fore
spiritual sins, as such, are of greater guilt.

Reply Obj. 1: Adultery belongs not only to the sin of lust, but also
to the sin of injustice, and in this respect may be brought under the
head of covetousness, as a gloss observes on Eph. 5:5. "No
fornicator, or unclean, or covetous person," etc.; so that adultery
is so much more grievous than theft, as a man loves his wife more
than his chattels.

Reply Obj. 2: The devil is said to rejoice chiefly in the sin of
lust, because it is of the greatest adhesion, and man can with
difficulty be withdrawn from it. "For the desire of pleasure is
insatiable," as the Philosopher states (Ethic. iii, 12).

Reply Obj. 3: As the Philosopher himself says (Ethic. vii, 6), the
reason why it is more shameful to be incontinent in lust than in
anger, is that lust partakes less of reason; and in the same sense he
says (Ethic. iii, 10) that "sins of intemperance are most worthy of
reproach, because they are about those pleasures which are common to
us and irrational animals": hence, by these sins man is, so to speak,
brutalized; for which same reason Gregory says (Moral. xxxi, 17) that
they are more shameful.
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SIXTH ARTICLE [I-II, Q. 73, Art. 6]

Whether the Gravity of a Sin Depends on Its Cause?

Objection 1: It would seem that the gravity of a sin does not depend
on its cause. Because the greater a sin's cause, the more forcibly it
moves to sin, and so the more difficult is it to resist. But sin is
lessened by the fact that it is difficult to resist; for it denotes
weakness in the sinner, if he cannot easily resist sin; and a sin
that is due to weakness is deemed less grievous. Therefore sin does
not derive its gravity from its cause.

Obj. 2: Further, concupiscence is a general cause of sin; wherefore
a gloss on Rom. 7:7, "For I had not known concupiscence," says:
"The law is good, since by forbidding concupiscence, it forbids all
evils." Now the greater the concupiscence by which man is overcome,
the less grievous his sin. Therefore the gravity of a sin is
diminished by the greatness of its cause.

Obj. 3: Further, as rectitude of the reason is the cause of a
virtuous act, so defect in the reason seems to be the cause of sin.
Now the greater the defect in the reason, the less grievous the sin:
so much so that he who lacks the use of reason, is altogether excused
from sin, and he who sins through ignorance, sins less grievously.
Therefore the gravity