Reply Obj. 1:  One act cannot belong to several powers equally, and in the same degree; but only from different points of view, and in various degrees.

Reply Obj. 2:  “To know” is a condition required for moral virtue, inasmuch as moral virtue works according to right reason.  But moral virtue is essentially in the appetite.

Reply Obj. 3:  Prudence is really subjected in reason:  but it presupposes as its principle the rectitude of the will, as we shall see further on (A. 3; Q. 57, A. 4). ________________________

THIRD ARTICLE [I-II, Q. 56, Art. 3]

Whether the Intellect Can Be the Subject of Virtue?

Objection 1:  It would seem that the intellect is not the subject of virtue.  For Augustine says (De Moribus Eccl. xv) that all virtue is love.  But the subject of love is not the intellect, but the appetitive power alone.  Therefore no virtue is in the intellect.

Obj. 2:  Further, virtue is referred to good, as is clear from what has been said above (Q. 55, A. 3).  Now good is not the object of the intellect, but of the appetitive power.  Therefore the subject of virtue is not the intellect, but the appetitive power.

Obj. 3:  Further, virtue is that “which makes its possessor good,” as the Philosopher says (Ethic. ii, 6).  But the habit which perfects the intellect does not make its possessor good:  since a man is not said to be a good man on account of his science or his art.  Therefore the intellect is not the subject of virtue.

On the contrary, The mind is chiefly called the intellect.  But the subject of virtue is the mind, as is clear from the definition, above given, of virtue (Q. 55, A. 4).  Therefore the intellect is the subject of virtue.

I answer that, As we have said above (Q. 55, A. 3), a virtue is a habit by which we work well.  Now a habit may be directed to a good act in two ways.  First, in so far as by the habit a man acquires an aptness to a good act; for instance, by the habit of grammar man has the aptness to speak correctly.  But grammar does not make a man always speak correctly:  for a grammarian may be guilty of a barbarism or make a solecism:  and the case is the same with other sciences and arts.  Secondly, a habit may confer not only aptness to act, but also the right use of that aptness:  for instance, justice not only gives man the prompt will to do just actions, but also makes him act justly.

And since good, and, in like manner, being, is said of a thing simply, in respect, not of what it is potentially, but of what it is actually:  therefore from having habits of the latter sort, man is said simply to do good, and to be good; for instance, because he is just, or temperate; and in like manner as regards other such virtues.  And since virtue is that “which makes its possessor good, and his work good likewise,” these latter habits are called virtuous simply:  because they make the work to be actually good, and