of the pupils of the eyes as the light is increased is due to stimuli, but it passes into movement which is due to motive; for it takes place, because too strong lights would affect the retina painfully, and to avoid this we contract the pupils. The occasion of an erection is a motive, because it is an idea, yet it operates with the necessity of a stimulus, i.e., it cannot be resisted, but we must put the idea away in order to make it cease to affect us. This is also the case with disgusting things, which excite the desire to vomit. Thus we have treated the instinct of animals as an actual link, of quite a distinct kind, between movement following upon stimuli, and action following upon a known motive. Now we might be asked to regard breathing as another link of this kind. It has been disputed whether it belongs to the voluntary or the involuntary movements, that is to say, whether it follows upon motive or stimulus, and perhaps it may be explained as something which is between the two. Marshall Hall (“On the Diseases of the Nervous System,” § 293 sq.) explains it as a mixed function, for it is partly under the influence of the cerebral (voluntary), and partly under that of the spinal (non-voluntary) nerves. However, we are finally obliged to number it with the expressions of will which result from motives. For other motives, i.e., mere ideas, can determine the will to check it or accelerate it, and, as is the case with every other voluntary action, it seems to us that we could give up breathing altogether and voluntarily suffocate. And in fact we could do so if any other motive influenced the will sufficiently strongly to overcome the pressing desire for air. According to some accounts Diogenes actually put an end to his life in this way (Diog. Laert. VI. 76). Certain negroes also are said to have done this (F. B. Osiander “On Suicide” [1813] pp. 170–180). If this be true, it affords us a good example of the influence of abstract motives, i.e., of the victory of distinctively rational over merely animal will. For, that breathing is at least partially conditioned by cerebral activity is shown by the fact that the primary cause of death from prussic acid is that it paralyses the brain, and so, indirectly, restricts the breathing; but if the breathing be artificially maintained till the stupefaction of the brain has passed away, death will not ensue. We may also observe in passing that breathing affords us the most obvious example of the fact that motives act with just as much necessity as stimuli, or as causes in the narrowest sense of the word, and their operation can only be neutralised by antagonistic motives, as action is neutralised by re-action. For, in the case of breathing, the illusion that we can stop when we like is much weaker than in the case of other movements which follow upon motives; because in breathing the motive is very powerful, very near to us, and its satisfaction is very easy, for the muscles which accomplish it are never tired, nothing, as a rule, obstructs it, and the whole process is supported by the most inveterate habit of the individual. And yet all motives act with the same necessity. The knowledge that necessity is common to movements following upon motives, and those following upon stimuli, makes it easier for us to understand that that also which takes place in our bodily organism in accordance with stimuli and in obedience to law, is yet, according to its inner nature—will, which in all its manifestations, though never in itself, is subordinated to the principle of sufficient reason, that is, to necessity.32 Accordingly, we shall not rest contented with recognising that animals, both in their actions and also in their whole existence, bodily structure and organisation, are manifestations of will; but we shall extend to plants also this immediate knowledge of the essential nature of things which is given to us alone. Now all the movements of plants follow upon stimuli; for the absence of knowledge, and the movement following upon motives which is conditioned by knowledge, constitutes the only essential difference between animals and plants. Therefore, what appears for the idea as plant life, as mere vegetation, as blindly impelling force, we shall claim, according to its inner nature, for will, and recognise it as just that which constitutes the basis of our own phenomenal being, as it expresses itself in our actions, and also in the whole existence of our body itself.
It only remains for us to take the final step, the extension of our way of looking at things to all those forces which act in nature in accordance with universal, unchangeable laws, in conformity with which the movements of all those bodies take place, which are wholly without organs, and have therefore no susceptibility for stimuli, and have no knowledge, which is the necessary condition of motives. Thus we must also apply the key to the understanding of the inner nature of things, which the immediate knowledge of our own existence alone can give us, to those phenomena of the unorganised world which are most remote from us. And if we consider them attentively, if we observe the strong and unceasing impulse with which the waters hurry to the ocean, the persistency with which the magnet turns ever to the north pole, the readiness with which iron flies to the magnet, the eagerness with which the electric poles seek to be re-united, and which, just like human desire, is increased by obstacles; if we see the crystal quickly and suddenly take form with such wonderful regularity of construction, which is clearly only a perfectly definite and accurately determined impulse in different directions, seized and retained by crystallisation; if we observe the choice with which bodies repel and attract each other, combine and separate, when they are set free in a fluid state, and emancipated from the bonds of rigidness; lastly, if we feel directly how a burden which hampers our body by its gravitation towards the earth, unceasingly presses and strains upon it in pursuit of its one tendency; if we observe all this, I say, it will require no great effort of the imagination to recognise, even at so great a distance, our own nature. That which in us pursues its ends by the light of knowledge; but here, in the weakest of its manifestations, only strives blindly and dumbly in a one-sided and unchangeable manner, must yet in both cases come under the name of will, as it is everywhere one and the same—just as the first dim light of dawn must share the name of sunlight with the rays of the full mid-day. For the name will denotes that which is the inner nature of everything in the world, and the one kernel of every phenomenon.
Yet the remoteness, and indeed the appearance of absolute difference between the phenomena of unorganised nature and the will which we know as the inner reality of our own being, arises chiefly from the contrast between the completely determined conformity to law of the one species of phenomena, and the apparently unfettered freedom of the other. For in man, individuality makes itself powerfully felt. Every one has a character of his own; and therefore the same motive has not the same influence over all, and a thousand circumstances which exist in the wide sphere of the knowledge of the individual, but are unknown to others, modify its effect. Therefore action cannot be predetermined from the motive alone, for the other factor is wanting, the accurate acquaintance with the individual character, and with the knowledge which accompanies it. On the other hand, the phenomena of the forces of nature illustrate the opposite extreme. They act according to universal laws, without variation, without individuality in accordance with openly manifest circumstances, subject to the most exact predetermination; and the same force of nature appears in its million phenomena in precisely the same way. In order to explain this point and prove the identity of the one indivisible will in all its different phenomena, in the weakest as in the strongest, we must first of all consider the relation of the will as thing-in-itself to its phenomena, that is, the relation of the world as will to the world as idea; for this will open to us the best way to a more thorough investigation of the whole subject we are considering in this second book.33
§ 24. We have learnt from the great Kant that time, space, and causality, with their entire constitution, and the possibility of all their forms, are present in our consciousness quite independently of the objects which appear in them, and which constitute their content; or, in other words, they can be arrived at just as well if we start from the subject as if we start from the object. Therefore, with equal accuracy, we may call them either forms of intuition or perception of the subject, or qualities of the object as object (with Kant, phenomenon), i.e., idea. We may also regard these forms as the irreducible boundary between object and subject. All objects must therefore exist in them, yet the subject, independently of the phenomenal object, possesses and surveys them completely. But if the objects appearing in these forms are not to be empty phantoms, but are to have a meaning, they must refer to something, must be the expression of something which is not, like themselves, object, idea, a merely relative existence for a subject, but which exists without such dependence upon something which stands over against it as a condition of its being, and independent of the forms of such a thing, i.e., is not idea, but a thing-in-itself. Consequently it may at least be asked: Are these ideas, these objects, something more than or apart from the fact that they are ideas, objects of the subject?