OPAGATION OF MAN AS TO THE BODY
(In Two Articles)

We now consider the propagation of man, as to the body. Concerning
this there are two points of inquiry:

(1) Whether any part of the food is changed into true human nature?

(2) Whether the semen, which is the principle of human generation,
is produced from the surplus food?
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FIRST ARTICLE [I, Q. 119, Art. 1]

Whether Some Part of the Food Is Changed into True Human Nature?

Objection 1: It would seem that none of the food is changed into true
human nature. For it is written (Matt. 15:17): "Whatsoever entereth
into the mouth, goeth into the belly, and is cast out into the privy."
But what is cast out is not changed into the reality of human nature.
Therefore none of the food is changed into true human nature.

Obj. 2: Further, the Philosopher (De Gener. i, 5) distinguishes flesh
belonging to the species from flesh belonging to "matter"; and says
that the latter "comes and goes." Now what is formed from food comes
and goes. Therefore what is produced from food is flesh belonging to
matter, not to the species. But what belongs to true human nature
belongs to the species. Therefore the food is not changed into true
human nature.

Obj. 3: Further, the "radical humor" seems to belong to the reality
of human nature; and if it be lost, it cannot be recovered, according
to physicians. But it could be recovered if the food were changed
into the humor. Therefore food is not changed into true human nature.

Obj. 4: Further, if the food were changed into true human nature,
whatever is lost in man could be restored. But man's death is due
only to the loss of something. Therefore man would be able by taking
food to insure himself against death in perpetuity.

Obj. 5: Further, if the food is changed into true human nature, there
is nothing in man which may not recede or be repaired: for what is
generated in a man from his food can both recede and be repaired. If
therefore a man lived long enough, it would follow that in the end
nothing would be left in him of what belonged to him at the
beginning. Consequently he would not be numerically the same man
throughout his life; since for the thing to be numerically the same,
identity of matter is necessary. But this is incongruous. Therefore
the food is not changed into true human nature.

_On the contrary,_ Augustine says (De Vera Relig. xi): "The bodily
food when corrupted, that is, having lost its fo