which are under our control: since by nature some are
mentally deficient, and some shrewd-minded. Therefore no sin is in
the reason.

_On the contrary,_ Augustine says (De Trin. xii, 12) that sin is in
the lower and in the higher reason.

_I answer that,_ The sin of any power is an act of that power, as we
have clearly shown (AA. 1, 2, 3). Now reason has a twofold act: one
is its proper act in respect of its proper object, and this is the
act of knowing the truth; the other is the act of reason as directing
the other powers. Now in both of these ways there may be sin in the
reason. First, in so far as it errs in the knowledge of truth, which
error is imputed to the reason as a sin, when it is in ignorance or
error about what it is able and ought to know: secondly, when it
either commands the inordinate movements of the lower powers, or
deliberately fails to check them.

Reply Obj. 1: This argument considers the defect in the proper act of
the reason in respect of its proper object, and with regard to the
case when it is a defect of knowledge about something which one is
unable to know: for then this defect of reason is not a sin, and
excuses from sin, as is evident with regard to the actions of madmen.
If, however, the defect of reason be about something which a man is
able and ought to know, he is not altogether excused from sin, and
the defect is imputed to him as a sin. The defect which belongs only
to the act of directing the other powers, is always imputed to reason
as a sin, because it can always obviate this defect by means of its
proper act.

Reply Obj. 2: As stated above (Q. 17, A. 1), when we were treating of
the acts of the will and reason, the will moves and precedes the
reason, in one way, and the reason moves and precedes the will in
another: so that both the movement of the will can be called
rational, and the act of the reason, voluntary. Accordingly sin is
found in the reason, either through being a voluntary defect of the
reason, or through the reason being the principle of the will's act.

The Reply to the Third Objection is evident from what has been said
(ad 1).
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SIXTH ARTICLE [I-II, Q. 74, Art. 6]

Whether the Sin of Morose Delectation Is in the Reason?

Objection 1: It would seem that the sin of morose delectation is not
in the reason. For delectation denotes a movement of the appetitive
power, as stated above (Q. 31, A. 1). But the appetitive power is
distinc