: for even
if it is less difficult for him to persist, yet he persists in the
more perfect good. Wherefore such like perseverance may be a virtue,
because virtue derives perfection from the aspect of good rather than
from the aspect of difficulty.

Reply Obj. 2: Sometimes a virtue and its act go by the same name:
thus Augustine says (Tract. in Joan. lxxix): "Faith is to believe
without seeing." Yet it is possible to have a habit of virtue without
performing the act: thus a poor man has the habit of magnificence
without exercising the act. Sometimes, however, a person who has the
habit, begins to perform the act, yet does not accomplish it, for
instance a builder begins to build a house, but does not complete it.
Accordingly we must reply that the term "perseverance" is sometimes
used to denote the habit whereby one chooses to persevere, sometimes
for the act of persevering: and sometimes one who has the habit of
perseverance chooses to persevere and begins to carry out his choice
by persisting for a time, yet completes not the act, through not
persisting to the end. Now the end is twofold: one is the end of the
work, the other is the end of human life. Properly speaking it
belongs to perseverance to persevere to the end of the virtuous work,
for instance that a soldier persevere to the end of the fight, and
the magnificent man until his work be accomplished. There are,
however, some virtues whose acts must endure throughout the whole of
life, such as faith, hope, and charity, since they regard the last
end of the entire life of man. Wherefore as regards these which are
the principal virtues, the act of perseverance is not accomplished
until the end of life. It is in this sense that Augustine speaks of
perseverance as denoting the consummate act of perseverance.

Reply Obj. 3: Unchangeable persistence may belong to a virtue in two
ways. First, on account of the intended end that is proper to that
virtue; and thus to persist in good for a long time until the end,
belongs to a special virtue called perseverance, which intends this
as its special end. Secondly, by reason of the relation of the habit
to its subject: and thus unchangeable persistence is consequent upon
every virtue, inasmuch as virtue is a "quality difficult to change."
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SECOND ARTICLE [II-II, Q. 137, Art. 2]

Whether Perseverance Is a Part of Fortitude?

Objection 1: It seems that perseverance is not a part of fortitude.
For, a