So far, we have determined the idea of knowledge. This idea is given immediately in the human consciousness whenever it functions cognitively. To the "Ego," as the centre [49] of consciousness, are given immediately external and internal perceptions, as well as its own existence. The Ego feels impelled to find more in the Given than it immediately contains. Over against the given world, a second world, the world of thinking, unfolds itself for the Ego and the Ego unites these two by realising, of its own free will, the idea of knowledge which we have determined. This accounts for the fundamental difference between the way in which in the objects of human consciousness itself the concept and the Immediately-Given unite to form Reality in its wholeness, and the way in which their union obtains in the rest of the world-content. For every other part of the world-content we must assume that the union of the two factors is original and necessary from the first, and that it is only for cognition, when cognition begins, that an artificial separation has supervened, but that cognition in the end undoes the separation in keeping with the original and essential unity of the object-world. For consciousness the case is quite otherwise. Here the union exists only when it is achieved by the living activity of consciousness itself. With every other kind of object, the separation of the two factors is significant, not for the object, but only for knowledge. Their union is here original, their separation derivative. Cognition effects a separation only because it must first separate before it can achieve union by its own methods. But, for consciousness, the Concept and the Given are originally separate. Union is here derivative, and that is why cognition has the character which we have described. Just because in consciousness Idea and Given appear in separation, does the whole of reality split itself for consciousness into these two factors. And, again, just because consciousness can bring about the union of the two factors only by its own activity, can it reach full reality only by performing the act of cognition. The remaining categories (ideas) would be necessarily united with the corresponding lands of the Given, even if they were not taken up into cognition. But the idea of cognition can be united with the Given which corresponds to it, only by the activity of consciousness. Real consciousness exists only in realising itself. With these remarks we believe ourselves to be sufficiently equipped for laying bare the root-error of Fichte's Wissenschaftslehre and, at the same time, for supplying the key to the understanding of it. Fichte is among all Kant's successors the one who has felt most vividly that nothing but a theory of consciousness can supply the foundation for all the sciences. But he never clearly understood why this is so. He felt that the act which we have called the second step in the Theory of Knowledge and which we have formulated as a