  Zabarella moves from the universal and scientific discussion of natural philosophy to a consideration of its particular aspects from the standpoint of operation, not knowledge. Moreover, Zabarella believed that natural philosophy and medicine differ not only in their aims and subject-matters, but also in their methods. The resolutive method is proper to medicine and the compositive method to the philosophy of nature. A physician does not use demonstrations, and if he does, he borrows them from natural philosophy. In medical art the resolutive order of presentation proceeds from knowledge to cure. The end, that is maintaining or recovering health, is broken down into principles, on which the operation is then based. In the order of presentation Zabarella wants to differentiate between the presentation of a whole discipline and that of a part of it. For example, the first part of the art of medicine, physiology, has a compositive order as against the medicine as a whole, which is arranged according to a resolutive order. In Zabarella’s view this shows that physiology does not really belong to medicine at all, but to natural philosophy, because in physiology the nature of a human body is studied apart from operation.