"What does not bar numerical unity in a man while he lives on uninterruptedly (writes St. Thomas), clearly can be no bar to the identity of the arisen man with the man that was. In a man's body, while he lives, there are not always the same parts in respect of matter but only in respect of species. In respect of matter there is a flux and reflux of parts. Still that fact does not bar the man's numerical unity from the beginning to the end of his life. The form and species of the several parts continue throughout life, but the matter of the parts is dissolved by the natural heat, and new matter accrues through nourishment. Yet the man is not numerically different by the difference of his component parts at different ages, although it is true that the material composition of the man at one stage of his life is not his material composition at another. Addition is made from without to the stature of a boy without prejudice to his identity, for the boy and the adult are numerically the same man." In a word, Aquinas says that we recognize that the body of the boy and of the man are the same though they are composed of quite different material. With this in mind the problem of the Resurrection takes on quite a new aspect from what it held before. What we would call attention to, however, is not so much the matter of the argument as the mode of it. It is essentially modern in every respect. Not only does Thomas know that the body changes completely during the course of years, but he knows that the agent by which the matter of the parts is dissolved is "the natural heat," while "new matter accrues through nourishment." The passage contains a marvelous anticipation of present-day physiology as well as a distinct contribution to Christian apologetics. This coordination of science and theology, though usually thought to be lacking among scholastic philosophers, is constantly typical of their mode of thought and discussion, and this example, far from {279} being exceptional, is genuinely representative of them, as all serious students of scholasticism know.