4. THE WORLD AS PERCEPTION
4.0 Reactive Thinking
 Concepts and Ideas are formed by thinking. What a concept is cannot be expressed in words. Words can only draw our attention to the fact we have concepts. When someone sees a tree, his thinking reacts to his observation. An ideal element is added to the object, and the observer regards the object and Ideal complement as belonging together. When the object disappears from his field of observation, only the Ideal counterpart remains. This is the concept of the object.
The wider the range of our experience, the larger the number of our concepts. Concepts are never found in isolation. They combine to form an ordered and systematic whole. For example, the concept “organism” links up with others such as "development according to law" and "growth." Other concepts, formed from single objects, merge together into a unity. All concepts I form of particular lions merge in the universal concept "lion." In this way, all the single concepts unite to form an enclosed, conceptual system in which each has its special place. Ideas are not qualitatively different from concepts. They are filled with more content, are more complex and more comprehensive concepts.
I must emphasize here that my starting-point is thinking, not concepts and Ideas, which must first be gained by thinking. Thinking precedes concepts and Ideas. Consequently, what I have said about the nature of thought, that it is self-supporting and determined by nothing but itself, cannot simply be transferred and applied to concepts. (I make special mention of this here, as this is where I differ with Hegel, who regards the concept as the primary and original element.)
 Concepts cannot be drawn from observation. This is evident from the fact the growing human being only slowly and gradually builds up the concepts that correspond to the objects in his environment. Concepts are added to observation.
4.1 The Response Of The Mental Process To Observation
 A popular contemporary philosopher, Herbert Spencer, describes the mental process that takes place in response to observation as follows:
 “While wandering through fields in September you hear a rustle a few steps ahead, and see the grass moving by the side of the ditch. You will probably approach the spot to learn what caused the noise and the movement. As you approach, a partridge flutters in the ditch. Seeing this, your curiosity is satisfied; you have what we call an explanation of the phenomena.
The explanation, please notice, amounts to this: Throughout life you have learned through countless experiences that a disturbance among small stationary bodies, is accompanied by the movement of other bodies among them. Because of having generalized the relationship between disturbances and movements, you consider this particular disturbance explained as soon as you find it to be an example of just such a relationship" (First Principles, Part I, par. 23).
A closer analysis leads to a very different description from what Spencer gives. When I hear a noise the first thing I do is search for the concept that fits this observation. Only when I have this concept am I led beyond the noise itself. Whoever does not reflect on the event simply hears the noise and is content to leave it at that. But my thought makes it clear to me that a sound must be the effect of something. Only when I connect the concept of effect with the perception of the noise am I inclined to go beyond the single observation and look for its cause. The concept “effect” calls up the concept “cause.”
My next step is to look for the object that acts as the cause, which I find to be a partridge. But I can never gain the concepts “cause” and “effect” by mere observation, no matter how many cases I observe. Observation calls up thought, and thought shows me how to link separate experiences together.
 If one demands a “strictly objective science” that draws its content from observation alone, then one must also demand that it renounce all thinking. Because thought, by its very nature, goes beyond what is observed.
4.2 The Thinker
 We must now pass from thought to the being who thinks. For it is through the thinker that thought is combined with observation. Human consciousness is the place where concept and observation meet, and are connected to each other. This is, in fact, what characterizes human consciousness. It mediates between thought and observation.
In observation the object appears as given, in thought the mind experiences itself as active. It regards the thing as the object and itself as the thinking subject. When thought is directed to the observed world we have consciousness of objects; when thought is directed to itself we have self-consciousness. Human consciousness must of necessity be also self-consciousness, because it is a thinking consciousness. For when thought contemplates its own activity, the subject makes its own essential nature an object of study. Subject and object are here one and the same.
 It is important to note here that it is only by means of thinking that I am able to define myself as subject and contrast myself with objects. For this reason, thinking should never be regarded as a merely subjective activity. Thinking is above the distinction of subject and object. It produces these two concepts just as it produces all others. When I, as thinking subject, refer a concept to an object, we must not regard this referring as a purely subjective activity. It is not the subject, but thought, that makes the reference.
The subject does not think because it is a subject; rather, it appears to itself as subject because it can think. The activity of thinking consciousness, exercised by a human being as a thinker, is therefore not merely subjective. In fact, it is an activity that is neither subjective nor objective; it transcends both concepts. I should never say that I, as an individual subject, think. The truth is that I, as subject, exist only by the grace of thought. Thought takes me out of myself and relates me to objects. But it also separates me from the objects by setting me over against them, to face them as subject.
 The basis for the dual nature of the human being is that he thinks. His thought embraces himself along with the rest of the world. But also, by means of thought, he defines himself as an individual in contrast with the objective world.
4.3 The Observed Object
 Next, we must ask ourselves: How does the other element—which we have so far simply called the ‘observed object’—enter our consciousness where it comes into contact with thought?
 To answer this question, we must remove from our field of observation all thought that has already been brought into it. For at any moment the content of our consciousness is always pervaded with concepts in a variety of ways.
 Let us imagine a being with fully developed human intelligence originates out of nothing and has the world in front of him. All this being would be aware of, before its thought became active, is the pure content of observation. The world would appear to this being as a chaotic aggregate of disconnected sense-data: colors, sounds, touch, warmth, taste and smell; followed by feelings of pleasure and pain. This aggregate is the content of pure, thought-free observation.
Facing it stands thought, ready to begin its activity as soon as it can find a point of engagement. Experience shows that it soon does. Thought is able to draw connecting threads from one sense-datum to another. It unites specific concepts with these elements, and in this way establishes a relationship between them. We have already seen how a noise we encounter is brought into relationship with another observation by characterizing the first as an effect of the second.
 We will not be tempted to believe these relationships established by thought only have subjective validity, if we recall that in no circumstance can the activity of thought be considered merely subjective.
4.4 The Conscious Subject
 Our next task is to discover, by thoughtful reflection, how the immediately given sense-data—the pure, relationless aggregate of sensory objects—is related to our conscious subject.
 Because of the various ways of using words, it seems necessary for me to come to an agreement with the reader on the meaning of a word that I will use from now on. The word is percept. I will use the word “percept” to refer to “the immediate objects of sensation” mentioned above, insofar as the conscious subject becomes aware of them through observation. It is the observed object, not the process of observing, that I call “percept.”
 I do not choose the term “sensation,” because sensation has a specific meaning in Physiology narrower than my concept of “percept.” I can call an inner feeling a percept, but not a sensation in the physiological use of the term. When I become aware of a feeling it becomes a percept for me, and I can then gain knowledge of it. And the way we gain knowledge of our thought-processes, through observation, is to first notice thought. Then thought too, may be called a percept.
 The unreflective, naive person regards his percepts, as they first appear, to have an existence completely independent of him. When he sees a tree, he believes right away that it is standing there on the spot where his look is directed having the shape, color and details just as he sees it. From this naive standpoint, if a person sees the sun appear in the morning as a disc on the horizon, and then follows the course of this disc, he believes the phenomenon exists and occurs just as he observes it. He clings to this belief until further perceptions contradict the earlier ones. A child, with no experience of distance, reaches for the moon, and does not correct its first impression until it conflicts with later ones.
Every widening of the circle of my perceptions makes me correct my picture of the world. We see this in everyday life, as well as in the intellectual development of humanity. The picture which the ancients made of the relation of the earth to the sun and other celestial bodies, had to be changed by Copernicus, because the ancient picture did not agree with new, previously unknown perceptions. A man who had been born blind said, after an operation performed by Dr Franz, that the picture he had formed of the size of objects before his operation was a very different one. It was formed on the basis of a blind man’s perceptions of touch. He had to correct his touch percepts with his new visual percepts.
4.5 The Perception-Picture
 Why are we forced to make continual corrections to our observations?
 A simple reflection provides the answer to this question. If I stand at one end of a tree-lined avenue, the trees at the far end appear smaller and closer together than those where I am standing. My perception-picture changes when I change my place of observation. Therefore, the way things appear to me is determined by a factor that has to do, not with the object, but with myself as the observer. It is all the same to the avenue where I stand. But the picture I have of it depends to a great extent on my standpoint. In the same way, it makes no difference to the sun and solar system that human beings happen to observe them from the earth. But the perception-picture human beings have of the sun and solar system is determined by their living on the earth.
This dependence of the perception-picture on our place of observation is the easiest to understand. It becomes more difficult when we learn how our perceptual world is dependent on our bodily and mental organization. The physicist teaches us that in the space where we hear a sound, there are vibrations of the air. And in the body where the sound is emitted there are vibrations of its parts. But we only perceive these vibrations as sound if we have normally constructed ears. Without them the whole world would remain forever silent.
The physiologist teaches us there are people who perceive nothing of the wonderful display of colors surrounding us. Their perception-picture only has shades of light and dark. Others fail to perceive just one particular color, such as red. Their picture of the world lacks this color hue, and is different from the average person. I would like to call the dependency of my perception-picture on my place of observation "mathematical," and its dependency on my organization "qualitative." The first determines the relative sizes of my percepts and distances between them, the second their quality. The fact that a red surface appears to me red—this qualitative determination—depends on the structure of my eye.
4.6 The Subjective Perception-Picture
 My perception-pictures, then, are at first subjective. The recognition of the subjective character of our percepts can easily lead us to doubt whether anything objective underlies them at all. We know that a percept, for example the color red or a certain musical tone, is only possible thanks to a specific structure of our organism. From this we can easily be led to believe that the percept, apart from our subjective organization, ceases to be. If not for our act of perceiving it as an object, it has no existence at all.
This view found its classic expression in George Berkeley, who was convinced that when we realize how significant the human subject is for the percept, we can no longer believe in a world that exists apart from a conscious mind. He says:
"Some truths are so near and so obvious to the mind man need only open his eyes to see them. One such truth is this important one: The whole choir of heaven and all things of the earth—in a word, all those bodies which compose the mighty frame of the world—have no subsistence outside the mind. Their sole existence is being perceived or known. Consequently, as long as they are not actually perceived by me, or exist in my mind or in that of some other created spirit, they either have no existence or subsist in the mind of some Eternal Spirit." (Berkeley, Principles of Human Knowledge, Part I, Section 6.)
From this point of view, nothing remains of the percept if we consider it apart from being perceived. There is no color when none is seen, no sound when none is heard. Outside the act of perception, categories such as extension, form, and motion exist just as little as color and sound. Nowhere do we see extension and form alone. They are always bound up with color or other qualitative elements unquestionably dependent on our subjectivity. If these disappear when we cease to perceive them, then extension and form, which are bound up with them, must disappear also.
 The objection can be made that, even if figure, color, sound, and so forth do not existence outside the act of perception, there must still be something else there. Something must exist independently of our consciousness and be similar to our conscious perception-pictures. The Berkeleyan response would be to say: A color can only resemble a color and a figure can only resemble a figure. Our percepts can only resemble our percepts, and nothing else.
Even what we call an object is nothing but a collection of percepts connected in a certain way. If I strip a table of its figure, extension, color, etc.—in other words everything that is only my percept—then nothing is left. Carried to its logical conclusion, this view leads to the assertion: The objects of my perception are there through me, and only insofar and as long as I am perceiving them. They disappear with the perceiving and have no meaning without it. Other than my percepts, I know of no objects and cannot know of any.
 To the claim that we can know only our percepts, no objection is made as long as it is only meant as a general fact that the percept is partly determined by the organization of the perceiving subject. It would be very different if we were able to determine the exact role our perceiving plays in bringing about a percept. We would then know what happens to the percept during the act of perception. And we could also determine what properties it has before it is perceived.
 This leads us to turn our attention from the perceived object to the perceiving subject. I do not only perceive other things; I also perceive myself.
Self-perception first reveals that I am the enduring element in a continuous coming and going of perception-pictures. The awareness of myself can come up in my consciousness at any time, while I am having other perceptions. However, when I am absorbed in the perception of a given object I am, for the moment, aware only of this object. The awareness of myself can be added to this. I am then not only conscious of the object, but also of my own personality, standing over against the object and observing it. I not only see a tree; I know it is I seeing it.
I also know something goes on in me while I am observing the tree. When the tree disappears from my field of vision, an after-effect of this process remains: an image of the tree. This image has become associated with my Self during my observation. My Self has become enriched; a new element has been added to its content. I call this element my idea (Vorstellung) of the tree.
I would never be in a position to speak of ideas if I did not experience them by being aware of my Self. Percepts would come and go; I would simply let them pass by. It is only because I perceive my Self that I notice that with each perception the content of my Self, too, is changed. By noticing the connection between the observation of the object and the changes that occur in me, I then speak of having an idea.
4.8 Perception Of Ideas
 I perceive ideas in my Self in the same way I perceive colors, sounds, etc. in other objects. From this point of view, I can now make the further distinction of calling these other objects that confront me the outer world, while the content of my Self-observation I call my inner world.
The failure to recognize the relationship between idea and object has led to the greatest misunderstandings in modern philosophy. The perception of a change in me, the modification my Self undergoes, is thrust into the foreground, while the object causing this modification is completely lost sight of. As a consequence it is said: We do not perceive the objects, but only our ideas. I know nothing, so it is claimed, of the object of my observation; the table itself. I know only of the change that is going on within me while I am perceiving the table.
This view should not be confused with the Berkeleyan view mentioned previously. Berkeley upholds the subjective nature of my perceptual content, but he does not say I can know only my own ideas. He limits my knowledge to my ideas because, in his view, there are no objects other than ideas. What I see as a table no longer exists, according to Berkeley, when I cease to look at it. This is why for Berkeley my percepts are created directly by the power of God. I see a table because God calls forth this percept in me. For Berkeley nothing is real except God and human spirits. What we call the "world" is present only within spirits. What the naive person calls the outer world, or physical nature, does not exist according to Berkeley.
Berkeley’s view stands in contrast to the currently prevailing Kantian view. This also limits our knowledge of the world to our ideas. But it does not do so because of a conviction that nothing other than ideas exist. Rather, the Kantian view believes we are organized in a way that we can learn only of the changes undergone by our own Self, not the things-in-themselves that cause them. This view draws a conclusion on the fact I can know only my ideas. According to the Kantian view, the reason we know only our ideas is not that no reality exists independent of these ideas. It is because the human subject cannot receive such a reality into itself directly. The mind can only through "the medium of its subjective thoughts imagine it, think it, cognize it, or perhaps fail to cognize it" (O. Liebmann, Analysis of Reality, p. 28). Kantians believe their view expresses something absolutely certain, something immediately evident without any need of proof.
“The first fundamental principle the philosopher must clearly grasp is the recognition that our knowledge does not initially go beyond our ideas. Our ideas are the only things we experience directly and learn to know directly. The fact that we experience ideas directly means not even the most radical doubt can rob us of our knowledge of them. On the other hand, all knowledge that does go beyond my ideas—taking ideas here in the widest sense to include all psychical processes—is open to doubt. At the very beginning of all philosophy, it is necessary to state explicitly that all knowledge that goes beyond ideas is open to doubt.”
4.9 Our Organization
Volkelt's book on Immanuel Kant’s Theory of Knowledge begins with the statement given above. What is presented here as if it were an immediate and obvious truth, is really the result of the following thought process. "Naive common sense believes that things, just as we perceive them, also exist outside our minds. Physics, physiology and psychology, however, teach us that for perception to take place our organization is necessary. Consequently, we cannot know anything about external objects other than what our organization transmits to us. What we perceive as objects are modifications that occur in our organization, not the things themselves." This line of reasoning has been characterized by Eduard von Hartmann as leading inevitably to the conviction that we can have direct knowledge only of our ideas (see Hartmann’s “Basic Problem of Theory of Knowledge”, p.16-40).
Because outside our organism we find vibrations of physical bodies and of the air perceived by us as sound. This view reasons that what we call sound is nothing more than a subjective reaction of our organism to these motions in the external world. In the same way color and warmth are only modifications of our organism. Our percepts of warmth and color are the effects of processes in the external world. These external processes are entirely different from what we experience as warmth and color. When these processes stimulate the nerves in my skin, I perceive warmth. When they stimulate the optic nerve, I perceive light and color. Light, color, and warmth, then, are the way the nerves of my sense organs react to outside stimuli. Even the sense of touch does not transmit to me the objects of the outer world, but only conditions in myself.
The physicist thinks of bodies as consisting of infinitely small parts called molecules. These molecules are not in direct contact with each other, but have certain distances separating them. Between them is empty space. Across this space they act on each other by forces of attraction and repulsion. When I place my hand on an object, the molecules of my hand never touch the molecules of the object. There always remains a certain distance between object and hand. What I feel as the resistance of the object, is nothing other than the effect of the force of repulsion its molecules exert on my hand. I remain completely external to the object. All I perceive is its effect on my organism.
 An extension of this idea is the Specific Nerve Energies theory, proposed by J. Müller (1801- 1858). According to this theory, each sense-organ has the peculiar quality of reacting to all external stimuli in only one specific way. Stimulation of the optic nerve results in perception of light. It does not matter whether the nerve stimulation is due to what we call light, or to mechanical pressure, or to an electric current. Conversely, the same external stimulus applied to different senses evokes different sensations. This seems to indicate that our sense-organs can transmit only what occurs within them, and transmit nothing from the outer world. The senses determine the percepts, each according to its own nature.
 Physiology further shows there can be no direct knowledge even of the effects objects have within our sense-organs. When the physiologist follows the processes that take place in the body, he finds the effects of external motion already transformed within the sense organs in a variety of ways. We see this most clearly in the eye and the ear. Both are very complicated organs that alter the external stimulus considerably, before conveying it to the corresponding nerve. From the peripheral nerve-ending, the already changed stimulus is transmitted further to the brain, and here the central organ is stimulated. From this, it is concluded that the external process undergoes a series of transformations before it enters consciousness.
What finally takes place in the brain is connected to the external stimuli by so many intermediate processes, any similarity between the two is out of the question. What the brain finally transmits to the human psyche is neither external processes, nor processes in the sense-organs, but only processes inside the brain. Yet even these are not perceived directly by our inner being. What we finally have in consciousness are not brain-processes at all, but sensations. My sensation of red has absolutely no similarity to the process taking place in the brain when I sense red. The redness that occurs in the mind is an effect, and the brain process is its cause. This is why Hartmann says (The Basic Problem of Epistemology), "What the subject perceives are always only modifications of his own psychical states and nothing else."
When I have sensations, however, they are still far from being grouped into what I perceive as "things." After all, only single sensations can be transmitted to me by the brain. Sensations of “hard” and “soft” are transmitted to me by the sense of touch; color and light by the sense of sight. Yet all these are found united in one object. This unification, then, can only be brought about by our psychical nature. The psyche constructs things out of the various sensations transmitted to it by the brain. My brain conveys to me the single sensations of sight, touch and hearing by entirely different pathways. The psyche then combines the sensations to form the idea “trumpet.” This final stage of the process (the idea of the trumpet) is the very first thing to enter my consciousness. In this result nothing can any longer be found of what exists outside me and made the original impression on my senses. The external object has been completely lost on the way to the brain and through the brain to the human psyche.
4.10 The External World Is A Projection Of My Psyche
 It would be hard to find in the history of human intellectual life an edifice of thought built up with greater ingenuity, and yet, on closer analysis, collapses into nothing. Let us look more closely at the way it has been constructed. The theory begins with what is given in naive consciousness, the thing as perceived. Then it shows that none of the qualities found in it would exist for us if we had no sense organs. No eye—no color. So color is not yet present in what affects the eye. The color first arises through the interaction of the eye with the object. The object, then, is colorless. But the color is not present in the eye either. In the eye there is a chemical or physical process that is conducted by the nerve to the brain, where it sets off another process. The process in the brain is not yet the color. The color is produced in our psychical nature by the brain process. But even here I am still not conscious of it. It is first projected outwards by our psyche onto a spatial body in the external world. Here, finally, I see the color, as a quality of this body.
We have come full circle. We have become conscious of a colored object. That comes first. Now the thought-operation begins. If I had no eyes, the object would be colorless for me. So I cannot attribute the color to the object. I go looking for it. I look for it in the eye,—in vain; in the nerve,—also in vain; in the brain,—again in vain.
Finally, I look for it in the psyche. Here I find it, but unconnected with the spatial body. I only find the colored object again—there, at the place where I started. The circle is closed. The theory leads me to believe that what the naive person thinks is existing outside him in space, is really a creation of my own psyche.
4.11 The External Percept Is My Idea
 As long as one stops here, everything seems to fit perfectly. But we must go over it again from the beginning. Up to now I have been dealing with an object—the external percept. As a naive person, I had an an entirely false view of it. I thought the percept, just as I perceive it, had objective existence. Now I realize it disappears as I represent it to myself in the act of perceiving. The external percept is no more than a modification of my mental condition.
Do I still have the right to take it as a starting point for my reflections? Can I say it has an effect on my psyche? Previously I believed the table had an effect on me, and brought about an idea of itself in me. From now on I must treat the table as itself an idea. But then to be logically consistent, my sense organs and the processes going on in them must also be only subjective manifestations. I have no right to speak of a real eye, only of my idea of the eye. The same would apply to the nerve paths and the brain process. And even to the process that occurs within the psyche itself, by which things are supposedly constructed out of the chaos of various sensations.
If I go through each step of the act of cognition once again, assuming the correctness of the first circular line of thought, the cognitive act described reveals itself as a web of ideas that, as such, cannot possibly act on each other. I cannot say: My idea of the object acts on my idea of the eye, and the result of this interaction is my idea of color. But I do not need to. For as soon as it is clear to me that my sense organs and their activity, and my nerve and psychic processes, are also known to me only through perception, then the full impossibility of the described line of thought reveals itself. It is true to say: For me there is no percept without the corresponding sense organ. But it is just as true to say: There is no sense-organ without a percept of it.
From the percept of a table I can pass to the eye that sees it, to the nerves of the hand that touch it. But what takes place within these I can learn, once again, only through perception. Then I soon notice there is no trace of similarity between the process taking place in the eye and what I perceive as color. I cannot deny my color percept just because I can point out the process taking place in the eye during this perception. Nor can I find the color in the nerve and brain-processes. All I do is connect new percepts located within my organism to the first percept, which the naive person locates outside his organism. I simply pass from one percept to the next.
 In addition, there is a gap in the whole chain of reasoning. I can follow the processes in my organism up to those in my brain. My assumptions, though, become more and more hypothetical the closer I come to the central processes in the brain. The method of external observation ends with the process in the brain. More precisely, it ends with what I would observe if I examine the brain using the instruments and methods of Physics and Chemistry. The method of internal observation, or introspection, begins with the sensations, and continues up to the construction of things out of the material of sensation. At the point of transition from brain process to sensation, there is a break in the method of observation.
 The way of thinking just described, known as Critical Idealism, stands in contrast to the position of naive common sense, known as Naive Realism. The Critical Idealist makes the error of characterizing one kind of percept as an idea, while accepting the other kind in exactly the same way as the Naive Realist, whom he claims to have refuted. He sets out to prove that our percepts are representational ideas, while naively accepting the percepts belonging to his own body as objectively valid facts. What is more, he fails to see he is confusing two fields of observation, between which he can find no connecting link.
4.12 The Bodily Organism Has Objective Existence
 Critical idealism can only refute Naive Realism if it accepts, in naive-realistic fashion, that one's own organism has objective existence. As soon as the Idealist realizes the percepts of his own organism are exactly the same kind as those Naive Realism assumes to have objective existence, he can no longer use those percepts as a secure 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 thinking that the content of the perceived world is a product of our mental organization. One would have to accept that the idea "color" was only a modification of the idea "eye." So-called Critical Idealism cannot be proved without borrowing the assumptions of Naive Realism. The apparent refutation of Naive Realism is achieved only by uncritically accepting its basic assumptions as valid in another area.
 This much, then, is certain: Investigation of the field of perception cannot prove the correctness of Critical Idealism, and, consequently, cannot strip percepts of their objective character.
 But even less can the principle, "The perceived world is my idea" be claimed as obvious in need of no proof. Schopenhauer begins his main work, The World as Will and Idea, with the words:
"The world is my idea—this truth applies to every living and cognizing being, although the human being alone can bring it into reflective, abstract consciousness. And when he really does this, he will have attained to philosophical self-knowledge. It then becomes clear and certain to him that he knows no sun and no earth, but only an eye that sees a sun, and a hand that feels the earth. The world around him is present only as an idea. It is there only in relation to something else, to the one who depicts it, namely, himself. If ever a truth could be declared a priori, it is this one; for it expresses the most general form of all possible and thinkable experience. A form that is more universal than all others, than time, space, or causality, for all these presuppose it …” (The World as Will and Idea, Book I, par. I.)
This whole theory, based on the principle “The world is my idea” collapses in the face of the fact, noted above, that the eye and hand are percepts just as much as the sun and the earth. In Schopenhauer’s terms, and using his style of expression, one could respond: My eye that sees the sun, and my hand that feels the earth, are my ideas just like the sun and the earth. Put in this way, it is immediately clear Schopenhauer’s proposition cancels itself out. For only my real eye and my real hand could have the ideas of sun and earth as their modifications—my ideas “eye” and “hand” could not. Yet it is only in terms of these ideas that Critical Idealism is entitled to speak.
 Critical Idealism is completely unable to gain insight into the relationship between percepts and ideas. It cannot begin to make the distinction we indicated earlier, between what happens to the percept during the act of perception, and what must already be present in it before it is perceived. To do this, we must find another way to approach this question.