§ 20. As we have said, the will proclaims itself primarily in the voluntary movements of our own body, as the inmost nature of this body, as that which it is besides being object of perception, idea. For these voluntary movements are nothing else than the visible aspect of the individual acts of will, with which they are directly coincident and identical, and only distinguished through the form of knowledge into which they have passed, and in which alone they can be known, the form of idea.
But these acts of will have always a ground or reason outside themselves in motives. Yet these motives never determine more than what I will at this time, in this place, and under these circumstances, not that I will in general, or what I will in general, that is, the maxims which characterise my volition generally. Therefore the inner nature of my volition cannot be explained from these motives; but they merely determine its manifestation at a given point of time: they are merely the occasion of my will showing itself; but the will itself lies outside the province of the law of motivation, which determines nothing but its appearance at each point of time. It is only under the presupposition of my empirical character that the motive is a sufficient ground of explanation of my action. But if I abstract from my character, and then ask, why, in general, I will this and not that, no answer is possible, because it is only the manifestation of the will that is subject to the principle of sufficient reason, and not the will itself, which in this respect is to be called groundless. At this point I presuppose Kant’s doctrine of the empirical and intelligible character, and also my own treatment of the subject in “The Fundamental Problems of Ethics,” pp. 48, 58, and 178, et seq., of first edition (p. 174, et seq., of second edition). I shall also have to speak more fully on the question in the Fourth Book. For the present, I have only to draw attention to this, that the fact of one manifestation being established through another, as here the deed through the motive, does not at all conflict with the fact that its real nature is will, which itself has no ground; for as the principle of sufficient reason in all its aspects is only the form of knowledge, its validity extends only to the idea, to the phenomena, to the visibility of the will, but not to the will itself, which becomes visible.
If now every action of my body is the manifestation of an act of will in which my will itself in general, and as a whole, thus my character, expresses itself under given motives, manifestation of the will must be the inevitable condition and presupposition of every action. For the fact of its manifestation cannot depend upon something which does not exist directly and only through it, which consequently is for it merely accidental, and through which its manifestation itself would be merely accidental. Now that condition is just the whole body itself. Thus the body itself must be manifestation of the will, and it must be related to my will as a whole, that is, to my intelligible character, whose phenomenal appearance in time is my empirical character, as the particular action of the body is related to the particular act of the will. The whole body, then, must be simply my will become visible, must be my will itself, so far as this is object of perception, an idea of the first class. It has already been advanced in confirmation of this that every impression upon my body also affects my will at once and immediately, and in this respect is called pain or pleasure, or, in its lower degrees, agreeable or disagreeable sensation; and also, conversely, that every violent movement of the will, every emotion or passion, convulses the body and disturbs the course of its functions. Indeed we can also give an etiological account, though a very incomplete one, of the origin of my body, and a somewhat better account of its development and conservation, and this is the substance of physiology. But physiology merely explains its theme in precisely the same way as motives explain action. Thus the physiological explanation of the functions of the body detracts just as little from the philosophical truth that the whole existence of this body and the sum total of its functions are merely the objectification of that will which appears in its outward actions in accordance with a motive, as the establishment of the individual action through the motive and the necessary sequence of the action from the motive conflicts with the fact that action in general, and according to its nature, is only the manifestation of a will which itself has no ground. If, however, physiology tries to refer even these outward actions, the immediate voluntary movements, to causes in the organism,—for example, if it explains the movement of the muscles as resulting from the presence of fluids (“like the contraction of a cord when it is wet,” says Reil in his “Archiv für Physiologie,” vol. vi. p. 153), even supposing it really could give a thorough explanation of this kind, yet this would never invalidate the immediately certain truth that every voluntary motion (functiones animales) is the manifestation of an act of will. Now, just as little can the physiological explanation of vegetative life (functiones naturales vitales), however far it may advance, ever invalidate the truth that the whole animal life which thus develops itself is the manifestation of will. In general, then, as we have shown above, no etiological explanation can ever give us more than the necessarily determined position in time and space of a particular manifestation, its necessary appearance there, according to a fixed law; but the inner nature of everything that appears in this way remains wholly inexplicable, and is presupposed by every etiological explanation, and merely indicated by the names, force, or law of nature, or, if we are speaking of action, character or will. Thus, although every particular action, under the presupposition of the definite character, necessarily follows from the given motive, and although growth, the process of nourishment, and all the changes of the animal body take place according to necessarily acting causes (stimuli), yet the whole series of actions, and consequently every individual act, and also its condition, the whole body itself which accomplishes it, and therefore also the process through which and in which it exists, are nothing but the manifestation of the will, the becoming visible, the objectification of the will. Upon this rests the perfect suitableness of the human and animal body to the human and animal will in general, resembling, though far surpassing, the correspondence between an instrument made for a purpose and the will of the maker, and on this account appearing as design, i.e., the teleological explanation of the body. The parts of the body must, therefore, completely correspond to the principal desires through which the will manifests itself; they must be the visible expression of these desires. Teeth, throat, and bowels are objectified hunger; the organs of generation are objectified sexual desire; the grasping hand, the hurrying feet, correspond to the more indirect desires of the will which they express. As the human form generally corresponds to the human will generally, so the individual bodily structure corresponds to the individually modified will, the character of the individual, and therefore it is throughout and in all its parts characteristic and full of expression. It is very remarkable that Parmenides already gave expression to this in the following verses, quoted by Aristotle (Metaph. iii. 5):—
Ὁς γαρ ἑκαστος εχει κρασιν μελεων πολυκαμπτων
Τως νοος ανθρωποισι παρεστηκεν; το γαρ αυτο
Εστιν, ὁπερ φρονεει, μελεων φυσις ανθρωποισι
Και πασιν και παντι; το γαρ πλεον εστι νοημα.
(Ut enim cuique complexio membrorum flexibilium se habet, ita mens hominibus adest: idem namque est, quod sapit, membrorum natura hominibus,