pains to welfare. Beyond the connections between acts beneficial to the organism and the pleasures accompanying performance of them, and between acts detrimental to the organism and the pains causing desistance from them, there are connections between pleasure in general and physiological exaltation, and between pain in general and physiological depression. Every pleasure increases vitality; every pain decreases vitality. Every pleasure raises the tide of life; every pain lowers the tide of life. Let us consider, first, the pains.
By the general mischiefs that result from submission to pains, I do not mean those arising from the diffused effects of local organic lesions, such as follow an aneurism caused by intense effort spite of protesting sensations, or such as follow the varicose veins brought on by continued disregard of fatigue in the legs, or such as follow the atrophy set up in muscles that are persistently exerted when extremely weary; but I mean the general mischiefs caused by that constitutional disturbance which pain forthwith sets up. These are conspicuous when the pains are acute, whether they be sensational or emotional.
Bodily agony long borne produces death by exhaustion. More frequently, arresting the action of the heart for a time, it causes that temporary death we call fainting. On other occasions vomiting is a consequence. And where such manifest derangements do not result, we still, in the pallor and trembling, trace the general prostration. Beyond the actual loss of life caused by subjection to intense cold there are depressions of vitality less marked caused by cold less extreme—temporary enfeeblement following too long an immersion in icy water; enervation and pining away consequent on inadequate clothing. Similarly is it with submission to great heat: we have lassitude reaching occasionally to exhaustion; we have, in weak persons, fainting, succeeded by temporary debilitation; and in steaming tropical jungles Europeans contract fevers which, when not fatal, often entail life-long incapacities. Consider, again, the evils that follow violent exertion continued in spite of painful feelings—now a fatigue which destroys appetite or arrests digestion if food is taken, implying failure of the reparative processes when they are most needed; and now a prostration of the heart, here lasting for a time and there, where the transgression has been repeated day after day, made permanent: reducing the rest of life to a lower level.
No less conspicuous are the depressing effects of emotional pains. There are occasional cases of death from grief; and in other cases the mental suffering which a calamity causes, like bodily suffering, shows its effects by syncope. Often a piece of bad news is succeeded by sickness; and continued anxiety will produce loss of appetite, perpetual indigestion and diminished strength. Excessive fear, whether aroused by physical or moral danger, will, in like manner, arrest for a time the processes of nutrition; and, not unfrequently, in pregnant women brings on miscarriage; while, in less extreme cases, the cold perspiration and unsteady hands indicate a general lowering of the vital activities, entailing partial incapacity of body or mind or both. How greatly emotional pain deranges the visceral actions is shown us by the fact that incessant worry is not unfrequently followed by jaundice. And here, indeed, the relation between cause and effect happens to have been proved by direct experiment. Making such arrangements that the bile-duct of a dog delivered its product outside the body, Claude Bernard observed that so long as he petted the dog and kept him in good spirits, secretion went on at its normal rate; but on speaking angrily, and for a time so treating him as to produce depression, the flow of bile was arrested.
Should it be said that evil results of such kinds are proved to occur only when the pains, bodily or mental, are great, the reply is that in healthy persons the injurious perturbations caused by small pains, though not easily traced, are still produced; and that in those whose vital powers are much reduced by illness, slight physical irritations and trifling moral annoyances, often cause relapses.
Quite opposite are the constitutional effects of pleasure. It sometimes, though rarely, happens that in feeble persons intense pleasure—pleasure that is almost pain—gives a nervous shock that is mischievous; but it does not do this in those who are undebilitated by voluntary or enforced submission to actions injurious to the organism. In the normal order, pleasures, great and small, are stimulants to the processes by which life is maintained.
Among the sensations may be instanced those produced by bright light. Sunshine is enlivening in comparison with gloom—even a gleam excites a wave of pleasure; and experiments have shown that sunshine raises the rate of respiration: raised respiration being an index of raised vital activities in general. A warmth that is agreeable in degree favors the heart's action, and furthers the various functions to which this is instrumental. Though those who are in full vigor and fitly clothed can maintain their temperature in winter, and can digest additional food to make up for the loss of heat, it is otherwise with the feeble; and, as vigor declines, the beneficence of warmth becomes conspicuous. That benefits accompany the agreeable sensations produced by fresh air, and the agreeable sensations that accompany muscular action after due rest, and the agreeable sensations caused by rest after exertion cannot be questioned. Receipt of these pleasures conduces to the maintenance of the body in fit condition for all the purposes of life.
More manifest still are the physiological benefits of emotional pleasures. Every power, bodily and mental, is increased by "good spirits," which is our name for a general emotional satisfaction. The truth that the fundamental vital actions—those of nutrition—are furthered by laughter-moving conversation, or rather by the pleasurable feeling causing laughter, is one of old standing; and every dyspeptic knows that in exhilarating company, a large and varied dinner, including not very digestible things, may be eaten with impunity, and, indeed, with benefit, while a small, carefully chosen dinner of simple things, eaten in solitude, will be followed by indigestion. This striking effect on the alimentary system is accompanied by effects, equally certain though less manifest, on the circulation and the respiration. Again, one who, released from daily labors and anxieties, receives delights from fine scenery or is enlivened by the novelties he sees abroad, comes back showing by toned-up face and vivacious manner, the greater energy with which he is prepared to pursue his avocation. Invalids especially, on whose narrowed margin of vitality the influence of conditions is most visible, habitually show the benefits derived from agreeable states of feeling. A lively social circle, the call of an old friend, or even removal to a brighter room, will, by the induced cheerfulness, much improve the physical state. In brief, as every medical man knows, there is no such tonic as happiness.