In vain did Aristotle protest against the Platonic splitting of the world picture. He saw in nature a unified being, which contains ideas just as much as it does the things and phenomena perceptible to the senses. Only within the human spirit can the ideas have an independent existence. But in this independent state they cannot be credited with any reality. Only the soul can separate them from the perceptible things with which, together, they constitute reality. If Western philosophy had linked onto the rightly understood views of Aristotle, then it would have been preserved from much of what must appear to the Goethean world view as aberration.
But Aristotle, rightly understood, to begin with made uncomfortable many a person who wanted to gain a foundation in thought for the Christian picture of things. Many a person who considered himself to be a genuinely “Christian” thinker' did not know what to do with a conception of nature which places the highest active principle into the world of our experience. Many Christian philosophers and theologians' therefore gave a new interpretation to Aristotle. They attached a meaning to his views which, in their opinion, was able to serve as a logical support for Christian dogma. Man's spirit should not seek within things for their creative ideas. The truth is, indeed, imparted to human beings by God in the form of revelation. Reason is only meant to confirm what God has revealed. Aristotelian principles were interpreted by the Christian thinkers of the Middle Ages in such a way that the religious truth of salvation received its philosophical reinforcement through these principles. It is the conception of Thomas' Aquinas, the most significant Christian thinker, which first seeks to weave the Aristotelian thoughts as far and as deeply into the Christian evolution of ideas as was possible at the time of this thinker. According to this conception, revelation contains the highest truths, the Bible's teachings of salvation; it is possible, however, for reason to penetrate deeply into things, in the Aristotelian way, and to bring forth from them their content of ideas. Revelation can descend far enough, and reason can lift itself high enough, that the teaching of salvation and human knowledge merge with one another at a certain boundary. Aristotle's way of penetrating into things serves Thomas, therefore, as a way of coming to the realm of revelation.
When, with Bacon of Verulam and Descartes, an era began in which there asserted itself the will to seek the truth through the human personality's own power, then habits of thought tended to lead one to strive only to set up views which, in spite of their seeming independence from the preceding Western world picture, were nevertheless nothing but new forms of1t. Bacon and Descartes had also acquired, as heritage of a degenerate thought world, the pernicious way of looking at the relationship of experience and idea. Bacon had a sense and an understanding only for the particulars of nature. By collecting that which, extending through the manifoldness of space and time, is alike or similar, he believed he arrived at general rules about the processes of nature. Goethe aptly says of him, “For, though he himself always indicates that one should collect the particulars only in order to be able to choose from them, to order them, and finally to arrive at universals, nevertheless, he grants too many rights to the individual cases, and before one can achieve through induction — even the induction which he extols — this simplification and conclusion, the life is gone and the forces consume themselves.” For Bacon these general rules are a means by which it is possible for reason to have a comfortable overview of the region of particularities. But he does not believe that these rules are founded in the ideal content of things and that they are really creative forces of nature. Therefore he also does not seek the idea directly within the particular but rather abstracts it out of a multiplicity of particulars. Someone who does not believe that the idea lives within the individual thing also can have no inclination to seek it there. He accepts the thing the way it presents itself to mere outer perception. Bacon's significance is to be sought in the fact that he drew attention to that outer way of looking at things which had been denigrated by the one-sided Platonism characterized above, that he emphasized that in it lies a source of truth. He was not, however, in a position to help the world of ideas in the same way to establish its rights over against the perceptible world. He declared what is ideal to be a subjective element within the human spirit. His way of thinking is Platonism in reverse. Plato sees reality only in the world of ideas, Bacon only in the world of perception without ideas. Within Bacon's conception there lies the starting point for that attitude of thinkers by which natural scientists are governed right into the present-day. Bacon's conception suffers from an incorrect view about the ideal element of the world of experience. It could not deal rightly with that medieval view, produced by a one-sided way of posing the I question, to the effect that ideas are only names, not realities lying within things.
From other points of view, but no less influenced by one-sidedly Platonizing modes of thought, Descartes began his contemplations three decades after Bacon. He is also afflicted with the Original Sin of Western thought, with mistrust toward the unbiased observation of nature. Doubt in the existence and knowability of things is the starting point of his research. He does not direct his gaze upon the things in order to gain access to certainty, but rather he seeks out a very little door, a way, in the fullest sense of the word, of sneaking in. He withdraws into the most intimate region of thinking. Everything that I have believed up to now as truth might be false, he says to himself. What I have thought might rest upon delusion. But the one fact does remain nevertheless: that I think about things. Even if I think lies and illusion, I am thinking nevertheless. And if I think, then I also exist. I think, therefore I am. With this Descartes believes that he has gained a sound starting point for all further thinking about things. He asks himself further: is there not still something else in the content of my thinking that points to a true existence? And there he finds the idea of God as the most perfect of all beings. Given that man himself is imperfect, how does the idea of a most perfect being come into his world of thoughts? An imperfect being cannot possibly produce such an idea out of himself. For the most perfect thing that he can think is in fact an imperfect thing. This idea of the most perfect being must itself therefore have been placed into man. Therefore God must also exist. Why, however, should I. perfect being delude us with an illusion? The outer world, which presents itself to us as real, must therefore also be real. Otherwise it would be an illusory picture that the godhead imposes upon us. In this way Descartes seeks to win the trust in reality which, because of inherited feelings, he lacked at fIrst. He seeks truth in an extremely artificial way. He takes his start one-sidedly from thinking. He credits thinking alone with the power to produce conviction. A conviction about observation can only be won if it is provided by thinking. The consequence of this view was that it became the striving of Descartes' successors to determine the whole compass of the truths which thinking can develop out of itself and prove. One wanted to find the sum total of all knowledge out of pure reason. One wanted to take one's start from the simplest immediately clear insights, and proceeding from there to travel through the entire sphere of pure thinking. This system was meant to be built up according to the model of Euclidean geometry. For one was of the view that this also starts from simple, true principles and evolves its entire content through mere deduction, without recourse to observation. In his Ethics Spinoza attempted to provide such a system of the pure truths of reason. He takes a number of mental pictures: substance, attribute, mode, thinking, extension, etc., and investigates in a purely intellectual way the relationships and content of these mental pictures. The being of reality supposedly expresses itself in an edifice of thought. Spinoza regards only the knowledge arising through this activity, foreign to reality, as one that corresponds to the true being of the world, as one that provides adequate ideas. The ideas which spring from sense perception are for him inadequate, confused, and mutilated. It is easy to see that also in this world conception there persists the one-sided Platonic way of conceiving an antithesis between perceptions and ideas. The thoughts which are formed independently of perception are alone of value for knowledge. Spinoza goes still further. He extends the antithesis also to the moral feeling and actions of human beings. Feelings of pain can only spring from ideas that stem from perception; such ideas produce desires and passions in man, whose slave he can become if he gives himself over to them. Only what springs from reason produces feelings of unqualified pleasure. The highest bliss of man is therefore his life in the ideas of reason, his devotion to knowledge of the pure world of ideas. Whoever has overcome what stems from the world of perception and lives on only within pure knowledge experiences the highest blessedness.
Not quite a century after Spinoza there appears the Scotsman, David Hume, with a way of thinking that again lets knowledge spring from perception alone. Only individual things in space and time are given. Thinking connects the individual perceptions, not, however because something lies within these perceptions themselves which corresponds to this connecting, but rather because the intellect has habituated itself to bringing things into relationship. The human being is habituated to seeing that one thing follows another in time. He forms for himself the mental picture that it must follow. He makes the first thing into the cause, the second into the effect. The human being is habituated further to seeing that a movement of his body follows upon a thought of his spirit. He explains this to himself by saying that his spirit has caused the movement of his body. Human ideas are habits of thought, nothing more. Only perceptions have reality.
The uniting of the most diverse trends of thought which have come into existence through the centuries is the Kantian world view. Kant also lacks the natural feeling for the relationship between perception and idea. He lives in philosophical preconceptions which he took up into himself through study of his predecessors. One of these preconceptions is that there are necessary truths which are produced by pure thinking free of any experience. The proof of this, in his view, is given by the existence of mathematics and of pure physics which contain such truths. Another of his preconceptions consists of the fact that he denies to experience the ability of attaining equally necessary truths. Mistrust toward the world of perception is also present in Kant. To these habits of thinking there is added the influence of Hume. Kant agrees with Hume with respect to his assertion that the ideas into which thinking combines the individual perceptions do not stem from experience, but rather that thinking adds them to experience. These three preconceptions are the roots of the Kantian thought structure. Man possesses necessary truths. They cannot stem from experience, because it has nothing like them to offer. In spite of this, man applies them to experience. He connects the individual perceptions in accordance with these truths. They stem from man himself. It lies in his nature to bring the things into the kind of relationship which corresponds to the truths gained by pure thinking. Kant goes still further now. He credits the senses also with the ability to bring what is given them from outside into a definite order. This order also does not flow in from outside with the impressions of things. The impressions first receive their order in space and time, through sense perception. Space and time do not belong to the things. The human being is organized in such a way that, when the things make impressions on his senses, he then brings these impressions into spatial or temporal relationships. Man receives from outside only impressions, sensations. The ordering of these in space and in time, the combining of them into ideas, is his own work. But the sensations are also not something that stems from the things. It is not the things that man perceives but only the impressions they make on him. I know nothing about a thing when I have a sensation. I can only say that I notice the arising of a sensation in me. What the characteristics are by which the thing is able to call forth sensations in me, about them I can experience nothing. The human being, in Kant's opinion, does not have to do with the things-in-themselves but only with the impressions which they make upon him and with the relationships into which he himself brings these impressions. The world of experience is not taken up objectively from outside but only, in response to outer causes, subjectively produced from within. It is not the things which give the world of experience the stamp it bears but rather the human organization which does so. That world as such, consequently, is not present at all independently of man. From this standpoint the assumption of necessary truths independent of experience is possible. For these truths relate merely to the way man, of himself, determines his world of experience. They contain the laws of his organization. They have no connection to the things-in-themselves. Kant has therefore found a way out, which permits him to remain in his preconception that there a necessary truths which hold good for the content of the world of experience, without, however, stemming from it. In order to find this way out, he had, to be sure, to commit himself to the view that the human spirit is incapable of knowing anything at all about the things-in-themselves. He had to restrict all knowledge to the world of appearances which the human organization spins out of itself as a result of impressions caused by the things. But why should Kant worry about the being of the things-in-themselves so long as he was able to rescue the eternal, necessarily valid truths in the form in which he pictured them. One-sided Platonism brought forth in Kant a fruit that paralyzes knowledge. Plato turned away from perception and directed his gaze upon the eternal ideas, because perception did not seem to him to express the being of things. Kant, however, renounces the notion that ideas open any real insight into the being of the world, just so they retain the quality of the eternal and necessary. Plato holds to the world of ideas, because he believes that the true being of the world must be eternal, indestructible, unchangeable, and he can ascribe these qualities only to ideas. Kant is content if only he can maintain these qualities for the ideas. Ideas then no longer need to express the being of the world at all.
Kant's philosophical way of picturing things was in addition particularly nourished by the direction of his religious feelings. He did not take as his starting point to look, within the being of man, at the living harmony of the world of ideas and of sense perception but rather posed himself the question: can, through man's experience of the world of ideas, anything be known by him which can never enter the realm of sense perception? Whoever thinks in the sense of the Goethean world view seeks to know the character of the world of ideas as reality, by grasping the being of the idea through his insight into how the Idea allows him to behold reality in the sense-perceptible world of semblance. Then he can ask himself: to what extent, through the character experienced in this way of the world of ideas as reality, can I penetrate into those regions within which the supersensible truths of freedom, of immortality, of the divine world order, find their relationship to human knowledge? Kant negated the possibility of our being able to know anything about the reality of the world of ideas from its relationship to sense perception. From this presupposition he arrived at the scientific result, which, unknown to him, was demanded by the direction of his religious feeling: that scientific knowledge must come to a halt before the kind of questions which relate to freedom, immortality, and the divine world order. There resulted for him the view that human knowledge could only go as far as the boundaries which enclose the sense realm, and that for everything which lies beyond them only faith is possible. He wanted to limit knowing in order to preserve a place for faith. It lies in the sense of the Goethean world view first of all to provide knowing with a firm basis through the fact that the world of ideas, in its essential being, is seen connected with nature, in order then, within the world of ideas thus consolidated, to advance to an experience lying beyond the sense world. Even then, when regions are known which do not lie in the realm of the sense world, one's gaze is still directed toward the living harmony of idea and experience, and certainty of knowledge is sought thereby. Kant could not find any such certainty. Therefore he set out to find, outside of knowledge, a basis for the mental pictures of freedom, immortality, and divine order. It lies in the sense of the Goethean world view to want to know as much about the things-in-themselves as the being of the world of ideas, grasped in connection with nature, allows. It lies in the sense of the Kantian world view to deny to knowledge the right of shining into the world of the things-in-themselves. Goethe wants, within knowledge, to kindle a light which illuminates the being of things. It is also clear to him that the being of the things thus illuminated does not lie within the light itself; but he nevertheless does not want to give up having this being become revealed through the illumination by this light. Kant holds fast to the view that the being of the things illuminated does not lie in the light itself; therefore the light can reveal nothing about this being.
The world view of Kant can stand before that of Goethe only in the sense of the following mental pictures: Kant's world view has not arisen through any clearing away of old errors, nor through any free, original descending into the depths of reality but rather through a fusing together of acquired and inherited philosophical and religious preconceptions. This world view could only spring from an individual in whom the sense for the living creativity within nature has remained undeveloped. And it could only affect the kind of individuals who suffered from the same lack. From the far-reaching influence which Kant's way of thinking exercised upon his contemporaries, one can see how strongly they stood under the spell of one-sided Platonism.