The metaphor which Locke constantly uses is the clew to his conception of innate ideas. They are characters stamped or imprinted upon the mind, they exist _in_ the mind. The mind would be just what it is, even if they had no existence. It would not have quite so much "in" it, but its own nature would not be changed. Innate ideas he conceives as bearing a purely external relation to mind. They are not organic to it, nor necessary instruments through which it expresses itself; they are mechanically impressed upon it. But what the "intellectual" school had meant by innate ideas was precisely that the relation of ideas to intelligence is _not_ that of passive holding or containing on the side of mind, and of impressions or stamps on the side of the ideas. Locke reads the fundamental category of empiricism--mechanical relation, or external action--into the nature of innate ideas, and hence easily infers their absurdity. But the object of the upholders of innate ideas had been precisely to deny that this category was applicable to the whole of intelligence. By an innate idea they meant an assertion of the dynamic relation of intelligence and some of its ideas. They meant to assert that intelligence has a structure, which necessarily functions in certain ways. While Locke's highest conception of an innate idea was that it must be something ready made, dwelling in the mind prior to experience, Leibniz everywhere asserts that it is a connection and relation which forms the logical prius and the psychological basis of experience. He finds no difficulty in admitting all there is of positive truth in Locke's doctrine; namely, that we are not conscious of these innate ideas until a period later than that in which we are conscious of sensible facts, or, in many cases, are not conscious of them at all. This priority in time of sensible experience to rational knowledge, however, can become a reason for denying the "innate" character of the latter only when we suppose that they are two entirely different orders of fact, one knowledge due to experience, the other knowledge already formed and existing in the mind prior to "experience."