Reply Obj. 2:  The parts which are assigned to each cardinal virtue, are not integral parts that combine to form a whole; but subjective or potential parts, as we shall explain further on (Q. 57, A. 6, ad 4; II-II, Q. 48).

Reply Obj. 3:  In any science, he who acquires, by demonstration, scientific knowledge of one conclusion, has the habit indeed, yet imperfectly.  And when he obtains, by demonstration, the scientific knowledge of another conclusion, no additional habit is engendered in him:  but the habit which was in him previously is perfected, forasmuch as it has increased in extent; because the conclusions and demonstrations of one science are coordinate, and one flows from another. ________________________

TREATISE ON HABITS IN PARTICULAR (QQ. 55-89): 
GOOD HABITS, i.e., VIRTUES (QQ. 55-70)
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QUESTION 55

OF THE VIRTUES, AS TO THEIR ESSENCE
(In Four Articles)

We come now to the consideration of habits specifically.  And since habits, as we have said (Q. 54, A. 3), are divided into good and bad, we must speak in the first place of good habits, which are virtues, and of other matters connected with them, namely the Gifts, Beatitudes and Fruits; in the second place, of bad habits, namely of vices and sins.  Now five things must be considered about virtues:  (1) the essence of virtue; (2) its subject; (3) the division of virtue; (4) the cause of virtue; (5) certain properties of virtue.

Under the first head, there are four points of inquiry: 

(1) Whether human virtue is a habit?

(2) Whether it is an operative habit?

(3) Whether it is a good habit?

(4) Of the definition of virtue.
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FIRST ARTICLE [I-II, Q. 55, Art. 1]

Whether Human Virtue Is a Habit?

Objection 1:  It would seem that human virtue is not a habit:  For virtue is “the limit of power” (De Coelo i, text. 116).  But the limit of anything is reducible to the genus of that of which it is the limit; as a point is reducible to the genus of line.  Therefore virtue is reducible to the genus of power, and not to the genus of habit.

Obj. 2:  Further, Augustine says (De Lib.  Arb. ii) [Retract. ix; cf.  De Lib.  Arb. ii, 19] that “virtue is good use of free-will.”  But use of free-will is an act.  Therefore virtue is not a habit, but an act.

Obj. 3:  Further, we do not merit by our habits, but by our actions:  otherwise a man would merit continually, even while asleep.  But we do merit by our virtues.  Therefore virtues are not habits, but acts.

Obj. 4:  Further, Augustine says (De Moribus Eccl. xv) that “virtue is the order of love,” and (QQ. lxxxiii, qu. 30) that “the ordering which is called virtue consists in enjoying what we ought to enjoy, and using what we ought to use.”  Now order, or ordering, denominates either an action or a relation.  Therefore virtue is not a habit, but an action or a relation.