's
nature, in so far as it is contrary to the order of reason.

Reply Obj. 1: Although the virtues are not caused by nature as
regards their perfection of being, yet they incline us to that which
accords with reason, i.e. with the order of reason. For Cicero says
(De Inv. Rhet. ii) that "virtue is a habit in accord with reason,
like a second nature": and it is in this sense that virtue is said to
be in accord with nature, and on the other hand that vice is contrary
to nature.

Reply Obj. 2: The Philosopher is speaking there of a thing being
against nature, in so far as "being against nature" is contrary to
"being from nature": and not in so far as "being against nature" is
contrary to "being in accord with nature," in which latter sense
virtues are said to be in accord with nature, in as much as they
incline us to that which is suitable to nature.

Reply Obj. 3: There is a twofold nature in man, rational nature, and
the sensitive nature. And since it is through the operation of his
senses that man accomplishes acts of reason, hence there are more who
follow the inclinations of the sensitive nature, than who follow the
order of reason: because more reach the beginning of a business than
achieve its completion. Now the presence of vices and sins in man is
owing to the fact that he follows the inclination of his sensitive
nature against the order of his reason.

Reply Obj. 4: Whatever is irregular in a work of art, is unnatural to
the art which produced that work. Now the eternal law is compared to
the order of human reason, as art to a work of art. Therefore it
amounts to the same that vice and sin are against the order of human
reason, and that they are contrary to the eternal law. Hence
Augustine says (De Lib. Arb. iii, 6) that "every nature, as such, is
from God; and is a vicious nature, in so far as it fails from the
Divine art whereby it was made."
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THIRD ARTICLE [I-II, Q. 71, Art. 3]

Whether Vice Is Worse Than a Vicious Act?

Objection 1: It would seem that vice, i.e. a bad habit, is worse than
a sin, i.e. a bad act. For, as the more lasting a good is, the better
it is, so the longer an evil lasts, the worse it is. Now a vicious
habit is more lasting than vicious acts, that pass forthwith.
Therefore a vicious habit is worse than a vicious act.

Obj. 2: Further, several evils are more to be shunned than one. But a
bad habit is virtually the cause of many bad acts. Therefore a
vic