We note also, in ourselves directly and by the evidence of consciousness, in others indirectly and by induction, the existence of certain states which are agreeable, painful, or mixed, with their modes or shades, extremely variable in quality and in intensity.
Of these two groups—the motor manifestations on one side, the pleasures, pains, and their compounds on the other side—which is fundamental? Can we put them on the same level, and if we cannot, which is that which supports the other?
My reply to this question is clear: it is the motor manifestations which are essential. In other words, what are called agreeable or painful states only constitute the superficial part of the life of feeling, of which the deep element consists in tendencies, appetites, needs, desires, translated into movements. Most classical treatises (and even some others) say that sensibility is the faculty of experiencing pleasure and pain. I should say, using the same terminology, that sensibility is the faculty of tending or desiring, and consequently of experiencing pleasure and pain. There is nothing mysterious in the tendency; it is a movement or an arrest of movement in the nascent stage. I employ this word “tendency” as synonymous with needs, appetites, instincts, inclinations, desires; it is the generic term of which the others are varieties; it has the advantage over them of embracing at the same time both the psychological and physiological aspects of the phenomenon. All the tendencies suppose a motor innervation; they translate the needs of the individual, whatever they may be, physical or mental; the basis, the root of the affective life is in them, not in the consciousness of pleasure and pain which accompanies them according as they are satisfied or opposed. These agreeable or painful states are only signs and indications; and just as symptoms reveal to us the existence of a disease, and not its essential nature, which must be sought in the hidden lesions of the tissues, organs, and functions, so pleasure and pain are only effects which must guide us in the search and determination of causes hidden in the region of the instincts. If the contrary opinion has generally prevailed, and priority been accorded to the study of agreeable and painful manifestations considered as the essential element in the emotional life and serving to define it, that is the result of a bad method, of an exclusive faith in the evidence of consciousness, of a common illusion which consists in believing that the conscious portion of an event is its principal portion, but especially the consequence of the radically false idea that the bodily phenomena which accompany all states of feeling are factors that are negligible and external, foreign to psychology, and without interest for it.
For the present what has just been said is only an affirmation; the proofs will come later, and will occupy the whole of this book; at the outset it is only necessary to indicate clearly the position taken up. We may now follow the evolution of the life of feeling in its chief stages, which are—pre-conscious sensibility, the appearance of the primitive emotions, their transformation either into complex and abstract emotions or into that stable and chronic state which constitutes the passions.
I.
The first period is that of protoplasmic, vital, organic pre-conscious sensibility. We know that the organism has its memory; it preserves certain impressions, certain normal or morbid modifications; it is capable of adaptation: this point has been well established by Bering (who had been preceded by Laycock and Jessen). It is the outline of the superior form of psychic conscious memory. In the same way there exists an inferior unconscious form—organic sensibility—which is the preparation and the outline of superior conscious emotional life. Vital sensibility is to conscious feeling what organic memory is to memory in the ordinary sense of the word.
This vital sensibility is the capacity to receive stimuli and to re-act to them. In a well-known memoir, now of ancient date,[[2]] Claude Bernard wrote: “Philosophers generally only know and admit conscious sensibility, that which their ego bears witness to. It is for them the psychic modification, pleasure or pain, determined by external modifications.... Physiologists necessarily place themselves at another point of view. They have to study the phenomenon objectively, under all the forms which it puts on. They observe that at the moment when a modifying agent acts on man, it not only provokes pleasure and pain, it not only affects the soul: it affects the body, it determines other re-actions besides the psychic re-actions, and these automatic re-actions, far from being an accessory part of the phenomenon, are on the contrary its essential element.” Then he showed experimentally that the employment of anæsthetics, pushed to an extreme, first abolished conscious sensibility, then the unconscious sensibility of the intestines and glands, then muscular irritability, finally the lively movements of the epithelial tissue. In the same way among plants: under the influence of ether the sensitive plant loses its singular properties, seeds cease to germinate, yeast to ferment, etc. Whence follows the conclusion that sensibility resides, not in the organs or tissues, but in their anatomical elements.
Since then these investigations into protoplasmic sensibility have been pursued with much ardour among micro-organisms. These beings, sometimes animal, sometimes vegetable, are simple masses of protoplasm, generally monocellular, appearing homogeneous, without differentiation of tissues. Now very varied tendencies have been found among these organisms. Some seek light, others flee from it persistently. The protoplasmic mass of myxomycetes which live in the bark of the oak, if placed in a watch-glass full of water, remain there in repose; but if sawdust is placed around them they immediately emigrate towards it as if seized by home-sickness. The actynophrys acts in the same way with regard to starch. Bacteria can discover even the trillionth part of a milligram of oxygen in a neighbouring body. Certain sedentary ciliated creatures appear to choose their food. Some also have thought that they detected an elective tendency in the movement which draws the male ovule towards the female ovule. I have only recalled a few of the many facts which have been enumerated.
If it is necessary to mention other examples, I may refer to the case studied in our own days under the name of “phagocytosis.” The struggle for life goes on, not only among individuals, but also among the anatomical elements which constitute the individual. Every tissue—muscular, connective, adipose, etc.—possesses phagocytes (devouring cells), of which the duty consists in devouring and destroying old or enfeebled cells of the same kind. Besides these special phagocytes there are general phagocytes, such as the white corpuscles of the blood, which come to the help of the others when they are not equal to their task. They stand against the pathogenic microbes, waging upon them an internal struggle, and opposing the invasion of infectious germs. This apparently teleological property seems at first very surprising. Later investigations have shown that the phagocytes are endowed with a sensibility (called chemiotaxic), owing to which they are able to distinguish the chemical composition of their environment and to approach it or leave it accordingly; deteriorated tissues attract certain of them which incorporate the feeble or dead cells, while the healthy and vigorous elements are perhaps able to defend themselves by secreting some substance which preserves them from phagocytosis.
These facts, taken from among many others to which I shall again have to refer when dealing with the sexual instinct, have been interpreted in two very different ways: one psychological, the other chemical.