 As to the problem of the relation of soul to body, Paul rejects the Augustinian conception and follows the Aristotelian view of the soul as form of the body, so that in his opinion the subject of knowledge is not the soul alone, but the whole human composite. Not even sensation can be attributed simply to the soul using a body, as Augustine had thought. Moreover, against Aristotle and following Aquinas, Paul claims that, although it is the form of the body, the human soul is a self-subsistent form, and therefore incorruptible. However, unlike Aquinas, he maintains that the human soul is two-fold, as the complete human soul (anima totalis) derives from the close union of two distinct principles, the cogitative and the intellective. This fact does not break the unity of the human soul nor of the human composite, since (1) the cogitative principle is the cause of the animality and the intellective one of the rationality of man; (2) neither of them can exist in man without the other; and (3) the cogitative soul is in potency in relation to the intellective one (Summa philosophiae naturalis, ed. Venetiis 1503 [= SN], pars v, ch. 5, fols. 68vb and 69ra; see also Scriptum super libros De anima ed. Venetiis 1504 [= In De an.], II, t.c. 23, fols. 47rb-48ra).