I-II, Q. 55, Art. 3]

Whether Human Virtue Is a Good Habit?

Objection 1: It would seem that it is not essential to virtue that it
should be a good habit. For sin is always taken in a bad sense. But
there is a virtue even of sin; according to 1 Cor. 15:56: "The virtue
[Douay: 'strength'] of sin is the Law." Therefore virtue is not
always a good habit.

Obj. 2: Further, Virtue corresponds to power. But power is not only
referred to good, but also to evil: according to Isa. 5: "Woe to you
that are mighty to drink wine, and stout men at drunkenness."
Therefore virtue also is referred to good and evil.

Obj. 3: Further, according to the Apostle (2 Cor. 12:9): "Virtue
[Douay: 'power'] is made perfect in infirmity." But infirmity is an
evil. Therefore virtue is referred not only to good, but also to evil.

_On the contrary,_ Augustine says (De Moribus Eccl. vi): "No one can
doubt that virtue makes the soul exceeding good": and the Philosopher
says (Ethic. ii, 6): "Virtue is that which makes its possessor good,
and his work good likewise."

_I answer that,_ As we have said above (A. 1), virtue implies a
perfection of power: wherefore the virtue of a thing is fixed by the
limit of its power (De Coelo i). Now the limit of any power must
needs be good: for all evil implies defect; wherefore Dionysius says
(Div. Hom. ii) that every evil is a weakness. And for this reason the
virtue of a thing must be regarded in reference to good. Therefore
human virtue which is an operative habit, is a good habit, productive
of good works.

Reply Obj. 1: Just as bad things are said metaphorically to be
perfect, so are they said to be good: for we speak of a perfect thief
or robber; and of a good thief or robber, as the Philosopher explains
(Metaph. v, text. 21). In this way therefore virtue is applied to
evil things: so that the "virtue" of sin is said to be law, in so far
as occasionally sin is aggravated through the law, so as to attain to
the limit of its possibility.

Reply Obj. 2: The evil of drunkenness and excessive drink, consists
in a falling away from the order of reason. Now it happens that,
together with this falling away from reason, some lower power is
perfect in reference to that which belongs to its own kind, even in
direct opposition to reason, or with some falling away therefrom. But
the perfection of that power, since it is compatible with a falling
away from reason, cannot be called a human virtue.

Reply Obj. 3: R