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some part of the body; while in the semen there is not even a
particle of the body, because there is not a particle of the body
which is not made from the semen and by the power thereof. Therefore
the sensitive soul is not produced through the semen.

Obj. 4: Further, if there be in the semen any principle productive of
the sensitive soul, this principle either remains after the animal is
begotten, or it does not remain. Now it cannot remain. For either it
would be identified with the sensitive soul of the begotten animal;
which is impossible, for thus there would be identity between
begetter and begotten, maker and made: or it would be distinct
therefrom; and again this is impossible, for it has been proved above
(Q. 76, A. 4) that in one animal there is but one formal principle,
which is the soul. If on the other hand the aforesaid principle does
not remain, this again seems to be impossible: for thus an agent
would act to its own destruction, which cannot be. Therefore the
sensitive soul cannot be generated from the semen.

_On the contrary,_ The power in the semen is to the animal seminally
generated, as the power in the elements of the world is to animals
produced from these elements--for instance by putrefaction. But in
the latter animals the soul is produced by the elemental power,
according to Gen. 1:20: "Let the waters bring forth the creeping
creatures having life." Therefore also the souls of animals seminally
generated are produced by the seminal power.

_I answer that,_ Some have held that the sensitive souls of animals
are created by God (Q. 65, A. 4). This opinion would hold if the
sensitive soul were subsistent, having being and operation of itself.
For thus, as having being and operation of itself, to be made would
needs be proper to it. And since a simple and subsistent thing cannot
be made except by creation, it would follow that the sensitive soul
would arrive at existence by creation.

But this principle is false--namely, that being and operation are
proper to the sensitive soul, as has been made clear above (Q. 75,
A. 3): for it would not cease to exist when the body perishes. Since,
therefore, it is not a subsistent form, its relation to existence is
that of the corporeal forms, to which existence does not belong as
proper to them, but which are said to exist forasmuch as the
subsistent composites exist through them.

Wherefore to be made is proper to composites. And since the generator
i