Scholion. On the Virtue of Penance

The virtue of penance is a habit inclining man to the destruction of his own past sin, insofar as it is an offense against God (St. Thomas, part 3, question 85, article 2). Moreover:

The remote material object is every personal sin, even one remitted. The proximate material object is its acts, whether elicited or commanded. The chief elicited acts are detestation, sorrow, and the purpose of not sinning further; the commanded acts are all those acts of other virtues which the penitent performs from the motive of penance, or which he directs to expiating the offense.

The remote formal object is the violated divine right as to be repaired by satisfaction; but the proximate formal object is the special moral goodness shining forth in repairing, by satisfaction, the violated divine right.

Corollary I. Penance is a special virtue. "The species of habits," says Aquinas, "are distinguished according to the species of acts; and therefore, where a special praiseworthy act occurs, there it is necessary to posit a special habit of virtue. But it is manifest that in penance there is found a special aspect of a praiseworthy act, namely, to work for the destruction of past sin, insofar as it is an offense against God, which does not belong to the aspect of another virtue. Hence it is necessary to posit that penance is a special virtue" (part 3, question 85, article 2).

Corollary II. The special virtue of penance is a potential part of the cardinal virtue of justice; or, in other words, it participates in the nature of justice, yet is not perfect justice. The former is clear from the fact that justice regards those things which are owed to another (vol. I, n. 755). But penance regards the reparation of an offense owed to another, that is, to God. The latter follows from the fact that perfect justice renders what is owed according to equality (vol. I, n. 755). But man cannot render according to equality the reparation of the offense owed to God.