Part 1476

ed above (A[1]; Q[118], A[1]). For if human nature has a virtue for the communication of its form to alien matter not only in another, but also in its own subject; it is clear that the food which at first is dissimilar, becomes at length similar through the form communicated to it. Now it belongs to the natural order that a thing should be reduced from potentiality to act gradually: hence in things generated we observe that at first each is imperfect and is afterwards perfected. But it is clear that the common is to the proper and determinate, as imperfect is to perfect: therefore we see that in the generation of an animal, the animal is generated first, then the man or the horse. So therefore food first of all receives a certain common virtue in regard to all the parts of the body, which virtue is subsequently determinate to this or that part.

Now it is not possible that the semen be a kind of solution from what is already transformed into the substance of the members. For this solution, if it does not retain the nature of the member it is taken from, it would no longer be of the nature of the begetter, and would be due to a process of corruption; and consequently it would not have the power of transforming something else into the likeness of that nature. But if it retained the nature of the member it is taken from, then, since it is limited to a certain part of the body, it would not have the power of moving towards (the production of) the whole nature, but only the nature of that part. Unless one were to say that the solution is taken from all the parts of the body, and that it retains the nature of each part. Thus the semen would be a small animal in act; and generation of animal from animal would be a mere division, as mud is generated from mud, and as animals which continue to live after being cut in two: which is inadmissible.

It remains to be said, therefore, that the semen is not something separated from what was before the actual whole; rather is