The determination of the concept of art as pure intuition would be little more than a verbal variation of older doctrines, if its validity and importance could not be proved in the actual practice of thought on æsthetic problems, in the study of the relations of the æsthetic fact with the other facts of human activity, and in the criticism of errors which have invaded the field of æsthetic thought through a confusion of the æsthetic with the intellectual or the practical. We shall therefore not be able to grasp the new concept in the fulness of its meaning until we have surveyed the whole ground of the philosophy of mind: the æsthetic concept cannot be said to be fully determined until we have a clear conception of the other fundamental grades or forms of the spirit. For the purposes of our exposition, we may however anticipate a summary or scheme of the essential relations, which will be more fully developed in the following chapters. We have already seen how the logical activity springs from the soil of the pure intuition; how the knowledge of the universal follows the knowledge of the individual. The æsthetic and the logic grade, of which the second implies the first, exhaust the whole of knowledge, the whole theoretical life of man. A third grade or form does not exist: not in history, which Croce still considered, in the first years of this period, as reducible to the concept of art, and differentiated from it only by its employment of the predicate of existence, of the distinction between reality and imagination; and not in the natural and mathematical sciences, which elaborate the data of intuition through fictions, hypotheses, and conventions, which are practical and not theoretical processes.