In vain did Aristotle resist the Platonic division of the conception of the world. Aristotle saw Nature as a uniform entity containing the ideas as well as sense-perceptible objects and phenomena. Only in the human spirit can the ideas have an independent existence, but in this state of independence they have no reality. Only the soul can separate the idea from the perceptible objects in conjunction with which they constitute reality. If Western Philosophy had adhered to a true understanding of Aristotle's conception, it would have been preserved from a great deal that necessarily appears erroneous to the Goethean view of the world.
But this true understanding of Aristotelianism was at first an inconvenience to many of those who sought to acquire a thought-basis for Christian conceptions. Many of those who considered themselves “Christian” thinkers in the true sense did not know what to make of a conception of Nature that removed the highest active principle into the realm of experience. Many Christian Philosophers and Theologians therefore interpreted Aristotle in a new sense. They attributed to his views a meaning which in their opinion was able to serve as logical support of Christian dogma. — The mind is not intended to seek in the objects for the creative ideas. Truth is communicated to men by God in the form of revelation. Reason is only there to verify what God has revealed. Aristotelian principles were interpreted by the mediaeval Christian thinkers in such a way that the religious doctrine of salvation received its philosophical corroboration from these principles. It is the conception of Thomas Aquinas, the most important of Christian thinkers, that first tries to weave Aristotelian thoughts into the Christian evolution of thought to the extent to which this was possible in his day. According to the conception of Thomas Aquinas, revelation contains the highest truths, the scriptural doctrine of salvation; but it is possible for reason to penetrate into objects in the Aristotelian sense and to extract their ideal content. Revelation descends so far, and reason can rise so high that at a certain point the doctrine of salvation and human knowledge can flow over into each other. Aristotle's mode of penetration into objects becomes, then, the means whereby Thomas Aquinas attains to the sphere of revelation.
With Bacon and Descartes began an era where the will to seek for truth through the inherent power of the human personality asserted itself. Habits of thought had taken such direction that all endeavour ended in setting up views which, in spite of their apparent independence of the preceding Western world-conception, were in fact, only new forms of it. Bacon and Descartes had also acquired a distorted conception of the relation of experience and idea as heritage from a thought-world into which degeneration had entered. Bacon had perception and understanding only for the particulars of Nature. He believed that he arrived at general laws for natural events by gathering together equivalent or rather similar elements from the varied domain of space and time. Goethe speaks of Bacon in these apt words: “For even although he indicates that one should only gather the particulars together for the sake of being able to select from them, to coordinate them, and eventually to arrive at universalities, yet, with him, the particular cases retain undue prominence, and before one is able to arrive at simplification and finality through induction — even such induction as he recommends — life is spent and one's forces are worn out.” For Bacon these general rules are the means whereby reason is able to survey the region of the particulars. But he does not believe that these rules are rooted in the ideal content of the objects and are actual, creative forces of Nature. Therefore he does not directly seek for the idea in the particular, but abstracts it from a multiplicity of particulars. Those who do not believe that the idea lives within the single object will not be disposed to seek for it there. They accept the object as it is offered to external perception pure and simple. Bacon's significance lies in the fact that he pointed to the external mode of perception that has been undervalued by the one-sided form of Platonism already referred to. He emphasised the fact that in this external mode of conception there lies a source of truth. He was not, however, in a position to establish the rights of the world of ideas in relation to the world of perception. He pronounced the ideal to be a subjective element in the human mind. His mode of thinking is an inversion of Platonism. Plato sees reality only in the world of ideas, Bacon only in the world of perception that is free of ideas. In the Baconian conception we have the starting-point of that tendency of thought which still dominates investigators of Nature to-day. This tendency of thought suffers from a false view of the ideal element of the world of experience. It could not come to terms with the view of the Middle Ages that had arisen as the result of a question wrongly put and which led to ideas being regarded as mere names and not realities inherent in things.
Three decades after Bacon we have the views of Descartes, proceeding, it is true, from a different standpoint, but no less influenced by one-sided Platonic modes of thought. Descartes also suffers from the hereditary sin of Western thought, from mistrust in an impartial observation of Nature. Doubt as to the existence of objects, doubt as to whether objects are capable of being cognised is the starting-point of his research. He does not concentrate his gaze on the objects in order to gain access to certainty, but he seeks a tiny door, a bye-way in the truest sense of the word. He withdraws into the most intimate region of thought. “All that I have hitherto believed to be truth may be false,” he says to himself. “My thoughts may be based on illusion. But the one fact remains that I think about the objects. Even if my thought amounts to falsehood and deception, I think, nevertheless. If I think, I also exist. I think, therefore I am.” Descartes believes that he has here obtained a permanent point of departure for all further reflection. He puts another question to himself: Is there not in the content of my thinking still something else that points to true existence? And then he finds the idea of God, as the idea of an All-Perfect Being. As man himself is imperfect how comes it that the idea of an All-Perfect Being is able to enter his world of thought? It is impossible for an imperfect being to produce an idea of this kind out of itself. For the greatest perfection which it is capable of conceiving is still imperfect. This idea must therefore have been put into man by the All-perfect Being himself. God must therefore exist. But how can a perfect Being deceive us by an illusion? The external world which presents itself to us as real must therefore be, in fact, a reality. Otherwise it would be a delusive image imposed on us by the Godhead. In this way Descartes tries to acquire the trust in reality which, as the result of inherited conceptions (Empfindungen), he did not at first possess. He seeks for truth by the most artificial means. He proceeds merely from thought. To thought alone he concedes the power to produce conviction. Conviction in regard to observation can only be acquired when it is imparted by thought. The consequences of this view were that it became the endeavour of Descartes' successors to establish the whole compass of truths which thought is able to evolve out of itself and prove. Their aim was to find the sum-total of all knowledge out of pure reason. They wanted to proceed from the simplest, immediately evident perceptions and to traverse progressively the whole orbit of pure thought. This system was supposed to be built up according to the model of Euclidean Geometry. For it was held that this too proceeds from simple, true premises and evolves its whole content merely by a chain of deduction, without recourse to observation. Spinoza endeavoured to give such a system of reasoned truths in his “Ethics.” He takes a number of conceptions: Substance, Attribute, Mode, Thought, Extension and so forth, and examines their connections and content purely with the reason. The essence of reality is considered to express itself in the thought structure. Spinoza considers that the only knowledge corresponding to the real essence of the universe and yielding adequate ideas is that which exists as a result of this activity that is alien to reality. Ideas derived from sense-perception are to him inadequate, confused, mutilated. It is easy to see the after-effects of the one-sided Platonic view, of the antithesis between perceptions and ideas in these conceptions also. Only those thoughts that are evolved independently of observation have any value for knowledge. Spinoza goes still further. He extends the antithesis to the moral sense and the actions of human beings. Feelings of unhappiness can only spring from ideas derived from sense perception; such ideas generate desires and passions in man, who becomes their slave if he gives himself up to them. Only that which originates from the reason can give birth to feelings of unqualified happiness. Hence the highest bliss of man is life in the ideas of reason, devotion to knowledge of the pure world of ideas. A man who has overcome all that is derived from the world of perception, and yet lives in the realm of pure knowledge, experiences the highest bliss.
Not quite a century after Spinoza there appeared the Scotchman, David Hume, with a mode of thought again assuming knowledge to be derived from perception only. Only single objects in space and time are given. Thought connects the single perceptions together, not, however, because there lies in the objects themselves anything corresponding to such a connection, but because the intellect is accustomed to bringing them into connection. Man is accustomed to see that one thing follows another in time. He forms for himself the idea that there must be sequence. He calls the first, cause; the second, effect. Man is further accustomed to see that a thought in his mind is followed by a movement of his body. He explains this by saying that the mind brings about bodily movement. Man's ideas are habits of thought and nothing more. Perceptions alone have reality.
The combination of the most varied trends of thought that had come into existence through the course of the centuries appears in the Kantian view of the world. Kant also has no natural sense of the relation of perception and idea. He lives in the midst of philosophical preconceptions which he has assimilated from the study of his predecessors. One of these preconceptions is that there exist necessary truths, brought into being by pure thought, free of all element of experience. In Kant's view the proof of this is afforded by the existence of mathematics and pure physics which contain such truths. Another of his preconceptions consists in denying to experience the possibility of attaining to equally necessary truths. Mistrust of the world of perception is present in Kant also. These thought-habits of Kant are further influenced by Hume. Kant admits that Hume is right when the latter asserts that the ideas into which thought unites the single perceptions are not derived from experience but that they are added by thought to experience. These three preconceptions are the basis of the Kantian thought-structure. Man is in possession of essential truths, but these essential truths cannot be derived from experience, because experience has nothing of the kind to offer. Man, however, applies them to experience. He connects the single perceptions in conformity with these truths. They are derived from man himself. It is inherent in his nature to bring things into a connection that is in line with the truths which have been acquired by pure thought. Kant goes still further. He credits the senses also with the capacity for bringing what is imparted to them from without into a definite order. This order does not flow in from outside with the impressions of the objects. The impressions receive spatial and temporal order for the first time through sense-perception. Space and Time do not appertain to the objects. Man is so organised that when the objects make impressions on his senses he brings them into spatial or temporal order. From without man receives impressions, sensations only. Their arrangement in space and in time, their association into ideas is his own work. But neither are the sensations derived from the objects. Man does not become aware of the objects themselves but only of the impression they make upon him. I know nothing about an object when I have a sensation. I can only say I am aware of the appearance of a sensation in myself. I cannot experience the attributes which enable the objects to evoke sensations in me. In Kant's view man has nothing to do with the things-in-themselves, but only with the impression they make upon him and with the connections into which he himself brings these impressions. The realm of experience is not received objectively, from without, but is only instigated from without; it is produced subjectively from within. The character it bears is not imparted to it by the objects but by the organisation of man. It has therefore no existence per se apart from man. From this point of view the postulation of essential truths — truths that are independent of experience — is possible. For these truths are related merely to the way in which man determines his world of experience from out of himself. They contain the laws of his constitution. They have no relation to things-in-themselves. Kant, then, has found a way out which enables him to adhere to his preconception that there are essential truths which hold good for the content of the world of experience without being derived therefrom. In order to discover this way out he had, of course, to decide in favour of the view that the human mind is incapable of knowing anything about things-in-themselves. He had to limit all knowledge to the phenomenal world which the human organisation weaves out of itself as the result of the impressions produced by the objects. Why should Kant trouble about the essential being of the thing-in-itself if he could only preserve the eternal, necessary truths in the sense in which he conceived of them? One-sided Platonism produced in Kant a harvest that is paralysing to knowledge. Plato turned away from perception and directed his gaze to the eternal ideas, because it seemed to him that perception did not make manifest the essence of the objects. Kant, however, renounces the conception that the ideas open up a true insight into the essential being of the universe if only there remains to them the attribute of eternity and necessity. Plato adheres to the world of ideas because of his belief that the true being of the universe must be eternal, imperishable, unchangeable, and because he can ascribe these attributes only to the ideas. Kant is content with merely predicting these attributes of the ideas. They need not then any longer express the essential being of the universe.
Kant's philosophical mode of conception was nourished in a yet higher degree by the trend of his religious sense. He did not proceed from vision of the living harmony of the world of ideas and sense-perception in the being of man, but he put this question to himself: Can anything be cognised by man, as the result of experience of the world of ideas that can never enter into the realm of sense perception? A man who thinks in the Goethean sense seeks to cognise the world of ideas in its real nature by apprehending the essential being of the idea, realising how this allows reality to be perceived in the world of sense-appearance. Then he may ask himself: To what extent does this experience of the real character of the world of ideas enable me to penetrate into the region wherein the relationship of the supersensible truths of Freedom, of Immortality, of the Divine World Order to human knowledge is discovered? Kant denies that it is possible to cognise anything about the reality of the world of ideas from its relationship to sense-perception. Out of this assumption there arose for him, as a scientific result, that which, unconsciously to him, was demanded by the trend of his religious sense: that scientific cognition must come to a standstill before problems which concern Freedom, Immortality, and the Divine World Order. It followed that, for him, human cognition can only reach to the boundaries enclosing the realm of sense and that in reference to everything that lies beyond faith alone is possible. He wanted to set bounds to cognition in order to preserve a place for faith. It inheres in the character of the Goethean world-conception first to provide knowledge with a firm foundation as the result of perceiving in Nature the world of ideas in its true being, in order hereafter, within this world of ideas, to proceed to experience lying outside the sense world. Even when regions are cognised which do not lie within the realm of the sense world, the gaze is directed to the living harmony of idea and experience, and certainty of knowledge is sought as a result of this. Kant could discover no such certainty. He therefore set out to discover, beyond knowledge, a foundation for the conceptions of Freedom, of Immortality and of the Divine World Order. Inherent in the character of the Goethean world-conception is the desire to know as much of the “things-in-themselves” as is permitted by the comprehension of the true being of the world of ideas within Nature. The nature of the Kantian world-conception makes it deny to knowledge the claim of being able to illuminate the world of the “things-in-themselves.” Goethe wants to kindle in knowledge a light that will illuminate the true essence of the objects. He realises that the true essence of the objects so illuminated does not lie in the light, but in spite of this he maintains that this true essence may become manifest as a result of the illumination. Kant insists that the true essence of the illuminated objects does not inhere in the light; the light therefore can reveal nothing of this true essence.
The Kantian world-conception can only appear to Goethe's in the following light: the Kantian world-conception has not arisen as the result of the removal of old errors, nor of a free, original penetration into reality, but as the result of a logical interblending of acquired and inherited philosophical and religious preconceptions. It could only emanate from a mind where the sense of the living, creative activity in Nature has remained in an undeveloped condition. And it could only influence minds that also suffered from the same defect. The far-reaching influence which Kant's mode of thought exercised on his contemporaries proves to what an extent they were living under the ban of a one-sided Platonism.