(Ut enim cuique complexio membrorum flexibilium se habet, ita mens hominibus adest: idem namque est, quod sapit, membrorum natura hominibus, et omnibus et omni: quod enim plus est, intelligentia est.)30

§ 21. Whoever has now gained from all these expositions a knowledge in abstracto, and therefore clear and certain, of what every one knows directly in concreto, i.e., as feeling, a knowledge that his will is the real inner nature of his phenomenal being, which manifests itself to him as idea, both in his actions and in their permanent substratum, his body, and that his will is that which is most immediate in his consciousness, though it has not as such completely passed into the form of idea in which object and subject stand over against each other, but makes [pg 142] itself known to him in a direct manner, in which he does not quite clearly distinguish subject and object, yet is not known as a whole to the individual himself, but only in its particular acts,—whoever, I say, has with me gained this conviction will find that of itself it affords him the key to the knowledge of the inmost being of the whole of nature; for he now transfers it to all those phenomena which are not given to him, like his own phenomenal existence, both in direct and indirect knowledge, but only in the latter, thus merely one-sidedly as idea alone. He will recognise this will of which we are speaking not only in those phenomenal existences which exactly resemble his own, in men and animals as their inmost nature, but the course of reflection will lead him to recognise the force which germinates and vegetates in the plant, and indeed the force through which the crystal is formed, that by which the magnet turns to the north pole, the force whose shock he experiences from the contact of two different kinds of metals, the force which appears in the elective affinities of matter as repulsion and attraction, decomposition and combination, and, lastly, even gravitation, which acts so powerfully throughout matter, draws the stone to the earth and the earth to the sun,—all these, I say, he will recognise as different only in their phenomenal existence, but in their inner nature as identical, as that which is directly known to him so intimately and so much better than anything else, and which in its most distinct manifestation is called will. It is this application of reflection alone that prevents us from remaining any longer at the phenomenon, and leads us to the thing in itself. Phenomenal existence is idea and nothing more. All idea, of whatever kind it may be, all object, is phenomenal existence, but the will alone is a thing in itself. As such, it is throughout not idea, but toto genere different from it; it is that of which all idea, all object, is the phenomenal appearance, the visibility, [pg 143] the objectification. It is the inmost nature, the kernel, of every particular thing, and also of the whole. It appears in every blind force of nature and also in the preconsidered action of man; and the great difference between these two is merely in the degree of the manifestation, not in the nature of what manifests itself.

§ 22. Now, if we are to think as an object this thing-in-itself (we wish to retain the Kantian expression as a standing formula), which, as such, is never object, because all object is its mere manifestation, and therefore cannot be it itself, we must borrow for it the name and concept of an object, of something in some way objectively given, consequently of one of its own manifestations. But in order to serve as a clue for the understanding, this can be no other than the most complete of all its manifestations, i.e., the most distinct, the most developed, and directly enlightened by knowledge. Now this is the human will. It is, however, well to observe that here, at any rate, we only make use of a denominatio a potiori, through which, therefore, the concept of will receives a greater extension than it has hitherto had. Knowledge of the identical in different phenomena, and of difference in similar phenomena, is, as Plato so often remarks, a sine qua non of philosophy. But hitherto it was not recognised that every kind of active and operating force in nature is essentially identical with will, and therefore the multifarious kinds of phenomena were not seen to be merely different species of the same genus, but were treated as heterogeneous. Consequently there could be no word to denote the concept of this genus. I therefore name the genus after its most important species, the direct knowledge of which lies nearer to us and guides us to the indirect knowledge of all other species. But whoever is incapable of carrying out the required extension of the concept will remain involved in a permanent misunderstanding. For by the word will he understands only that species of it which has hitherto been exclusively [pg 144] denoted by it, the will which is guided by knowledge, and whose manifestation follows only upon motives, and indeed merely abstract motives, and thus takes place under the guidance of the reason. This, we have said, is only the most prominent example of the manifestation of will. We must now distinctly separate in thought the inmost essence of this manifestation which is known to us directly, and then transfer it to all the weaker, less distinct manifestations of the same nature, and thus we shall accomplish the desired extension of the concept of will. From another point of view I should be equally misunderstood by any one who should think that it is all the same in the end whether we denote this inner nature of all phenomena by the word will or by any other. This would be the case if the thing-in-itself were something whose existence we merely inferred, and thus knew indirectly and only in the abstract. Then, indeed, we might call it what we pleased; the name would stand merely as the symbol of an unknown quantity. But the word will, which, like a magic spell, discloses to us the inmost being of everything in nature, is by no means an unknown quantity, something arrived at only by inference, but is fully and immediately comprehended, and is so familiar to us that we know and understand what will is far better than anything else whatever. The concept of will has hitherto commonly been subordinated to that of force, but I reverse the matter entirely, and desire that every force in nature should be thought as will. It must not be supposed that this is mere verbal quibbling or of no consequence; rather, it is of the greatest significance and importance. For at the foundation of the concept of force, as of all other concepts, there ultimately lies the knowledge in sense-perception of the objective world, that is to say, the phenomenon, the idea; and the concept is constructed out of this. It is an abstraction from the province in which cause and effect reign, i.e., from ideas of perception, and means just the causal nature of [pg 145] causes at the point at which this causal nature is no further etiologically explicable, but is the necessary presupposition of all etiological explanation. The concept will, on the other hand, is of all possible concepts the only one which has its source not in the phenomenal, not in the mere idea of perception, but comes from within, and proceeds from the most immediate consciousness of each of us, in which each of us knows his own individuality, according to its nature, immediately, apart from all form, even that of subject and object, and which at the same time is this individuality, for here the subject and the object of knowledge are one. If, therefore, we refer the concept of force to that of will, we have in fact referred the less known to what is infinitely better known; indeed, to the one thing that is really immediately and fully known to us, and have very greatly extended our knowledge. If, on the contrary, we subsume the concept of will under that of force, as has hitherto always been done, we renounce the only immediate knowledge which we have of the inner nature of the world, for we allow it to disappear in a concept which is abstracted from the phenomenal, and with which we can therefore never go beyond the phenomenal.

§ 23. The will as a thing in itself is quite different from its phenomenal appearance, and entirely free from all the forms of the phenomenal, into which it first passes when it manifests itself, and which therefore only concern its objectivity, and are foreign to the will itself. Even the most universal form of all idea, that of being object for a subject, does not concern it; still less the forms which are subordinate to this and which collectively have their common expression in the principle of sufficient reason, to which we know that time and space belong, and consequently multiplicity also, which exists and is possible only through these. In this last regard I shall call time and space the principium individuationis, borrowing an expression from the old schoolmen, and I beg to draw [pg 146] attention to this, once for all. For it is only through the medium of time and space that what is one and the same, both according to its nature and to its concept, yet appears as different, as a multiplicity of co-existent and successive phenomena. Thus time and space are the principium individuationis, the subject of so many subtleties and disputes among the schoolmen, which may be found collected in Suarez (Disp. 5, Sect. 3). According to what has been said, the will as a thing-in-itself lies outside the province of the principle of sufficient reason in all its forms, and is consequently completely groundless, although all its manifestations are entirely subordinated to the principle of sufficient reason. Further, it is free from all multiplicity, although its manifestations in time and space are innumerable. It is itself one, though not in the sense in which an object is one, for the unity of an object can only be known in opposition to a possible multiplicity; nor yet in the sense in which a concept is one, for the unity of a concept originates only in abstraction from a multiplicity; but it is one as that which lies outside time and space, the principium individuationis, i.e., the possibility of multiplicity. Only when all this has become quite clear to us through the subsequent examination of the phenomena and different manifestations of the will, shall we fully understand the meaning of the Kantian doctrine that time, space and causality do not belong to the thing-in-itself, but are only forms of knowing.

The uncaused nature of will has been actually recognised, where it manifests itself most distinctly, as the will of man, and this has been called free, independent. But on account of the uncaused nature of the will itself, the necessity to which its manifestation is everywhere subjected has been overlooked, and actions are treated as free, which they are not. For every individual action follows with strict necessity from the effect of the motive upon the character. All necessity is, as we have already [pg 147] said, the relation of the consequent to the reason, and nothing more. The principle of sufficient reason is the universal form of all phenomena, and man in his action must be subordinated to it like every other phenomenon. But because in self-consciousness the will is known directly and in itself, in this consciousness lies also the consciousness of freedom. The fact is, however, overlooked that the individual, the person, is not will as a thing-in-itself, but is a phenomenon of will, is already determined as such, and has come under the form of the phenomenal, the principle of sufficient reason. Hence arises the strange fact that every one believes himself a priori to be perfectly free, even in his individual actions, and thinks that at every moment he can commence another manner of life, which just means that he can become another person. But a posteriori, through experience, he finds to his astonishment that he is not free, but subjected to necessity; that in spite of all his resolutions and reflections he does not change his conduct, and that from the beginning of his life to the end of it, he must carry out the very character which he himself condemns, and as it were play the part he has undertaken to the end. I cannot pursue this subject further at present, for it belongs, as ethical, to another part of this work. In the meantime, I only wish to point out here that the phenomenon of the will which in itself is uncaused, is yet as such subordinated to the law of necessity, that is, the principle of sufficient reason, so that in the necessity with which the phenomena of nature follow each other, we may find nothing to hinder us from recognising in them the manifestations of will.

Only those changes which have no other ground than a motive, i.e., an idea, have hitherto been regarded as manifestations of will. Therefore in nature a will has only been attributed to man, or at the most to animals; for knowledge, the idea, is of course, as I have said elsewhere, the true and exclusive characteristic of [pg 148] animal life. But that the will is also active where no knowledge guides it, we see at once in the instinct and the mechanical skill of animals.31 That they have ideas and knowledge is here not to the point, for the end towards which they strive as definitely as if it were a known motive, is yet entirely unknown to them. Therefore in such cases their action takes place without motive, is not guided by the idea, and shows us first and most distinctly how the will may be active entirely without knowledge. The bird of a year old has no idea of the eggs for which it builds a nest; the young spider has no idea of the prey for which it spins a web; nor has the ant-lion any idea of the ants for which he digs a trench for the first time. The larva of the stag-beetle makes the hole in the wood, in which it is to await its metamorphosis, twice as big if it is going to be a male beetle as if it is going to be a female, so that if it is a male there may be room for the horns, of which, however, it has no idea. In such actions of these creatures the will is clearly operative as in their other actions, but it is in blind activity, which is indeed accompanied by knowledge but not guided by it. If now we have once gained insight into the fact, that idea as motive is not a necessary and essential condition of the activity of the will, we shall more easily recognise the activity of will where it is less apparent. For example, we shall see that the house of the snail is no more made by a will which is foreign to the snail itself, than the house which we build is produced through another will than our own; but we shall recognise in both houses the work of a will which objectifies itself in both the phenomena—a will which works in us according to motives, but in the snail still blindly as formative impulse directed outwards. In us also the same will is in many ways only blindly active: in all the functions of our body which are not guided by knowledge, in all its vital and vegetative processes, [pg 149] digestion, circulation, secretion, growth, reproduction. Not only the actions of the body, but the whole body itself is, as we have shown above, phenomenon of the will, objectified will, concrete will. All that goes on in it must therefore proceed through will, although here this will is not guided by knowledge, but acts blindly according to causes, which in this case are called stimuli.

I call a cause, in the narrowest sense of the word, that state of matter, which, while it introduces another state with necessity, yet suffers just as great a change itself as that which it causes; which is expressed in the rule, “action and reaction are equal.” Further, in the case of what is properly speaking a cause, the effect increases directly in proportion to the cause, and therefore also the reaction. So that, if once the mode of operation be known, the degree of the effect may be measured and calculated from the degree of the intensity of the cause; and conversely the degree of the intensity of the cause may be calculated from the degree of the effect. Such causes, properly so called, operate in all the phenomena of mechanics, chemistry, and so forth; in short, in all the changes of unorganised bodies. On the other hand, I call a stimulus, such a cause as sustains no reaction proportional to its effect, and the intensity of which does not vary directly in proportion to the intensity of its effect, so that the effect cannot be measured by it. On the contrary, a small increase of the stimulus may cause a very great increase of the effect, or conversely, it may eliminate the previous effect altogether, and so forth. All effects upon organised bodies as such are of this kind. All properly organic and vegetative changes of the animal body must therefore be referred to stimuli, not to mere causes. But the stimulus, like every cause and motive generally, never determines more than the point of time and space at [pg 150] which the manifestation of every force is to take place, and does not determine the inner nature of the force itself which is manifested. This inner nature we know, from our previous investigation, is will, to which therefore we ascribe both the unconscious and the conscious changes of the body. The stimulus holds the mean, forms the transition between the motive, which is causality accompanied throughout by knowledge, and the cause in the narrowest sense. In particular cases it is sometimes nearer a motive, sometimes nearer a cause, but yet it can always be distinguished from both. Thus, for example, the rising of the sap in a plant follows upon stimuli, and cannot be explained from mere causes, according to the laws of hydraulics or capillary attraction; yet it is certainly assisted by these, and altogether approaches very near to a purely causal change. On the other hand, the movements of the Hedysarum gyrans and the Mimosa pudica, although still following upon mere stimuli, are yet very like movements which follow upon motives, and seem almost to wish to make the transition. The contraction 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, [pg 151] 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, [pg 152] 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 [pg 153] 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 [pg 154] 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 [pg 155] 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? And what would they be in this sense? What is that other side of them which is toto genere different from idea? What is the thing-in-itself? The will, we have answered, but for the present I set that answer aside.

Whatever the thing-in-itself may be, Kant is right in his conclusion that time, space, and causality (which we afterwards found to be forms of the principle of sufficient reason, the general expression of the forms of the phenomenon) are not its properties, but come to it only after, and so far as, it has become idea. That is, they belong only to its phenomenal existence, not to itself. For since the subject fully understands and constructs them out of itself, independently of all object, they must be dependent upon existence as idea as such, not upon that which becomes idea. They must be the form of the idea as such; but not qualities of that which has assumed this form. They must be already given with the mere antithesis of subject [pg 156] and object (not as concepts but as facts), and consequently they must be only the more exact determination of the form of knowledge in general, whose most universal determination is that antithesis itself. Now, that in the phenomenon, in the object, which is in its turn conditioned by time, space and causality, inasmuch as it can only become idea by means of them, namely multiplicity, through co-existence and succession, change and permanence through the law of causality, matter which can only become idea under the presupposition of causality, and lastly, all that becomes idea only by means of these,—all this, I say, as a whole, does not in reality belong to that which appears, to that which has passed into the form of idea, but belongs merely to this form itself. And conversely, that in the phenomenon which is not conditioned through time, space and causality, and which cannot be referred to them, nor explained in accordance with them, is precisely that in which the thing manifested, the thing-in-itself, directly reveals itself. It follows from this that the most complete capacity for being known, that is to say, the greatest clearness, distinctness, and susceptibility of exhaustive explanation, will necessarily belong to that which pertains to knowledge as such, and thus to the form of knowledge; but not to that which in itself is not idea, not object, but which has become knowledge only through entering these forms; in other words, has become idea, object. Thus only that which depends entirely upon being an object of knowledge, upon existing as idea in general and as such (not upon that which becomes known, and has only become idea), which therefore belongs without distinction to everything that is known, and which, on that account, is found just as well if we start from the subject as if we start from the object,—this alone can afford us without reserve a sufficient, exhaustive knowledge, a knowledge which is clear to the very foundation. But this consists of nothing but those forms of all phenomena of which we are conscious [pg 157] a priori, and which may be generally expressed as the principle of sufficient reason. Now, the forms of this principle which occur in knowledge of perception (with which alone we are here concerned) are time, space, and causality. The whole of pure mathematics and pure natural science a priori is based entirely upon these. Therefore it is only in these sciences that knowledge finds no obscurity, does not rest upon what is incomprehensible (groundless, i.e., will), upon what cannot be further deduced. It is on this account that Kant wanted, as we have said, to apply the name science specially and even exclusively to these branches of knowledge together with logic. But, on the other hand, these branches of knowledge show us nothing more than mere connections, relations of one idea to another, form devoid of all content. All content which they receive, every phenomenon which fills these forms, contains something which is no longer completely knowable in its whole nature, something which can no longer be entirely explained through something else, something then which is groundless, through which consequently the knowledge loses its evidence and ceases to be completely lucid. This that withholds itself from investigation, however, is the thing-in-itself, is that which is essentially not idea, not object of knowledge, but has only become knowable by entering that form. The form is originally foreign to it, and the thing-in-itself can never become entirely one with it, can never be referred to mere form, and, since this form is the principle of sufficient reason, can never be completely explained. If therefore all mathematics affords us an exhaustive knowledge of that which in the phenomena is quantity, position, number, in a word, spatial and temporal relations; if all etiology gives us a complete account of the regular conditions under which phenomena, with all their determinations, appear in time and space, but, with it all, teaches us nothing more than why in each case this particular phenomenon must appear [pg 158] just at this time here, and at this place now; it is clear that with their assistance we can never penetrate to the inner nature of things. There always remains something which no explanation can venture to attack, but which it always presupposes; the forces of nature, the definite mode of operation of things, the quality and character of every phenomenon, that which is without ground, that which does not depend upon the form of the phenomenal, the principle of sufficient reason, but is something to which this form in itself is foreign, something which has yet entered this form, and now appears according to its law, a law, however, which only determines the appearance, not that which appears, only the how, not the what, only the form, not the content. Mechanics, physics, and chemistry teach the rules and laws according to which the forces of impenetrability, gravitation, rigidity, fluidity, cohesion, elasticity, heat, light, affinity, magnetism, electricity, &c., operate; that is to say, the law, the rule which these forces observe whenever they enter time and space. But do what we will, the forces themselves remain qualitates occultæ. For it is just the thing-in-itself, which, because it is manifested, exhibits these phenomena, which are entirely different from itself. In its manifestation, indeed, it is completely subordinated to the principle of sufficient reason as the form of the idea, but it can never itself be referred to this form, and therefore cannot be fully explained etiologically, can never be completely fathomed. It is certainly perfectly comprehensible so far as it has assumed that form, that is, so far as it is phenomenon, but its inner nature is not in the least explained by the fact that it can thus be comprehended. Therefore the more necessity any knowledge carries with it, the more there is in it of that which cannot be otherwise thought or presented in perception—as, for example, space-relations—the clearer and more sufficing then it is, the less pure objective content it has, or the less reality, properly so called, is [pg 159] given in it. And conversely, the more there is in it which must be conceived as mere chance, and the more it impresses us as given merely empirically, the more proper objectivity and true reality is there in such knowledge, and at the same time, the more that is inexplicable, that is, that cannot be deduced from anything else.

It is true that at all times an etiology, unmindful of its real aim, has striven to reduce all organised life to chemism or electricity; all chemism, that is to say quality, again to mechanism (action determined by the shape of the atom), this again sometimes to the object of phoronomy, i.e., the combination of time and space, which makes motion possible, sometimes to the object of mere geometry, i.e., position in space (much in the same way as we rightly deduce the diminution of an effect from the square of the distance, and the theory of the lever in a purely geometrical manner): geometry may finally be reduced to arithmetic, which, on account of its one dimension, is of all the forms of the principle of sufficient reason, the most intelligible, comprehensible, and completely susceptible of investigation. As instances of the method generally indicated here, we may refer to the atoms of Democritus, the vortex of Descartes, the mechanical physics of Lesage, which towards the end of last century tried to explain both chemical affinities and gravitation mechanically by impact and pressure, as may be seen in detail in “Lucrèce Neutonien;” Reil's form and combination as the cause of animal life, also tends in this direction. Finally, the crude materialism which even now in the middle of the nineteenth century has been served up again under the ignorant delusion that it is original, belongs distinctly to this class. It stupidly denies vital force, and first of all tries to explain the phenomena of life from physical and chemical forces, and those again from the mechanical effects of the matter, position, form, and motion of imagined atoms, and thus [pg 160] seeks to reduce all the forces of nature to action and reaction as its thing-in-itself. According to this teaching, light is the mechanical vibration or undulation of an imaginary ether, postulated for this end. This ether, if it reaches the eye, beats rapidly upon the retina, and gives us the knowledge of colour. Thus, for example, four hundred and eighty-three billion beats in a second give red, and seven hundred and twenty-seven billion beats in a second give violet. Upon this theory, persons who are colour-blind must be those who are unable to count the beats, must they not? Such crass, mechanical, clumsy, and certainly knotty theories, which remind one of Democritus, are quite worthy of those who, fifty years after the appearance of Goethe's doctrine of colour, still believe in Newton's homogeneous light, and are not ashamed to say so. They will find that what is overlooked in the child (Democritus) will not be forgiven to the man. They might indeed, some day, come to an ignominious end; but then every one would slink away and pretend that he never had anything to do with them. We shall soon have to speak again of this false reduction of the forces of nature to each other; so much for the present. Supposing this theory were possible, all would certainly be explained and established and finally reduced to an arithmetical problem, which would then be the holiest thing in the temple of wisdom, to which the principle of sufficient reason would at last have happily conducted us. But all content of the phenomenon would have disappeared, and the mere form would remain. The “what appears” would be referred to the “how it appears,” and this “how” would be what is a priori knowable, therefore entirely dependent on the subject, therefore only for the subject, therefore, lastly, mere phantom, idea and form of idea, through and through: no thing-in-itself could be demanded. Supposing, then, that this were possible, the whole world would be derived from the subject, and in fact, that would be accomplished which [pg 161] Fichte wanted to seem to accomplish by his empty bombast. But it is not possible: phantasies, sophisms, castles in the air, have been constructed in this way, but science never. The many and multifarious phenomena in nature have been successfully referred to particular original forces, and as often as this has been done, a real advance has been made. Several forces and qualities, which were at first regarded as different, have been derived from each other, and thus their number has been curtailed. (For example, magnetism from electricity.) Etiology will have reached its goal when it has recognised and exhibited as such all the original forces of nature, and established their mode of operation, i.e., the law according to which, under the guidance of causality, their phenomena appear in time and space, and determine their position with regard to each other. But certain original forces will always remain over; there will always remain as an insoluble residuum a content of phenomena which cannot be referred to their form, and thus cannot be explained from something else in accordance with the principle of sufficient reason. For in everything in nature there is something of which no ground can ever be assigned, of which no explanation is possible, and no ulterior cause is to be sought. This is the specific nature of its action, i.e., the nature of its existence, its being. Of each particular effect of the thing a cause may be certainly indicated, from which it follows that it must act just at this time and in this place; but no cause can ever be found from which it follows that a thing acts in general, and precisely in the way it does. If it has no other qualities, if it is merely a mote in a sunbeam, it yet exhibits this unfathomable something, at least as weight and impenetrability. But this, I say, is to the mote what his will is to a man; and, like the human will, it is, according to its inner nature, not subject to explanation; nay, more—it is in itself identical with this will. It is true that a motive may be given for every manifestation [pg 162] of will, for every act of will at a particular time and in a particular place, upon which it must necessarily follow, under the presupposition of the character of the man. But no reason can ever be given that the man has this character; that he wills at all; that, of several motives, just this one and no other, or indeed that any motive at all, moves his will. That which in the case of man is the unfathomable character which is presupposed in every explanation of his actions from motives is, in the case of every unorganised body, its definitive quality—the mode of its action, the manifestations of which are occasioned by impressions from without, while it itself, on the contrary, is determined by nothing outside itself, and thus is also inexplicable. Its particular manifestations, through which alone it becomes visible, are subordinated to the principle of sufficient reason; it itself is groundless. This was in substance rightly understood by the schoolmen, who called it forma substantialis. (Cf. Suarez, Disput. Metaph., disp. xv. sect. 1.)

It is a greater and a commoner error that the phenomena which we best understand are those which are of most frequent occurrence, and which are most universal and simple; for, on the contrary, these are just the phenomena that we are most accustomed to see about us, and to be ignorant of. It is just as inexplicable to us that a stone should fall to the earth as that an animal should move itself. It has been supposed, as we have remarked above, that, starting from the most universal forces of nature (gravitation, cohesion, impenetrability), it was possible to explain from them the rarer forces, which only operate under a combination of circumstances (for example, chemical quality, electricity, magnetism), and, lastly, from these to understand the organism and the life of animals, and even the nature of human knowing and willing. Men resigned themselves without a word to starting from mere qualitates occultæ, the elucidation of which was entirely given up, for they intended to build [pg 163] upon them, not to investigate them. Such an intention cannot, as we have already said, be carried out. But apart from this, such structures would always stand in the air. What is the use of explanations which ultimately refer us to something which is quite as unknown as the problem with which we started? Do we in the end understand more of the inner nature of these universal natural forces than of the inner nature of an animal? Is not the one as much a sealed book to us as the other? Unfathomable because it is without ground, because it is the content, that which the phenomenon is, and which can never be referred to the form, to the how, to the principle of sufficient reason. But we, who have in view not etiology but philosophy, that is, not relative but unconditioned knowledge of the real nature of the world, take the opposite course, and start from that which is immediately and most completely known to us, and fully and entirely trusted by us—that which lies nearest to us, in order to understand that which is known to us only at a distance, one-sidedly and indirectly. From the most powerful, most significant, and most distinct phenomenon we seek to arrive at an understanding of those that are less complete and weaker. With the exception of my own body, all things are known to me only on one side, that of the idea. Their inner nature remains hidden from me and a profound secret, even if I know all the causes from which their changes follow. Only by comparison with that which goes on in me if my body performs an action when I am influenced by a motive—only by comparison, I say, with what is the inner nature of my own changes determined by external reasons, can I obtain insight into the way in which these lifeless bodies change under the influence of causes, and so understand what is their inner nature. For the knowledge of the causes of the manifestation of this inner nature affords me merely the rule of its appearance in time and space, and nothing more. I can make this comparison because [pg 164] my body is the only object of which I know not merely the one side, that of the idea, but also the other side which is called will. Thus, instead of believing that I would better understand my own organisation, and then my own knowing and willing, and my movements following upon motives, if I could only refer them to movements due to electrical, chemical, and mechanical causes, I must, seeing that I seek philosophy and not etiology, learn to understand from my own movements following upon motives the inner nature of the simplest and commonest movements of an unorganised body which I see following upon causes. I must recognise the inscrutable forces which manifest themselves in all natural bodies as identical in kind with that which in me is the will, and as differing from it only in degree. That is to say, the fourth class of ideas given in the Essay on the Principle of Sufficient Reason must be the key to the knowledge of the inner nature of the first class, and by means of the law of motivation I must come to understand the inner meaning of the law of causation.

Spinoza (Epist. 62) says that if a stone which has been projected through the air had consciousness, it would believe that it was moving of its own will. I add to this only that the stone would be right. The impulse given it is for the stone what the motive is for me, and what in the case of the stone appears as cohesion, gravitation, rigidity, is in its inner nature the same as that which I recognise in myself as will, and what the stone also, if knowledge were given to it, would recognise as will. In the passage referred to, Spinoza had in view the necessity with which the stone flies, and he rightly desires to transfer this necessity to that of the particular act of will of a person. I, on the other hand, consider the inner being, which alone imparts meaning and validity to all real necessity (i.e., effect following upon a cause) as its presupposition. In the case of men this is called character; in the case of a stone it is called quality, but it is [pg 165] the same in both. When it is immediately known it is called will. In the stone it has the weakest, and in man the strongest degree of visibility, of objectivity. St. Augustine recognises, with a true instinct, this identity of the tendencies of all things with our own willing, and I cannot refrain from quoting his naïve account of the matter:—“Si pecora essemus, carnalem vitam et quod secundum sensum ejusdem est amaremus, idque esset sufficiens bonum nostrum, et secundum hoc si esset nobis bene, nihil aliud quæreremus. Item, si arbores essemus, nihil quidem sentientes motu amare possemus: verumtamen id quasi appetere videremur, quo feracius essemus, uberiusque fructuosæ. Si essemus lapides, aut fluctus, aut ventus, aut flamma, vel quid ejusmodi, sine ullo quidem sensu atque vita, non tamen nobis deesset quasi quidam nostrorum locorum atque ordinis appetitus. Nam velut amores corporum momenta sunt ponderum, sive deorsum gravitate, sive sursum levitate nitantur: ita enim corpus pondere, sicut animus amore fertur quocunque fertur” (De Civ. Dei, xi. 28).

It ought further to be mentioned that Euler saw that the inner nature of gravitation must ultimately be referred to an “inclination and desire” (thus will) peculiar to material bodies (in the 68th letter to the Princess). Indeed, it is just this that makes him averse to the conception of gravitation as it existed for Newton, and he is inclined to try a modification of it in accordance with the earlier Cartesian theory, and so to derive gravitation from the impact of an ether upon the bodies, as being “more rational and more suitable for persons who like clear and intelligible principles.” He wishes to banish attraction from physics as a qualitas occulta. This is only in keeping with the dead view of nature which prevailed at Euler's time as the correlative of the immaterial soul. It is only worth noticing because of its bearing upon the fundamental truth established by me, which even at that time this fine intellect saw glimmering in the distance. He hastened to turn in time, and then, in his anxiety at [pg 166] seeing all the prevalent fundamental views endangered, he sought safety in the old and already exploded absurdities.

We know that multiplicity in general is necessarily conditioned by space and time, and is only thinkable in them. In this respect they are called the principium individuationis. But we have found that space and time are forms of the principle of sufficient reason. In this principle all our knowledge a priori is expressed, but, as we showed above, this a priori knowledge, as such, only applies to the knowableness of things, not to the things themselves, i.e., it is only our form of knowledge, it is not a property of the thing-in-itself. The thing-in-itself is, as such, free from all forms of knowledge, even the most universal, that of being an object for the subject. In other words, the thing-in-itself is something altogether different from the idea. If, now, this thing-in-itself is the will, as I believe I have fully and convincingly proved it to be, then, regarded as such and apart from its manifestation, it lies outside time and space, and therefore knows no multiplicity, and is consequently one. Yet, as I have said, it is not one in the sense in which an individual or a concept is one, but as something to which the condition of the possibility of multiplicity, the principium individuationis, is foreign. The multiplicity of things in space and time, which collectively constitute the objectification of will, does not affect the will itself, which remains indivisible notwithstanding it. It is not the case that, in some way or other, a smaller part of will is in the stone and a larger part in the man, for the relation of part and whole belongs exclusively to space, and has no longer any meaning when we go beyond this form of intuition or perception. The more and the less have application only to the phenomenon of will, that is, its visibility, its objectification. Of this there is a higher grade in the plant than in the stone; in the animal a higher grade than in the plant: indeed, the passage of will into visibility, its [pg 167] objectification, has grades as innumerable as exist between the dimmest twilight and the brightest sunshine, the loudest sound and the faintest echo. We shall return later to the consideration of these grades of visibility which belong to the objectification of the will, to the reflection of its nature. But as the grades of its objectification do not directly concern the will itself, still less is it concerned by the multiplicity of the phenomena of these different grades, i.e., the multitude of individuals of each form, or the particular manifestations of each force. For this multiplicity is directly conditioned by time and space, into which the will itself never enters. The will reveals itself as completely and as much in one oak as in millions. Their number and multiplication in space and time has no meaning with regard to it, but only with regard to the multiplicity of individuals who know in space and time, and who are themselves multiplied and dispersed in these. The multiplicity of these individuals itself belongs not to the will, but only to its manifestation. We may therefore say that if, per impossibile, a single real existence, even the most insignificant, were to be entirely annihilated, the whole world would necessarily perish with it. The great mystic Angelus Silesius feels this when he says—