virtue. But the flesh cannot be the
subject of virtue: for the Apostle says (Rom. 7:18): "I know that
there dwelleth not in me, that is to say, in my flesh, that which is
good." Therefore the flesh cannot be the subject of original sin, but
only the soul.

_I answer that,_ One thing can be in another in two ways. First, as
in its cause, either principal, or instrumental; secondly, as in its
subject. Accordingly the original sin of all men was in Adam indeed,
as in its principal cause, according to the words of the Apostle
(Rom. 5:12): "In whom all have sinned": whereas it is in the bodily
semen, as in its instrumental cause, since it is by the active power
of the semen that original sin together with human nature is
transmitted to the child. But original sin can nowise be in the flesh
as its subject, but only in the soul.

The reason for this is that, as stated above (Q. 81, A. 1), original
sin is transmitted from the will of our first parent to this
posterity by a certain movement of generation, in the same way as
actual sin is transmitted from any man's will to his other parts. Now
in this transmission it is to be observed, that whatever accrues from
the motion of the will consenting to sin, to any part of man that can
in any way share in that guilt, either as its subject or as its
instrument, has the character of sin. Thus from the will consenting
to gluttony, concupiscence of food accrues to the concupiscible
faculty, and partaking of food accrues to the hand and the mouth,
which, in so far as they are moved by the will to sin, are the
instruments of sin. But that further action is evoked in the
nutritive power and the internal members, which have no natural
aptitude for being moved by the will, does not bear the character of
guilt.

Accordingly, since the soul can be the subject of guilt, while the
flesh, of itself, cannot be the subject of guilt; whatever accrues to
the soul from the corruption of the first sin, has the character of
guilt, while whatever accrues to the flesh, has the character, not of
guilt but of punishment: so that, therefore, the soul is the subject
of original sin, and not the flesh.

Reply Obj. 1: As Augustine says (Retract. i, 27) [*Cf. QQ. lxxxiii,
qu. 66], the Apostle is speaking, in that passage, of man already
redeemed, who is delivered from guilt, but is still liable to
punishment, by reason of which sin is stated to dwell "in the flesh."
Consequently it follows that the flesh is