Aquinas avoids the difficulties and contradictions of the "two substance " theory and, saving the personality, accounts for the observed facts of the unity of consciousness.His doctrine : The particular creation of the soul is a corollary of the foregoing. 3 (in refutation of the opinion of Pythagoras, Plato and Origen — with whom Leibniz might be grouped as professing a modified form of the same opinion—the creation of souls at the beginning of time ).This signifies no more than that, in the system of classification and definition shown in the Arbor Porphyriana , man is a substance, corporeal, living, sentient, and rational.
B This doctrine is obviously to be looked for in all Catholic theology. As to the mode of creation, there would seem to be two possible alternatives. 2, ad 2um), a succession of preparatory forms preceded information by the rational soul, it nevertheless follows necessarily from the established principles of Scholasticism that this, not only in the case of the first man, but of all men, must be produced in being by a special creative act.Though strictly speaking self-contradictory, the phrase expresses in a convenient form the abiding reciprocity of relation between these two "principles of substantial being". In Greek and in modern philosophy, as well as during the Patristic and Scholastic periods, another celebrated theory laid claim to pre-eminence. It is in a non-natural state of union, and longs to be freed from its bodily prison (cf. Plato has recourse to a theory of a triple soul to explain the union—a theory that would seem to make personality altogether impossible (see MATTER). Augustine, following him (except as to the triple-soul theory) makes the "body" and " soul " two substances; and man "a rational soul using a mortal and earthly body" (De Moribus, I, xxvii).