If we wish to regard the world in the light of the "thing itself," we shall easily see that the world "itself" and the world as it appears, the world of phenomena, differ only in the same way in which the whole differs from its component parts. The world "itself" is nothing else but the sum total of its phenomena. The same holds good of that part of the world phenomena which we call reason, spirit, faculty of thought. Although we distinguish between the faculty of thought and its phenomena or manifestations, yet the faculty of thought "itself," or "pure" reason, exists in reality only in the sum total of its manifestations. Seeing is the physical existence of the faculty of sight. We possess the whole only by means of its parts, and we can possess reason, like all other things, only by the help of its effects, by its various thoughts. But we repeat that reason does not precede thought in the order of time. On the contrary thoughts generated by perceptible objects serve as a basis for the development of the concept of the faculty of thought. Just as the understanding of the world movements has taught us that the sun is not revolving around the earth, so the understanding of the thought process tells us that it is not the faculty of thought which creates thought, but vice versa, that the concept of this faculty is created out of a series of concrete thoughts. Hence the faculty of thought practically exists only as the sum total of our thoughts, just as the faculty of sight exists only through the sum of the things that we see. These thoughts, this practical reason, serve as the material out of which our brain manufactures the concept of "pure" reason. Reason is necessarily impure in practice, which means that it must connect itself with some object. Pure reason, or abstract reason without any special content, cannot be anything else but the general characteristic of all concrete reasoning processes. We possess this general nature of reason in two ways: In an impure state, that is as practical and concrete phenomenon, consisting of the sum of our real perceptions, and in a pure state, that is theoretically or abstractly, in the concept. The phenomenon of reason is distinguished from reason "itself" just as the real animals are distinguished from the concept of the animal.