The upper limit of intuitive knowledge is given by reflected, or intellectual, or logical knowledge, or whatever we may call that which is no longer knowledge of the individual, of things, but of the universal, of relations among things, of concepts. Intuitive knowledge is independent of intellectual knowledge, as it is possible to form intuitions without forming concepts; in the examples which I have given in the preceding paragraph, practically all the intuitions are pure intuitions, in the sense that they do not contain any logical ingredients. But even when such are found, they appear as mere intuitions, and not as concepts: as, for instance, Hamlet's philosophy, which I do not read as a help towards the understanding of metaphysical problems, but as a characterization of an imaginery individual. On the other hand, logical knowledge is founded on intuitions, presupposes the world of intuitions as its matter or content. The relation between æsthetic and logical knowledge is one of grade or development: the former stands by itself, rests directly on that which is not yet spirit or form, is the first grade of spiritual or human activity; the latter gives a further spiritual elaboration to the intuitive material. This relationship, to which we shall return later, is the typical process of Croce's own logic, the logic of spiritual or mental grades, which he substitutes throughout his system for the naturalistic or transcendental logic of his early masters. A further step in the deduction of the concept of intuitive or æsthetic knowledge, is made by identifying intuition with expression. Given the active and conscious character of intuition, we are already prepared to admit that every true intuition is at the same time an expression; that which cannot objectify itself into an expression is nothing but mere sensation. The mind does not actually intuit except by doing, forming, and expressing. We must not think only of verbal expressions: there are intuitions which cannot be expressed by words, but only by sounds or lines or colours. But in any case the two words are interchangeable: what really exists in our spirit is only what we can express. It is only when we can express ourselves, that we are conscious of actually possessing, that is, of having actually formed, our intuitions. It is impossible to distinguish the expression from the intuition because they are not two but one.