With some, the first phase is long and fully conscious; in others it seems negligible, equal to zero--there is nothing of it because there exists a natural or acquired tendency toward equilibrium. "For a long time," says Schumann, "I had the habit of racking my brain, and now I scarcely need to scratch my forehead. Everything runs naturally."[74] The second phase is almost the same in both cases: it is only an instant, but it is essential--it is the moment of imaginative synthesis. Lastly, the third phase is very short for some, because the main labor is already done, and there remains only the finishing touch or the verification. It is long for others, because they must pass from the perceived idea to complete realization, and because the preparatory work is faulty; so that for these the second creative process is shortened in appearance only. Such seem to me the two principal forms of the mechanism of creation. These are genera; they include species and varieties that a patient and minute study of the processes peculiar to various inventors would reveal to us. We must bear in mind that this work makes no claim of being a monograph on invention, but merely a sketch.[75] The two processes above described seem to correspond on the whole to the oft-made distinction between the intuitive or spontaneous, and the combining or reflective imagination. The intuitive, essentially synthetic form, is found principally in the purely imaginative types, children and savages. The mind proceeds from the whole to details. The generative idea resembles those concepts which, in the sciences, are of wide range because they condense a generalization rich in consequences. The subject is at first comprehended as a whole; development is organic, and we may compare it to the embryological process that causes a living being to arise from the fertilized ovum, analogous to an immanent logic. As a type of this creative form there has often been given a letter wherein Mozart explains his mode of conception. Recently (and that is why I do not reprint it here) it has been suspected of being apocryphal. I regret this--it was worthy of being authentic. According to Goethe, Shakespeare's _Hamlet_ could have been created only through an intuitive process, etc.