4. THE WORLD AS PERCEPT
4.0 Reactive Thinking
 THE products of thinking are concepts and ideas. What a concept is cannot be expressed in words. Words can do no more than draw our attention to the fact that we have concepts. When someone perceives a tree, the perception acts as a stimulus for thought. Thus an ideal element is added to the perceived object, and the perceiver regards the object and its ideal complement as belonging together. When the object disappears from the field of his perception, the ideal counterpart alone remains. This latter is the concept of the object. The wider the range of our experience, the larger becomes the number of our concepts. Moreover, concepts are not by any means found in isolation one from the other. They combine to form an ordered and systematic whole. The concept "organism," e.g., combines with those of "development according to law," "growth," and others. Other concepts based on particular objects fuse completely with one another. All concepts formed from particular lions fuse in the universal concept "lion." In this way, all the separate concepts combine to form a closed, conceptual system within which each has its special place. Ideas do not differ qualitatively from concepts. They are but fuller, more saturated, more comprehensive concepts. I attach special importance to the necessity of bearing in mind, here, that I make thought my starting-point, and not concepts and ideas which are first gained by means of thought. These latter presuppose thought. My remarks regarding the self-dependent, self-sufficient character of thought cannot, therefore, be simply transferred to concepts. (I make special mention of this, because it is here that I differ from Hegel, who regards the concept as something primary and ultimate.)
 Concepts cannot be derived from perception. This is apparent from the fact that, as man grows up, he slowly and gradually builds up the concepts corresponding to the objects which surround him. Concepts are added to perception.
4.1 Conceptual Search
 A philosopher, widely read at the present day (Herbert Spencer), describes the mental process which we perform upon perception as follows:
 "If, when walking through the fields some day in September, you hear a rustle a few yards in advance, and on observing the ditch-side where it occurs, see the herbage agitated, you will probably turn towards the spot to learn by what this sound and motion are produced. As you approach there flutters into the ditch a partridge; on seeing which your curiosity is satisfied—you have what you call an explanation of the appearances. The explanation, mark, amounts to this—that whereas throughout life you have had countless experiences of disturbance among small stationary bodies, accompanying the movement of other bodies among them, and have generalized the relation between such disturbances and such movements, you consider this particular disturbance explained on finding it to present an instance of the like relation" (First Principles, Part I, par. 23).
A closer analysis leads to a very different description from that here given. When I hear a noise, my first demand is for the concept which fits this percept. Without this concept, the noise is to me a mere noise. Whoever does not reflect further, hears just the noise and is satisfied with that. But my thought makes it clear to me that the noise is to be regarded as an effect. Thus it is only when I combine the concept of effect with the percept of a noise that I am led to go beyond the particular percept and seek for its cause. The concept of "effect" calls up that of "cause," and my next step is to look for the agent, which I find, say, in a partridge. But these concepts, cause and effect, can never be gained through mere perception, however many instances we bring under review. Perception evokes thought, and it is this which shows me how to link separate experiences together.
 If one demands of a "strictly objective science" that it should take its data from perception alone, one must demand also that it abandon all thought. For thought, by its very nature, transcends the objects of perception.
4.2 Conceptual Reference
 It is time now to pass from thought to the thinker. For it is through the thinker that thought and perception are combined. The human mind is the stage on which concept and percept meet and are linked to one another. In saying this, we already characterize this (human) consciousness. It mediates between thought and perception. In perception the object appears as given, in thought the mind seems to itself to be active. It regards the thing as object and itself as the thinking subject. When thought is directed upon the perceptual world we have consciousness of objects; when it is directed upon itself we have self-consciousness. Human consciousness must, of necessity, be at the same time self-consciousness, because it is a consciousness which thinks. For, when thought contemplates its own activity it makes an object for study of its own essential nature, it makes an object of itself as subject.
 It is important to note here that it is only by means of thinking that I am able to determine myself as subject and contrast myself with objects. Therefore thinking must never be regarded as a merely subjective activity. Thinking transcends the distinction of subject and object. It produces these two concepts just as it produces all others. When, therefore, I, as thinking subject, refer a concept to an object, we must not regard this reference as something purely subjective. It is not the subject, but thought, which makes the reference. The subject does not think because it is a subject, rather it conceives itself to be a subject because it can think. The activity of consciousness, in so far as it thinks, is thus not merely subjective. Rather it is neither subjective nor objective; it transcends both these concepts. I ought never to say that I, as an individual subject, think, but rather that I, as subject, exist myself by the grace of thought. Thought thus takes me out of myself and relates me to objects. At the same time it separates me from them, inasmuch as I, as subject, am set over against the objects.
 It is just this which constitutes the double nature of man. His thought embraces himself and the rest of the world. But by this same act of thought he determines himself also as an individual, in contrast with the objective world.
4.3 Conceptual Relationship
 We must next ask ourselves how the other element, which we have so far simply called the perceptual object and which comes, in consciousness, into contact with thought, enters into thought at all?
 In order to answer this question, we must eliminate from the field of consciousness everything which has been imported by thought. For, at any moment, the content of consciousness is always shot through with concepts in the most various ways.
 Let us assume that a being with fully developed human intelligence originated out of nothing and confronted the world. All that it there perceived before its thought began to act would be the pure content of perception. The world so far would appear to this being as a mere chaotic aggregate of sense-data, colors, sounds, sensations of pressure, of warmth, of taste, of smell, and, lastly, feelings of pleasure and pain. This mass constitutes the world of pure unthinking perception. Over against it stands thought, ready to begin its activity as soon as it can find a point of attack. Experience shows that the opportunity is not long in coming. Thought is able to draw threads from one sense-datum to another. It brings definite concepts to bear on these data and thus establishes a relation between them. We have seen above how a noise which we hear is connected with another content by our identifying the first as the effect of the second.
 If now we recollect that the activity of thought is on no account to be considered as merely subjective, then we shall not be tempted to believe that the relations thus established by thought have merely subjective validity.
4.4 Correction Of My Picture Of World
 Our next task is to discover by means of thought what relation the above mentioned immediate sense-data have to the conscious subject.
 The ambiguity of current speech makes it advisable for me to come to an agreement with my readers concerning the meaning of a word which I shall have to employ in what follows. I shall apply the name "percepts" to the immediate sense-data enumerated above, in so far as the subject consciously apprehends them. It is, then, not the process of perception, but the object of this process which I call the "percept."
 I reject the term "sensation," because this has a definite meaning in Physiology which is narrower than that of my term "percept." I can speak of feeling as a percept, but not as a sensation in the physiological sense of the term. Before I can have cognizance of my feeling it must become a percept for me. The manner in which, through observation, we gain knowledge of our thought-processes is such that when we first begin to notice thought, it too may be called a percept.
 The unreflective man regards his percepts, such as they appear to his immediate apprehension, as things having a wholly independent existence. When he sees a tree he believes that it stands in the form which he sees, with the colors of all its parts, etc., there on the spot towards which his gaze is directed. When the same man sees the sun in the morning appear as a disc on the horizon, and follows the course of this disc, he believes that the phenomenon exists and occurs (by itself) exactly as he perceives it. To this belief he clings until he meets with further percepts which contradict his former ones. The child who has as yet had no experience of distance grasps at the moon, and does not correct its first impression as to the real distance until a second percept contradicts the first. Every extension of the circle of my percepts compels me to correct my picture of the world. We see this in everyday life, as well as in the mental development of mankind. The picture which the ancients made for themselves of the relation of the earth to the sun and other heavenly bodies, had to be replaced by another when Copernicus found that it contradicted percepts which in those early days were unknown. A man who had been born blind said, when operated on by Dr. Franz, that the idea of the size of objects which he had formed before his operation by his sense of touch was a very different one. He had to correct his tactual percepts by his visual percepts.
4.5 Mathematical And Qualitative Percept-Picture
 How is it that we are compelled to make these continual corrections in our observations?
 A single reflection supplies the answer to this question. When I stand at one end of an avenue, the trees at the other end, away from me, seem smaller and nearer together than those where I stand. But the scene which I perceive changes when I change the place from which I am looking. The exact form in which it presents itself to me is, therefore, dependent on a condition which inheres, not in the object, but in me, the percipient. It is all the same to the avenue where I stand. But the picture of it which I receive depends essentially on my standpoint. In the same way, it makes no difference to the sun and the planetary system that human beings happen to perceive them from the earth; but the picture of the heavens which human beings have is determined by the fact that they inhabit the earth. This dependence of our percepts on our points of observation is the easiest kind of dependence to understand. The matter becomes more difficult when we realize further that our perceptual world is dependent on our bodily and mental organization. The physicist teaches us that within the space in which we hear a sound there are vibrations of the air, and that there are vibrations also in the particles of the body which we regard as the cause of the sound. These vibrations are perceived as sounds only if we have normally constructed ears. Without them the whole world would be for us for ever silent. Again, the physiologist teaches us that there are men who perceive nothing of the wonderful display of colors which surrounds us. In their world there are only degrees of light and dark. Others are blind only to one color, e.g., red. Their world lacks this color tone, and hence it is actually a different one from that of the average man. I should like to call the dependence of my perceptual world on my point of observation "mathematical," and its dependence on my organization "qualitative." The former determines proportions of size and mutual distances of my percepts, the latter their quality. The fact that I see a red surface as red—this qualitative determination—depends on the structure of my eye.
4.6 Subjective Percept-Picture
 My percepts, then, are in the first instance subjective. The recognition of the subjective character of our percepts may easily lead us to doubt whether there is any objective basis for them at all. When we know that a percept, e.g., that of a red color or of a certain tone, is not possible without a specific structure of our organism, we may easily be led to believe that it has no being at all apart from our subjective organization, that it has no kind of existence apart from the act of perceiving of which it is the object. The classical representative of this theory is George Berkeley, who held that from the moment we realize the importance of a subject for perception, we are no longer able to believe in the existence of a world apart from a conscious mind.
"Some truths there are so near and obvious to the mind that man need only open his eyes to see them. Such I take this important one to be, viz., that all the choir of heaven and the furniture of the earth—in a word, all those bodies which compose the mighty frame of the world—have not any subsistence without a mind; that their being is to be perceived or known; that consequently, so long as they are not actually perceived by me, or do not exist in my mind or that of any other created spirit, they must either have no existence at all or else subsist in the mind of some Eternal Spirit" (Berkeley, Of the Principles of Human Knowledge, Part I, Section 6).
On this view, when we take away the act of perceiving, nothing remains of the percept. There is no color when none is seen, no sound when none is heard. Extension, form, and motion exist as little as color and sound apart from the act of perception. We never perceive bare extension or shape. These are always joined with color or some other quality, which are undoubtedly dependent on the subject. If these latter disappear when we cease to perceive, the former, being connected with them, must disappear likewise.
 If it is urged that, even though figure, color, sound, etc., have no existence except in the act of perception, yet there must be things which exist apart from perception and which are similar to the percepts in our minds, then the view we have mentioned would answer, that a color can be similar only to a color, a figure to a figure. Our percepts can be similar only to our percepts and to nothing else. Even what we call a thing is nothing but a collection of percepts which are connected in a definite way. If I strip a table of its shape, extension, color, etc.—in short, of all that is merely my percepts—then nothing remains over. If we follow this view to its logical conclusion, we are led to the assertion that the objects of my perceptions exist only through me, and only in as far as, and as long as, I perceive them. They disappear with my perceiving and have no meaning apart from it. Apart from my percepts I know of no objects and cannot know of any.
 No objection can be made to this assertion as long as we take into account merely the general fact that the percept is determined in part by the organization of the subject. The matter would be far otherwise if we were in a position to say what part exactly is played by our perceiving in the occurrence of a percept. We should know then what happens to a percept whilst it is being perceived, and we should also be able to determine what character it must possess before it comes to be perceived.
4.7 Idea: After-effect Of Observation
 This leads us to turn our attention from the object of a perception to the subject of it. I am aware not only of other things but also of myself. The content of my perception of myself consists, in the first instance, in that I am something stable in contrast with the ever coming and going flux of percepts. The awareness of myself accompanies in my consciousness the awareness of all other percepts. When I am absorbed in the perception of a given object I am, for the time being, aware only of this object. Next I become aware also of myself. I am then conscious, not only of the object, but also of my Self as opposed to and observing the object. I do not merely see a tree, I know also that it is I who see it. I know, moreover, that some process takes place in me when I observe a tree. When the tree disappears from my field of vision, an after-effect of this process remains, viz., an image of the tree. This image has become associated with my Self during my perception. My Self has become enriched; to its content a new element has been added. This element I call my idea of the tree. I should never have occasion to talk of ideas, were I not aware of my own Self. Percepts would come and go; I should let them slip by. It is only because I am aware of my Self, and observe that with each perception the content of the Self is changed, that I am compelled to connect the perception of the object with the changes in the content of my Self, and to speak of having an idea.
4.8 Idea: Caused By Unknown Thing-In-Itself
 That I have ideas is in the same sense matter of observation to me as that other objects have color, sound, etc. I am now also able to distinguish these other objects, which stand over against me, by the name of the outer world, whereas the contents of my perception of my Self form my inner world. The failure to recognize the true relation between idea and object has led to the greatest misunderstandings in modern philosophy. The fact that I perceive a change in myself, that my Self undergoes a modification, has been thrust into the foreground, whilst the object which causes these modifications is altogether ignored. In consequence it has been said that we perceive, not objects, but only our ideas. I know, so it is said, nothing of the table in itself, which is the object of my perception, but only of the changes which occur within me when I perceive a table. This theory should not be confused with the Berkeleyan theory mentioned above. Berkeley maintains the subjective nature of my perceptual contents, but he does not say that I can know only my own ideas. He limits my knowledge to my ideas because, on his view, there are no objects other than ideas. What I perceive as a table no longer exists, according to Berkeley, when I cease to look at it. This is why Berkeley holds that our percepts are created directly by the omnipotence of God. I see a table because God causes this percept in me. For Berkeley, therefore, nothing is real except God and human spirits. What we call the "world" exists only in spirits. What the naive man calls the outer world, or material nature, is for Berkeley non-existent. This theory is confronted by the now predominant Kantian view which limits our knowledge of the world to our ideas, not because of any conviction that nothing beyond these ideas exists, but because it holds that we are so organized that we can have knowledge only of the changes within our own selves, not of the things-in-themselves which are the causes of these changes. This view concludes from the fact that I know only my own ideas, not that there is no reality independent of them, but only that the subject cannot have direct knowledge of such reality. The mind can merely "through the medium of its subjective thoughts imagine it, conceive it, know it, or perhaps also fail to know it" (O. Liebmann, Zur Analysis der Wirklichkeit, p. 28). Kantians believe that their principles are absolutely certain, indeed immediately evident, without any proof.
"The most fundamental principle which the philosopher must begin by grasping clearly, consists in the recognition that our knowledge, in the first instance, does not extend beyond our ideas. Our ideas are all that we immediately have and experience, and just because we have immediate experience of them the most radical doubt cannot rob us of this knowledge. On the other hand, the knowledge which transcends my ideas—taking ideas here in the widest possible sense, so as to include all psychical processes—is not proof against doubt. Hence, at the very beginning of all philosophy we must explicitly set down all knowledge which transcends ideas as open to doubt."
4.9 Idea: What My Organization Transmits
These are the opening sentences of Volkelt's book on Kant's Theory of Knowledge. What is here put forward as an immediate and self-evident truth is, in reality, the conclusion of a piece of argument which runs as follows. Naive common sense believes that things, just as we perceive them, exist also outside our minds. Physics, Physiology, and Psychology, however, teach us that our percepts are dependent on our organization, and that therefore we cannot know anything about external objects except what our organization transmits to us. The objects which we perceive are thus modifications of our organization, not things-in-themselves. This line of thought has, in fact, been characterized by Ed. von Hartmann as the one which leads necessarily to the conviction that we can have direct knowledge only of our own ideas (cp. his Grundproblem der Erkenntnistheorie, pp. 16-40).
Because outside our organisms we find vibrations of particles and of air, which are perceived by us as sounds, it is concluded that what we call sound is nothing more than a subjective reaction of our organisms to these motions in the external world. Similarly, color and heat are inferred to be merely modifications of our organisms. And, further, these two kinds of percepts are held to be the effects of processes in the external world which are utterly different from what we experience as heat or as color. When these processes stimulate the nerves in the skin of my body, I perceive heat; when they stimulate the optical nerve I perceive light and color. Light, color, and heat, then, are the reactions of my sensory nerves to external stimuli. Similarly, the sense of touch reveals to me, not the objects of the outer world, but only states of my own body. The physicist holds that bodies are composed of infinitely small particles called molecules, and that these molecules are not in direct contact with one another, but have definite intervals between them. Between them, therefore, is empty space. Across this space they act on one another by attraction and repulsion. If I put my hand on a body, the molecules of my hand by no means touch those of the body directly, but there remains a certain distance between body and hand, and what I experience as the body's resistance is nothing but the effect of the force of repulsion which its molecules exert on my hand. I am absolutely external to the body and experience only its effects on my organism.
 The theory of the so-called Specific Nervous Energy, which has been advanced by J. Muller, supplements these speculations. It asserts that each sense has the peculiarity that it reacts to all external stimuli in only one definite way. If the optic nerve is stimulated, light sensations result, irrespective of whether the stimulation is due to what we call light, or to mechanical pressure, or an electrical current. On the other hand, the same external stimulus applied to different senses gives rise to different sensations. The conclusion from these facts seems to be, that our sense-organs can give us knowledge only of what occurs in themselves, but not of the external world. They determine our percepts, each according to its own nature.
 Physiology shows, further, that there can be no direct knowledge even of the effects which objects produce on our sense-organs. Through his study of the processes which occur in our own bodies, the physiologist finds that, even in the sense-organs, the effects of the external process are modified in the most diverse ways. We can see this most clearly in the case of eye and ear. Both are very complicated organs which modify the external stimulus considerably, before they conduct it to the corresponding nerve. From the peripheral end of the nerve the modified stimulus is then conducted to the brain. Here the central organs must in turn be stimulated. The conclusion is, therefore, drawn that the external process undergoes a series of transformations before it reaches consciousness. The brain processes are connected by so many intermediate links with the external stimuli, that any similarity between them is out of the question. What the brain ultimately transmits to the soul is neither external processes, nor processes in the sense-organs, but only such as occur in the brain. But even these are not apprehended immediately by the soul. What we finally have in consciousness are not brain processes at all, but sensations. My sensation of red has absolutely no similarity with the process which occurs in the brain when I sense red. The sensation, again, occurs as an effect in the mind, and the brain process is only its cause. This is why Hartmann (Grundproblem der Erkenntnistheorie, p. 37) says, "What the subject experiences is therefore only modifications of his own psychical states and nothing else."
However, when I have sensations, they are very far as yet from being grouped in those complexes which I perceive as "things." Only single sensations can be transmitted to me by the brain. The sensations of hardness and softness are transmitted to me by the organ of touch, those of color and light by the organ of sight. Yet all these are found united in one object. This unification must, therefore, be brought about by the soul itself; that is, the soul constructs things out of the separate sensations which the brain conveys to it. My brain conveys to me singly, and by widely different paths, the visual, tactual, and auditory sensations which the soul then combines into the idea of a trumpet. Thus, what is really the result of a process (i.e., the idea of a trumpet), is for my consciousness the primary datum. In this result nothing can any longer be found of what exists outside of me and originally stimulated my sense - organs. The external object is lost entirely on the way to the brain and through the brain to the soul.
4.10 Perceived World Is A Projection Of Soul Qualities
 It would be hard to find in the history of human speculation another edifice of thought which has been built up with greater ingenuity, and which yet, on closer analysis, collapses into nothing. Let us look a little closer at the way it has been constructed. The theory starts with what is given in naive consciousness, i.e., with things as perceived. It proceeds to show that none of the qualities which we find in these things would exist for us, had we no sense-organs. No eye—no color. Therefore, the color is not, as yet, present in the stimulus which affects the eye. It arises first through the interaction of the eye and the object. The latter is, therefore, colorless. But neither is the color in the eye, for in the eye there is only a chemical, or physical, process which is first conducted by the optic nerve to the brain, and there initiates another process. Even this is not yet the color. That is only produced in the soul by means of the brain process. Even then it does not yet appear in consciousness, but is first referred by the soul to a body in the external world. There I finally perceive it, as a quality of this body. We have traveled in a complete circle. We are conscious of a colored object. That is the starting-point. Here thought begins its construction. If I had no eye, the object would be, for me, colorless. I cannot, therefore, attribute the color to the object. I must look for it elsewhere. I look for it, first, in the eye—in vain; in the nerve—in vain; in the brain—in vain once more; in the soul—here I find it indeed, but not attached to the object. I recover the colored body only on returning to my starting-point. The circle is completed. The theory leads me to identify what the naive man regards as existing outside of him, as really a product of my mind.
4.11 External Perception Is Idea
 As long as one stops here everything seems to fit beautifully. But we must go over the argument once more from the beginning. Hitherto I have used, as my starting-point, the object, i.e., the external percept of which up to now, from my naive standpoint, I had a totally wrong conception. I thought that the percept, just as I perceive it, had objective existence. But now I observe that it disappears with my act of perception, that it is only a modification of my mental state. Have I, then, any right at all to start from it in my arguments? Can I say of it that it acts on my soul? I must henceforth treat the table of which formerly I believed that it acted on me, and produced an idea of itself in me, as itself an idea. But from this it follows logically that my sense-organs, and the processes in them are also merely subjective. I have no right to talk of a real eye but only of my idea of an eye. Exactly the same is true of the nerve paths, and the brain processes, and even of the process in the soul itself, through which things are supposed to be constructed out of the chaos of diverse sensations. If assuming the truth of the first circle of argumentation, I run through the steps of my cognitive activity once more, the latter reveals itself as a tissue of ideas which, as such, cannot act on one another. I cannot say that my idea of the object acts on my idea of the eye, and that from this interaction results my idea of color. But it is necessary that I should say this. For as soon as I see clearly that my sense-organs and their activity, my nerve- and soul-processes, can also be known to me only through perception, the argument which I have outlined reveals itself in its full absurdity. It is quite true that I can have no percept without the corresponding sense-organ. But just as little can I be aware of a sense-organ without perception. From the percept of a table I can pass to the eye which sees it, or the nerves in the skin which touches it, but what takes place in these I can, in turn, learn only from perception. And then I soon perceive that there is no trace of similarity between the process which takes place in the eye and the color which I see. I cannot get rid of color sensations by pointing to the process which takes place in the eye whilst I perceive a color. No more can I re-discover the color in the nerve- or brain-processes. I only add a new percept, localized within the organism, to the first percept which the naive man localizes outside of his organism. I only pass from one percept to another.
 Moreover, there is a break in the whole argument. I can follow the processes in my organism up to those in my brain, even though my assumptions become more and more hypothetical as I approach the central processes of the brain. The method of external observation ceases with the process in my brain, more particularly with the process which I should observe, if I could treat the brain with the instruments and methods of Physics and Chemistry. The method of internal observation, or introspection, begins with the sensations, and includes the construction of things out of the material of sense-data. At the point of transition from brain process to sensation, there is a break in the sequence of observation.
 The theory which I have here described, and which calls itself Critical Idealism, in contrast to the standpoint of naive common sense which it calls Naive Realism, makes the mistake of characterizing one group of percepts as ideas, whilst taking another group in the very same sense as the Naive Realism which it apparently refutes. It establishes the ideal character of percepts by accepting naively, as objectively valid facts, the percepts connected with one's own body; and, in addition, it fails to see that it confuses two spheres of observation, between which it can find no connecting link.
4.12 Objective Existence Of Own Organism
 Critical Idealism can refute Naive Realism only by itself assuming, in naive-realistic fashion, that one's own organism has objective existence. As soon as the Idealist realizes that the percepts connected with his own organism stand on exactly the same footing as those which Naive Realism assumes to have objective existence, he can no longer use the former as a safe foundation for his theory. He would, to be consistent, have to regard his own organism also as a mere complex of ideas. But this removes the possibility of regarding the content of the perceptual world as a product of the mind's organization. One would have to assume that the idea "color" was only a modification of the idea "eye." So-called Critical Idealism can be established only by borrowing the assumptions of Naive Realism. The apparent refutation of the latter is achieved only by uncritically accepting its own assumptions as valid in another sphere.
 This much, then, is certain: Analysis within the world of percepts cannot establish Critical Idealism, and, consequently, cannot strip percepts of their objective character.
 Still less is it legitimate to represent the principle that "the perceptual world is my idea" as self-evident and needing no proof. Schopenhauer begins his chief work, The World as Will and Idea, with the words:
"The world is my idea—this is a truth which holds good for everything that lives and knows, though man alone can bring it into reflective and abstract consciousness. If he really does this, he has attained to philosophical wisdom. It then becomes clear and certain to him that what he knows is not a sun and an earth, but only an eye that sees a sun, a hand that feels an earth; that the world which surrounds him is there only in idea, i.e., only in relation to something else, the consciousness which is himself. If any truth can be asserted a priori, it is this: for it is the expression of the most general form of all possible and thinkable experience, a form which is more general than time, or space, or causality, for they all presuppose it. . ." (The World as Will and Idea, Book I, par. I).
This whole theory is wrecked by the fact, already mentioned above, that the eyes and the hand are just as much percepts as the sun and the earth. Using Schopenhauer's vocabulary in his own sense, I might maintain against him that my eye which sees the sun, and my hand which feels the earth, are my ideas just like the sun and the earth themselves. That, put in this way, the whole theory cancels itself, is clear without further argument. For only my real eye and my real hand, but not my ideas "eye" and "hand," could own the ideas "sun" and "earth" as modifications. Yet it is only in terms of these ideas that Critical Idealism has the right to speak.
 Critical Idealism is totally unable to gain an insight unto the relation of percept to idea. It cannot make the separation, mentioned on p. 58, between what happens to the percept in the process of perception and what must be inherent in it prior to perception. We must therefore attempt this problem in another way.
5. OUR KNOWLEDGE OF THE WORLD
5.0 Finding The Concept That Corresponds To The World
 FROM the foregoing considerations it follows that it is impossible to prove, by analysis of the content of our perceptions, that our percepts are ideas. This is supposed to be proved by showing that, if the process of perceiving takes place in the way in which we conceive it in accordance with the naive-realistic assumptions concerning the psychological and physiological constitution of human individuals, then we have to do, not with things themselves, but merely with our ideas of things. Now, if Naive Realism, when consistently thought out, leads to results which directly contradict its presuppositions, then these presuppositions must be discarded as unsuitable for the foundation of a theory of the world. In any case, it is inadmissible to reject the presuppositions and yet accept the consequences, as the Critical Idealist does who bases his assertion that the world is my idea on the line of argument indicated above. (Eduard von Hartmann gives in his work Das Grundproblem der Erkenntnistheorie a full account of this line of argument.)
 The truth of Critical Idealism is one thing, the persuasiveness of its proofs another. How it stands with the former, will appear later in the course of our argument, but the persuasiveness of its proofs is nil. If one builds a house, and the ground floor collapses whilst the first floor is being built, then the first floor collapses too. Naive Realism and Critical Idealism are related to one another like the ground floor to the first floor in this simile.
 For one who holds that the whole perceptual world is only an ideal world, and, moreover, the effect of things unknown to him acting on his soul, the real problem of knowledge is naturally concerned, not with the ideas present only in the soul, but with the things which lie outside his consciousness, and which are independent of him. He asks, How much can we learn about them indirectly, seeing that we cannot observe them directly? From this point of view, he is concerned, not with the connection of his conscious percepts with one another, but with their causes which transcend his consciousness and exist independently of him, whereas the percepts, on his view, disappear as soon as he turns his sense-organs away from the things themselves. Our consciousness, on this view, works like a mirror from which the pictures of definite things disappear the very moment its reflecting surface is not turned towards them. If, now, we do not see the things themselves, but only their reflections, we must obtain knowledge of the nature of the former indirectly by drawing conclusions from the character of the latter. The whole of modern science adopts this point of view, when it uses percepts only as a means of obtaining information about the motions of matter which lie behind them, and which alone really "are." If the philosopher, as Critical Idealist, admits real existence at all, then his sole aim is to gain knowledge of this real existence indirectly by means of his ideas. His interest ignores the subjective world of ideas, and pursues instead the causes of these ideas.
 The Critical Idealist can, however, go even further and say, I am confined to the world of my own ideas and cannot escape from it. If I conceive a thing beyond my ideas, this concept, once more, is nothing but my idea. An Idealist of this type will either deny the thing-in-itself entirely or, at any rate, assert that it has no significance for human minds, i.e., that it is as good as non-existent since we can know nothing of it.
 To this kind of Critical Idealist the whole world seems a chaotic dream, in the face of which all striving for knowledge is simply meaningless. For him there can be only two sorts of men: (1) victims of the illusion that the dreams they have woven themselves are real things, and (2) wise men who see through the nothingness of this dream world, and who gradually lose all desire to trouble themselves further about it. From this point of view, even one's own personality may become a mere dream phantom. Just as during sleep there appears among my dream-images an image of myself, so in waking consciousness the idea of my own Self is added to the idea of the outer world. I have then given to me in consciousness, not my real Self, but only my idea of my Self. Whoever denies that things exist, or, at least, that we can know anything of them, must also deny the existence, respectively the knowledge, of one's own personality. This is how the Critical Idealist comes to maintain that "All reality transforms itself into a wonderful dream, without a life which is the object of the dream, and without a mind which has the dream; into a dream which is nothing but a dream of itself." (Cp. Fichte, Die Bestimmung des Menschen.)
 Whether he who believes that he recognizes immediate experience to be a dream, postulates nothing behind this dream, or whether he relates his ideas to actual things, is immaterial. In both cases life itself must lose all scientific interest for him. However, whereas for those who believe that the whole of accessible reality is exhausted in dreams, all science is an absurdity, for those who feel compelled to argue from ideas to things, science consists in studying these things-in-themselves. The first of these theories of the world may be called Absolute Illusionism, the second is called Transcendental Realism* by its most rigorously logical exponent, Eduard von Hartmann.
 These two points of view have this in common with Naive Realism, that they seek to gain a footing in the world by means of an analysis of percepts. Within this sphere, however, they are unable to find any stable point.
5.1 The Awakened State Of Thinking
 One of the most important questions for an adherent of Transcendental Realism would have to be, how the Ego constructs the world of ideas out of itself. A world of ideas which was given to us, and which disappeared as soon as we shut our senses to the external world, might provoke an earnest desire for knowledge, in so far as it was a means for investigating indirectly the world of the self-existing Self. If the things of our experience were "ideas," then our everyday life would be like a dream, and the discovery of the true facts like waking. Even our dream-images interest us as long as we dream and, consequently, do not detect their dream character. But as soon as we wake, we no longer look for the connections of our dream-images among themselves, but rather for the physical, physiological, and psychological processes which underlie them. In the same way, a philosopher who holds the world to be his idea, cannot be interested in the reciprocal relations of the details within the world. If he admits the existence of a real Ego at all, then his question will be, not how one of his ideas is associated with another, but what takes place in the Soul which is independent of these ideas, while a certain train of ideas passes through his consciousness. If I dream that I am drinking wine which makes my throat burn, and then wake up with a fit of coughing (cp. Weygandt, Entstehung der Traume, 1893) I cease, the moment I wake, to be interested in the dream-experience for its own sake. My attention is now concerned only with the physiological and psychological processes by means of which the irritation which causes me to cough, comes to be symbolically expressed in the dream. Similarly, once the philosopher is convinced that the given world consists of nothing but ideas, his interest is bound to switch from them at once to the soul which is the reality lying behind them. The matter is more serious, however, for the Illusionist who denies the existence of an Ego behind the "ideas," or at least holds this Ego to be unknowable. We might very easily be led to such a view by the reflection that, in contrast to dreaming, there is the waking state in which we have the opportunity to detect our dreams, and to realize the real relations of things, but that there is no state of the self which is related similarly to our waking conscious life. Every adherent of this view fails entirely to see that there is, in fact, something which is to mere perception what our waking experience is to our dreams. This something is thought.
5.2 Thought That Applies To The World
 The naive man cannot be charged with failure to perceive this. He accepts life as it is, and regards things as real just as they present themselves to him in experience. The first step, however, which we take beyond this standpoint can be only this, that we ask how thought is related to perception. It makes no difference whether or no the percept, as given to me, has a continuous existence before and after I perceive it. If I want to assert anything whatever about it, I can do so only with the help of thought. When I assert that the world is my idea, I have enunciated the result of an act of thought, and if my thought is not applicable to the world, then my result is false. Between a percept and every kind of judgment about it there intervenes thought.
5.3 World Connects With Corresponding Concept
 The reason why, in our discussion about things, we generally overlook the part played by thought, has already been given above (p. 31). It lies in the fact that our attention is concentrated only on the object about which we think, but not at the same time on the thinking itself. The naive mind, therefore, treats thought as something which has nothing to do with things, but stands altogether aloof from them and makes its theories about them. The theory which the thinker constructs concerning the phenomena of the world is regarded, not as part of the real things, but as existing only in men's heads. The world is complete in itself even without this theory. It is all ready-made and finished with all its substances and forces, and of this ready-made world man makes himself a picture. Whoever thinks thus need only be asked one question. What right have you to declare the world to be complete without thought? Does not the world cause thoughts in the minds of men with the same necessity as it causes the blossoms on plants? Plant a seed in the earth. It puts forth roots and stem, it unfolds into leaves and blossoms. Set the plant before yourselves. It connects itself, in your minds, with a definite concept. Why should this concept belong any less to the whole plant than leaf and blossom? You say the leaves and blossoms exist quite apart from an experiencing subject. The concept appears only when a human being makes an object of the plant. Quite so. But leaves and blossoms also appear on the plant only if there is soil in which the seed can be planted, and light and air in which the blossoms and leaves can unfold. Just so the concept of a plant arises when a thinking being comes into contact with the plant.
5.4 Process Of Growth
 It is quite arbitrary to regard the sum of what we experience of a thing through bare perception as a totality, a whole, while that which thought reveals in it is regarded as a mere accretion which has nothing to do with the thing itself. If I am given a rosebud today, the percept that offers itself to me is complete only for the moment. If I put the bud into water, I shall tomorrow get a very different picture of my object. If I watch the rosebud without interruption, I shall see today's state gradually change into tomorrow's through an infinite number of intermediate stages. The picture which presents itself to me at any one moment is only a chance section out of the continuous process of growth in which the object is engaged. If I do not put the bud into water, a whole series of states, the possibility of which lay in the bud, will not be realized. Similarly, I may be prevented tomorrow from watching the blossom further, and thus carry away an incomplete picture of it.
 It would be a quite unscientific and arbitrary judgment which declared of any haphazard appearance of a thing, this is the thing.
5.5 Indivisible Existence of Concept With Percept
 To regard the sum of perceptual appearances as the thing is no more legitimate. It might be quite possible for a mind to receive the concept at the same time as, and together with, the percept. To such a mind it would never occur that the concept did not belong to the thing. It would have to ascribe to the concept an existence indivisibly bound up with the thing.
 Let me make myself clearer by another example. If I throw a stone horizontally through the air, I perceive it in different places at different times. I connect these places so as to form a line. Mathematics teaches me to distinguish various kinds of lines, one of which is the parabola. I know a parabola to be a line which is produced by a point moving according to a certain well-defined law. If I analyze the conditions under which the stone thrown by me moves, I find that the line of its flight is identical with the line I know as a parabola. That the stone moves exactly in a parabola is a result of the given conditions and follows necessarily from them. The form of the parabola belongs to the whole phenomenon as much as any other feature of it. The hypothetical mind described above which has no need of the roundabout way of thought, would find itself presented, not only with a sequence of visual percepts at different points, but, as part and parcel of these phenomena, also with the parabolic form of the line of flight, which we can add to the phenomenon only by an act of thought.
 It is not due to the real objects that they appear to us at first without their conceptual sides, but to our mental organization. Our whole organization functions in such a way that in the apprehension of every real thing the relevant elements come to us from two sources, viz., from perception and from thought.
 The nature of things is indifferent to the way I am organized for apprehending them. The breach between perception and thought exists only from the moment that I confront objects as spectator. But which elements do, and which do not, belong to the objects, cannot depend on the manner in which I obtain my knowledge of them.
5.6 Isolate And Grasp Single Concepts
 Man is a being with many limitations. First of all, he is a thing among other things. His existence is in space and time. Hence but a limited portion of the total universe can ever be given to him. This limited portion, however, is linked up with other parts on every side both in time and in space. If our existence were so linked with things that every process in the object world were also a process in us, there would be no difference between us and things. Neither would there be any individual objects for us. All processes and events would then pass continuously one into the other. The cosmos would be a unity and a whole complete in itself. The stream of events would nowhere be interrupted. But owing to our limitations we perceive as an individual object what, in truth, is not an individual object at all. Nowhere, e.g., is the particular quality "red" to be found by itself in abstraction. It is surrounded on all sides by other qualities to which it belongs, and without which it could not subsist. For us, however, it is necessary to isolate certain sections of the world and to consider them by themselves. Our eye can seize only single colors one after another out of a manifold color-complex, our understanding only single concepts out of a connected conceptual system. This isolation is a subjective act, which is due to the fact that we are not identical with the world-process, but are only things among other things.
5.7 Self Definition Through Thinking
 It is of the greatest importance for us to determine the relation of ourselves, as things, to all other things. The determining of this relation must be distinguished from merely becoming conscious of ourselves. For this self-awareness we depend on perception just as we do for our awareness of any other thing. The perception of myself reveals to me a number of qualities which I combine into an apprehension of my personality as a whole, just as I combine the qualities, yellow, metallic, hard, etc., in the unity "gold." This kind of self-consciousness does not take me beyond the sphere of what belongs to me. Hence it must be distinguished from the determination of myself by thought. Just as I determine by thought the place of any single percept of the external world in the whole cosmic system, so I fit by an act of thought what I perceive in myself into the order of the world-process. My self-observation restricts me within definite limits, but my thought has nothing to do with these limits. In this sense I am a two-sided being. I am contained within the sphere which I apprehend as that of my personality, but I am also the possessor of an activity which, from a higher standpoint, determines my finite existence. Thought is not individual like sensation and feeling; it is universal. It receives an individual stamp in each separate human being only because it comes to be related to his individual feelings and sensations. By means of these particular colorings of the universal thought, individual men are distinguished from one another. There is only one single concept of "triangle." It is quite immaterial for the content of this concept whether it is in A's consciousness or in B's. It will, however, be grasped by each of the two minds in its own individual way.
5.8 In Thinking We Are The All One Being
 This thought conflicts with a common prejudice which is very hard to overcome. The victims of this prejudice are unable to see that the concept of a triangle which my mind grasps is the same as the concept which my neighbor's mind grasps. The naive man believes himself to be the creator of his concepts. Hence he believes that each person has his private concepts. One of the first things which philosophic thought requires of us is to overcome this prejudice. The one single concept of "triangle" does not split up into many concepts because it is thought by many minds. For the thought of the many is itself a unity.
 In thought we have the element which welds each man's special individuality into one whole with the cosmos. In so far as we sense and feel (perceive), we are isolated individuals; in so far as we think, we are the All-One Being which pervades everything. This is the deeper meaning of our two-sided nature. We are conscious of an absolute principle revealing itself in us, a principle which is universal. But we experience it, not as it issues from the center of the world, but rather at a point on the periphery. Were the former the case, we should know, as soon as ever we became conscious, the solution of the whole world problem. But since we stand at a point on the periphery, and find that our own being is confined within definite limits, we must explore the region which lies beyond our own being with the help of thought, which is the universal cosmic principle manifesting itself in our minds.
 The fact that thought, in us, reaches out beyond our separate existence and relates itself to the universal world-order, gives rise to the desire for knowledge in us. Beings without thought do not experience this desire. When they come in contact with other things no questions arise for them. These other things remain external to such beings. But in thinking beings the concept confronts the external thing. It is that part of the thing which we receive not from without, but from within. To assimilate, to unite, the two elements, the inner and the outer, that is the function of knowledge.
 The percept, thus, is not something finished and self-contained, but one side only of the total reality. The other side is the concept. The act of cognition is the synthesis of percept and concept. And it is only the union of percept and concept which constitutes the whole thing.
5.9 Will Is Objectified In Action And Known By Thinking
 The preceding discussion shows clearly that it is futile to seek for any other common element in the separate things of the world than the ideal content which thinking supplies. All attempts to discover any other principle of unity in the world than this internally coherent ideal content, which we gain for ourselves by the conceptual analysis of our percepts, are bound to fail. Neither a personal God, nor force, nor matter, nor the blind will (of Schopenhauer and Hartmann), can be accepted by us as the universal principle of unity in the world. These principles all belong only to a limited sphere of our experience. Personality we experience only in ourselves, force and matter only in external things. The will, again, can be regarded only as the expression of the activity of our finite personalities. Schopenhauer wants to avoid making "abstract" thought the principle of unity in the world, and seeks instead something which presents itself to him immediately as real. This philosopher holds that we can never solve the riddle of the world so long as we regard it as an "external" world.
"In fact, the meaning for which we seek of that world which is present to us only as our idea, or the transition from the world as mere idea of the knowing subject to whatever it may be besides this, would never be found if the investigator himself were nothing more than the pure knowing subject (a winged cherub without a body). But he himself is rooted in that world: he finds himself in it as an individual, that is to say, his knowledge, which is the necessary supporter of the whole world as idea, is yet always given through the medium of a body, whose affections are, as we have shown, the starting-point for the understanding in the perception of that world. His body is, for the pure knowing subject, an idea like every other idea, an object among objects. Its movements and actions are so far known to him in precisely the same way as the changes of all other perceived objects, and would be just as strange and incomprehensible to him if their meaning were not explained for him in an entirely different way. . . . The body is given in two entirely different ways to the subject of knowledge, who becomes an individual only through his identity with it. It is given as an idea in intelligent perception, as an object among objects and subject to the laws of objects. And it is also given in quite a different way as that which is immediately known to every one, and is signified by the word ' will.' Every true act of his will is also at once and without exception a movement of his body. The act of will and the movement of the body are not two different things objectively known, which the bond of causality unites; they do not stand in the relation of cause and effect; they are one and the same, but they are given in entirely different ways—immediately, and again in perception for the understanding." (The World as Will and Idea, Book 2, § 18.)
Schopenhauer considers himself entitled by these arguments to hold that the will becomes objectified in the human body. He believes that in the activities of the body he has an immediate experience of reality, of the thing-in-itself in the concrete. Against these arguments we must urge that the activities of our body become known to us only through self-observation, and that, as such, they are in no way superior to other percepts. If we want to know their real nature, we can do so only by means of thought, i.e., by fitting them into the ideal system of our concepts and ideas.
5.10 Corresponding Intuition
 One of the most deeply rooted prejudices of the naive mind is the opinion that thinking is abstract and empty of any concrete content. At best, we are told, it supplies but an "ideal" counterpart of the unity of the world, but never that unity itself. Whoever holds this view has never made clear to himself what a percept apart from concepts really is. Let us see what this world of bare percepts is. A mere juxtaposition in space, a mere succession in time, a chaos of disconnected particulars—that is what it is. None of these things which come and go on the stage of perception has any connection with any other. The world is a multiplicity of objects without distinctions of value. None plays any greater part in the nexus of the world than any other. In order to realize that this or that fact has a greater importance than another we must go to thought. As long as we do not think, the rudimentary organ of an animal which has no significance in its life, appears equal in value to its more important limbs. The particular facts reveal their meaning, in themselves and in their relations with other parts of the world, only when thought spins its threads from thing to thing. This activity of thinking has always a content. For it is only through a perfectly definite concrete content that I can know why the snail belongs to a lower type of organization than the lion. The mere appearance, the percept, gives me no content which could inform me as to the degree of perfection of the organization.
 Thought contributes this content to the percept from the world of concepts and ideas. In contrast with the content of perception which is given to us from without, the content of thought appears within our minds. The form in which thought first appears in consciousness we will call "intuition." Intuition is to thoughts what observation is to percepts. Intuition and observation are the sources of our knowledge. An external object which we observe remains unintelligible to us, until the corresponding intuition arises within us which adds to the reality those sides of it which are lacking in the percept. To anyone who is, incapable of supplying the relevant intuitions, the full nature of the real remains a sealed book. Just as the color-blind person sees only differences of brightness without any color qualities, so the mind which lacks intuition sees only disconnected fragments of percepts.
 To explain a thing, to make it intelligible, means nothing else than to place it in the context from which it has been torn by the peculiar organization of our minds, described above. Nothing can possibly exist cut off from the universe. Hence all isolation of objects has only subjective validity for minds organized like ours. For us the universe is split up into above and below, before and after, cause and effect, object and idea, matter and force, object and subject, etc. The objects which, in observation, appear to us as separate, become combined, bit by bit, through the coherent, unified system of our intuitions. By thought we fuse again into one whole all that perception has separated.
 An object presents riddles to our understanding so long as it exists in isolation. But this is an abstraction of our own making and can be unmade again in the world of concepts.
5.11 Conceptual Connections Of Percepts
 Except through thought and perception nothing is given to us directly. The question now arises as to the interpretation of percepts on our theory. We have learnt that the proof which Critical Idealism offers for the subjective nature of percepts collapses. But the exhibition of the falsity of the proof is not, by itself, sufficient to show that the doctrine itself is an error. Critical Idealism does not base its proof on the absolute nature of thought, but relies on the argument that Naive Realism, when followed to its logical conclusion, contradicts itself. How does the matter appear when we recognize the absoluteness of thought?
 Let us assume that a certain percept, e.g., red, appears in consciousness. To continued observation, the percept shows itself to be connected with other percepts, e.g., a certain figure, temperature, and touch-qualities. This complex of percepts I call an object in the world of sense. I can now ask myself: Over and above the percepts just mentioned, what else is there in the section of space in which they are? I shall then find mechanical, chemical, and other processes in that section of space. I next go further and study the processes which take place between the object and my sense-organs. I shall find oscillations in an elastic medium, the character of which has not the least in common with the percepts from which I started. I get the same result if I trace further the connection between sense-organs and brain. In each of these inquiries I gather new percepts, but the connecting thread which binds all these spatially and temporally separated percepts into one whole, is thought. The air vibrations which carry sound are given to me as percepts just like the sound. Thought alone links all these percepts one to the other and exhibits them in their reciprocal relations. We have no right to say that over and above our immediate percepts there is anything except the ideal nexus of percepts (which thought has to reveal). The relation of the object perceived to the perceiving subject, which relation transcends the bare percept, is therefore purely ideal, i.e., capable of being expressed only through concepts. Only if it were possible to perceive how the object of perception affects the perceiving subject, or, alternatively, only if I could watch the construction of the perceptual complex through the subject, could we speak as modern Physiology, and the Critical Idealism which is based on it, speak. Their theory confuses an ideal relation (that of the object to the subject) with a process of which we could speak only if it were possible to perceive it. The proposition, "No color without a color-sensing eye," cannot be taken to mean that the eye produces the color, but only that an ideal relation, recognizable by thought, subsists between the percept "color" and the percept "eye."
To empirical science belongs the task of ascertaining how the properties of the eye and those of the colors are related to one another; by means of what structures the organ of sight makes possible the perception of colors, etc. I can trace how one percept succeeds another and how one is related to others in space, and I can formulate these relations in conceptual terms, but I can never perceive how a percept originates out of the non-perceptible. All attempts to seek any relations between percepts other than conceptual relations must of necessity fail.
5.12 Conceptual Intuition Corresponds To Objective Percept
 What then is a percept? This question, asked in this general way, is absurd. A percept appears always as a perfectly determinate, concrete content. This content is immediately given and is completely contained in the given. The only question one can ask concerning the given content is, what it is apart from perception, that is, what it is for thought. The question concerning the "what" of a percept can, therefore, only refer to the conceptual intuition which corresponds to the percept. From this point of view, the problem of the subjectivity of percepts, in the sense in which the Critical Idealists debate it, cannot be raised at all. Only that which is experienced as belonging to the subject can be termed "subjective." To form a link between subject and object is impossible for any real process, in the naive sense of the word "real," in which it means a process which can be perceived. That is possible only for thought. For us, then, "objective" means that which, for perception, presents itself as external to the perceiving subject. As subject of perception I remain perceptible to myself after the table which now stands before me has disappeared from my field of observation. The perception of the table has produced a modification in me which persists like myself. I preserve an image of the table which now forms part of my Self. Modern Psychology terms this image a "memory-idea." Now this is the only thing which has any right to be called the idea of the table. For it is the perceptible modification of my own mental state through the presence of the table in my visual field. Moreover, it does not mean a modification in some "Ego-in-itself" behind the perceiving subject, but the modification of the perceiving subject itself. The idea is, therefore, a subjective percept in contrast with the objective percept which occurs when the object is present in the perceptual field. The false identification of the subjective with this objective percept leads to the misunderstanding of Idealism: The world is my idea.
 Our next task must be to define the concept of "idea" more nearly. What we have said about it so far does not give us the concept, but only shows us where in the perceptual field ideas are to be found. The exact concept of "idea" will also make it possible for us to obtain a satisfactory understanding of the relation of idea and object. This will then lead us over the border-line, where the relation of subject to object is brought down from the purely conceptual field of knowledge into concrete individual life. Once we know how we are to conceive the world, it will be an easy task to adapt ourselves to it. Only when we know to what object we are to devote our activity can we put our whole energy into our actions.
* Knowledge is transcendental when it is aware that nothing can be asserted directly about the thing-in-itself but makes indirect inferences from the subjective which is known to the unknown which lies beyond the subjective (transcendental). The thing-in-itself is, according to this view, beyond the sphere of the world of immediate experience; in other words, it is transcendent. Our world can, however, be transcendentally related to the transcendent. Hartmann's theory is called Realism because it proceeds from the subjective, the mental, to the transcendent, the real.
Addition to the Revised Edition (1918)
 The view which I have here outlined may be regarded as one to which man is led as it were spontaneously, as soon as he begins to reflect about his relation to the world. He then finds himself caught in a system of thoughts which dissolves for him as fast as he frames it. The thoughts which form this system are such that the purely theoretical refutation of them does not exhaust our task. We have to live through them, in order to understand the confusion into which they lead us, and to find the way out. They must figure in any discussion of the relation of man to the world, not for the sake of refuting others whom one believes to be holding mistaken views about this relation, but because it is necessary to understand the confusion in which all first efforts at reflection about such a relation are apt to issue. One needs to learn by experience how to refute oneself with respect to these first reflections. This is the point of view from which the arguments of the preceding chapter are to be understood.
 Whoever tries to work out for himself a theory of the relation of man to the world, becomes aware of the fact that he creates this relation, at least in part, by forming ideas about the things and events in the world. In consequence, his attention is deflected from what exists outside in the world and directed towards his inner world, the realm of his ideas. He begins to say to himself, it is impossible for me to stand in relation to any thing or event, unless an idea appears in me. From this fact, once noticed, it is but a step to the theory: all that I experience is only my ideas; of the existence of a world outside I know only in so far as it is an idea in me. With this theory, man abandons the stand point of Naive Realism which he occupies prior to all reflection about his relation to the world. So long as he stands there, he believes that he is dealing with real things, but reflection about himself drives him away from this position. Reflection does not reveal to his gaze a real world such as naive consciousness claims to have before it. Reflection reveals to him only his ideas; they interpose themselves between his own nature and a supposedly real world, such as the naive point of view confidently affirms. The interposition of the world of ideas prevents man from perceiving any longer such a real world. He must suppose that he is blind to such a reality. Thus arises the concept of a "thing-in-itself" which is inaccessible to knowledge.
So long as we consider only the relation to the world into which man appears to enter through the stream of his ideas, we can hardly avoid framing this type of theory. Yet we cannot remain at the point of view of Naive Realism except at the price of closing our minds artificially to the desire for knowledge. The existence of this desire for knowledge about the relation of man to the world proves that the naive point of view must be abandoned. If the naive point of view yielded anything which we could acknowledge as truth, we could not experience this desire.
But mere abandonment of the naive point of view does not lead to any other view which we could regard as true, so long as we retain, without noticing it, the type of theory which the naive point of view imposes on us. This is the mistake made by the man who says, I experience only my ideas, and though I think that I am dealing with real things, I am actually conscious of nothing but my ideas of real things. I must, therefore, suppose that genuine realities, "things-in-themselves," exist only outside the boundary of my consciousness; that they are inaccessible to my immediate knowledge; but that they somehow come into contact with me and influence me so as to make a world of ideas arise in me. Whoever thinks thus, duplicates in thought the world before him by adding another. But, strictly he ought to begin his whole theorizing over again with regard to this second world. For the unknown "thing-in-itself," in its relation to man's own nature, is conceived in exactly the same way as is the known thing of the naively realistic point of view.
There is only one way of escaping from the confusion into which one falls, by critical reflection on this naive point of view. This is to observe that, at the very heart of everything we can experience, be it within the mind or outside in the world of perception, there is something, which does not share the fate of an idea inter posing itself between the real event and the contemplating mind. This something is thinking. With regard to thinking we can maintain the point of view of Naive Realism. If we mistakenly abandon it, it is only because we have learnt that we must abandon it for other mental activities, but overlook that what we have found to be true for other activities, does not apply to thinking. When we realize this, we gain access to the further insight that, in thinking and through thinking, man necessarily comes to know the very thing to which he appears to blind himself by interposing between the world and himself the stream of his ideas.
A critic highly esteemed by the author of this book has objected that this discussion of thinking stops at a naively realistic theory of thinking, as shown by the fact that the real world and the world of ideas are held to be identical. However, the author believes himself to have shown in this very discussion that the validity of "Naive Realism," as applied to thinking, results inevitably from an unprejudiced study of thinking; and that Naive Realism, in so far as it is invalid for other mental activities, is overcome through the recognition of the true nature of thinking.
6. HUMAN INDIVIDUALITY
6.0 Corresponding Concept Relates Self To The World
 PHILOSOPHERS have found the chief difficulty in the explanation of ideas in the fact that we are not identical with the external objects, and yet our ideas must have a form corresponding to their objects. But on closer inspection it turns out that this difficulty does not really exist. We certainly are not identical with the external things, but we belong together with them to one and the same world. The stream of the universal cosmic process passes through that segment of the world which, to my perception, is myself as subject. So far as my perception goes, I am, in the first instance, confined within the limits bounded by my skin. But all that is contained within the skin belongs to the cosmos as a whole. Hence, for a relation to subsist between my organism and an object external to me, it is by no means necessary that something of the object should slip into me, or make an impression on my mind, like a signet ring on wax. The question, How do I gain knowledge of that tree ten feet away from me, is utterly misleading. It springs from the view that the boundaries of my body are absolute barriers, through which information about external things filters into me. The forces which are active within my body are the same as those which exist outside. I am, therefore, really identical with the objects; not, however, I in so far as I am subject of perception, but I in so far as I am a part within the universal cosmic process. The percept of the tree belongs to the same whole as my Self. The universal cosmic process produces alike, here the percept of the tree, and there the percept of my Self. Were I a world-creator instead of a world-knower, subject and object (percept and self) would originate in one act. For they condition one another reciprocally. As world-knower I can discover the common element in both, so far as they are complementary aspects of the world, only through thought which by means of concepts relates the one to the other.
6.1 Sense Perception Of Motion
 The most difficult to drive from the field are the so-called physiological proofs of the subjectivity of our percepts. When I exert pressure on the skin of my body, I experience it as a pressure sensation. This same pressure can be sensed as light by the eye, as sound by the ear. I experience an electrical shock by the eye as light, by the ear as sound, by the nerves of the skin as touch, and by the nose as a smell of phosphorus. What follows from these facts? Only this: I experience an electrical shock, or, as the case may be, a pressure followed by a light, or a sound, or, it may be, a certain smell, etc. If there were no eye present, then no light quality would accompany the perception of the mechanical vibrations in my environment; without the presence of the ear, no sound, etc. But what right have we to say that in the absence of sense-organs the whole process would not exist at all? All those who, from the fact that an electrical process causes a sensation of light in the eye, conclude that what we sense as light is only a mechanical process of motion, forget that they are only arguing from one percept to another, and not at all to something altogether transcending percepts. Just as we can say that the eye perceives a mechanical process of motion in its surroundings as light, so we can affirm that every change in an object, determined by natural law, is perceived by us as a process of motion. If I draw twelve pictures of a horse on the circumference of a rotating disc, reproducing exactly the positions which the horse's body successively assumes in movement, I can, by rotating the disc, produce the illusion of movement. I need only look through an opening in such a way that, at regular intervals, I perceive the successive positions of the horse. I perceive, not separate pictures of twelve horses, but one picture of a single galloping horse.
 The above-mentioned physiological facts cannot, therefore, throw any light on the relation of percept to idea. Hence, we must seek a relation some other way.
6.2 Idea: Intuition Related To A Percept
 The moment a percept appears in my field of consciousness, thought, too, becomes active in me. A member of my thought-system, a definite intuition, a concept, connects itself with the percept. When, next, the percept disappears from my field of vision, what remains? The intuition, with the reference to the particular percept which it acquired in the moment of perception. The degree of vividness with which I can subsequently recall this reference depends on the manner in which my mental and bodily organism is working. An idea is nothing but an intuition related to a particular percept; it is a concept which was once connected with a certain percept, and which retains this reference to the percept. My concept of a lion is not constructed out of my percepts of a lion; but my idea of a lion is formed under the guidance of the percepts. I can teach someone to form the concept of a lion without his ever having seen a lion, but I can never give him a living idea of it without the help of his own perception.
6.3 Idea: Individualized Concept
 An idea is therefore nothing but an individualized concept. And now we can see how real objects can be represented to us by ideas. The full reality of a thing is present to us in the moment of observation through the combination of concept and percept. The concept acquires by means of the percept an individualized form, a relation to this particular percept. In this individualized form which carries with it, as an essential feature, the reference to the percept, it continues to exist in us and constitutes the idea of the thing in question. If we come across a second thing with which the same concept connects itself, we recognize the second as being of the same kind as the first; if we come across the same thing twice, we find in our conceptual system, not merely a corresponding concept, but the individualized concept with its characteristic relation to this same object, and thus we recognize the object again.
 The idea, then, stands between the percept and the concept. It is the determinate concept which points to the percept.
6.4 Idea: Acquired Experience
 The sum of my ideas may be called my experience. The man who has the greater number of individualized concepts will be the man of richer experience. A man who lacks all power of intuition is not capable of acquiring experience. The objects simply disappear again from the field of his consciousness, because he lacks the concepts which he ought to bring into relation with them. On the other hand, a man whose faculty of thought is well developed, but whose perception functions badly owing to his clumsy sense-organs, will be no better able to gain experience. He can, it is true, by one means and another acquire concepts; but the living reference to particular objects is lacking to his intuitions. The unthinking traveler and the student absorbed in abstract conceptual systems are alike incapable of acquiring a rich experience.
6.5 Idea: Subjective Representation Of Reality
 Reality presents itself to us as the union of percept and concept; and the subjective representation of this reality presents itself to us as idea.
 If our personality expressed itself only in cognition, the totality of all that is objective would be contained in percept, concept and idea.
6.6 Refer Percepts To Feelings
 However, we are not satisfied merely to refer percepts, by means of thinking, to concepts, but we relate them also to our private subjectivity, our individual Ego. The expression of this relation to us as individuals is feeling, which manifests itself as pleasure and pain.
6.7 Two-Fold Nature: Thinking And Feeling
 Thinking and feeling correspond to the two-fold nature of our being to which reference has already been made. By means of thought we take an active part in the universal cosmic process. By means of feeling we withdraw ourselves into the narrow precincts of our own being.
 Thought links us to the world; feeling leads us back into ourselves and thus makes us individuals. Were we merely thinking and perceiving beings, our whole life would flow along in monotonous indifference. Could we only know ourselves as Selves, we should be totally indifferent to ourselves. It is only because with self-knowledge we experience self-feeling, and with the perception of objects pleasure and pain, that we live as individuals whose existence is not exhausted by the conceptual relations in which they stand to the rest of the world, but who have a special value in themselves.
 One might be tempted to regard the life of feeling as something more richly saturated with reality than the apprehension of the world by thought. But the reply to this is that the life of feeling, after all, has this richer meaning only for my individual self. For the universe as a whole my feelings can be of value only if, as percepts of myself, they enter into connection with a concept and in this roundabout way become links in the cosmos.
6.8 True Individuality
 Our life is a continual oscillation between our share in the universal world-process and our own individual existence. The farther we ascend into the universal nature of thought where the individual, at last, interests us only as an example, an instance, of the concept, the more the character of something individual, of the quite determinate, unique personality, becomes lost in us. The farther we descend into the depths of our own private life and allow the vibrations of our feelings to accompany all our experiences of the outer world, the more we cut ourselves off from the universal life. True individuality belongs to him whose feelings reach up to the farthest possible extent into the region of the ideal. There are men in whom even the most general ideas still bear that peculiar personal tinge which shows unmistakably their connection with their author. There are others whose concepts come before us as devoid of any trace of individual coloring as if they had not been produced by a being of flesh and blood at all.
6.9 Point Of View
 Even ideas give to our conceptual life an individual stamp. Each one of us has his special standpoint from which he looks out on the world. His concepts link themselves to his percepts. He has his own special way of forming general concepts. This special character results for each of us from his special standpoint in the world, from the way in which the range of his percepts is dependent on the place in the whole where he exists. The conditions of individuality here indicated, we call the milieu.
6.10 Intensity Of Feelings
 This special character of our experience must be distinguished from another which depends on our peculiar organization. Each of us, as we know, is organized as a unique, fully determined individual. Each of us combines special feelings, and these in the most varying degrees of intensity, with his percepts. This is just the individual element in the personality of each of us. It is what remains over when we have allowed fully for all the determining factors in our milieu.
6.11 Education Of Feelings
 A life of feeling, wholly devoid of thought, would gradually lose all connection with the world. But man is meant to be a whole, and knowledge of objects will go hand-in-hand for him with the development and education of the feeling-side of his nature.
6.12 Living Concepts
 Feeling is the means whereby, in the first instance, concepts gain concrete life.