While all apperceptions agree in the objective characteristics of the combination of a complex into a unity and in the subjective one of voluntary activity, yet in a further comparison of our thought processes we meet with a very evident difference in the content of the combined ideas. Think, for example, of a sentence such as the following one from Kant: "Whether the treatment of knowledge, that belongs to a critique of reason, is proceeding along the sure way of science or not, can easily be judged by the result." If we compare this sentence out of the Critique of Pure Reason with the above description, out of _Wilhelm Meister_, may we not be inclined to say that each belongs to quite a different world of thought? In our first example everything is graphic, each word represents a sensuous idea, the whole is a picture in words. In Kant not one single word is the expression of a concrete object, they are all abstract concepts, which only obtain some living content by means of further processes of thought, which they stimulate. And yet the abstract thought-compound corresponds with the concrete description in so far as it can be reduced ultimately to concrete concepts. It has to make use of words, which as impressions of the senses of hearing and seeing are themselves sensuous ideas. Certainly such concepts as "knowledge," "reason," "science," and even "treatment," "way," "result," which make up the sentence out of Kant, are not in the least of a concrete character in the way they are used. But if we go back to the original meanings of all these words, we find every time that it is a sensuous one, i.e. relates to the senses. "Treatment" at an earlier stage of language means something that we can treat in a material sense, "knowledge" refers to sensuous knowledge --something that we know by means of our senses, "reason" is nothing but the understanding of words or similar sensible impressions. As regards "way" it clearly bears the stamp of a concrete concept, it can be used as synonymous with "road." And yet in all these cases, the words in the thought, which they here help to express, are far removed from their origins. Thus the most abstract thought can ultimately be reduced in all its components to concrete concepts. And these words, the means of expression, which we cannot dispense with, at the same time bear witness to the fact that abstract thinking has developed itself step by step from concrete. The history of knowledge teaches us that this happened in the following manner. The original sensuous ideas entered into the most manifest relations with each other, and then just as at the primitive stage of thought the concrete ideas themselves were joined together as separate elements of one thought, so at a higher stage these relations between ideas were then treated as elements. So the word "knowledge" represents an almost unlimited number of processes of objective knowing, and thereby it becomes an abstract concept,