On the contrary, The precepts of the Law are about acts of virtue, because "a lawgiver intends to make the citizens virtuous" (Ethic. ii, 1). But there is a precept about penance in the Divine law, according to Matt. 4:17: "Do penance," etc. Therefore penance is a virtue.
I answer that, As stated above (Obj. 2; Q. 84, A. 10, ad 4), to repent is to deplore something one has done. Now it has been stated above (Q. 84, A. 9) that sorrow or sadness is twofold. First, it denotes a passion of the sensitive appetite, and in this sense penance is not a virtue, but a passion. Secondly, it denotes an act of the will, and in this way it implies choice, and if this be right, it must, of necessity, be an act of virtue. For it is stated in Ethic. ii, 6 that virtue is a habit of choosing according to right reason. Now it belongs to right reason than one should grieve for a proper object of grief as one ought to grieve, and for an end for which one ought to grieve. And this is observed in the penance of which we are speaking now; since the penitent assumes a moderated grief for his past sins, with the intention of removing them. Hence it is evident that the penance of which we are speaking now, is either a virtue or the act of a virtue.
Reply Obj. 1: As stated above (Q. 84, A. 1, ad 1; AA. 2, 3), in the sacrament of Penance, human acts take the place of matter, which is not the case in Baptism and Confirmation. Wherefore, since virtue is a principle of an act, penance is either a virtue or accompanies a virtue, rather than Baptism or Confirmation.
Reply Obj. 2: Penance, considered as a passion, is not a virtue, as stated above, and it is thus that it is accompanied by a bodily alteration. On the other hand, it is a virtue, according as it includes a right choice on the part of the will; which, however, applies to penance rather than to shame. Because shame regards the evil deed as present, whereas penance regards the evil deed as past. Now it is contrary to the perfection of virtue that one should have an evil deed actually present, of which one ought to be ashamed; whereas it is not contrary to the perfection of virtue that we should have previously committed evil deeds, of which it behooves us to repent, since a man from being wicked becomes virtuous.
Reply Obj. 3: It would indeed be foolish to grieve for what has already been done, with the intention of trying to make it not done. But the penitent does not intend this: for his sorrow is displeasure or disapproval with regard to the past deed, with the intention of removing its result, viz. the anger of God and the debt of punishment: and this is not foolish. _______________________
SECOND ARTICLE [III, Q. 85, Art. 2]
Whether Penance Is a Special Virtue?
Objection 1: It would seem that penance is not a special virtue. For it seems that to rejoice at the good one has done, and to grieve for the evil one has done are acts of the same nature. But joy for the good one has done is not a special virtue, but is a praiseworthy emotion proceeding from charity, as Augustine states (De Civ. Dei xiv, 7, 8, 9): wherefore the Apostle says (1 Cor. 13:6) that charity "rejoiceth not at iniquity, but rejoiceth with the truth." Therefore, in like manner, neither is penance, which is sorrow for past sins, a special virtue, but an emotion resulting from charity.
Obj. 2: Further, every special virtue has its special matter, because habits are distinguished by their acts, and acts by their objects. But penance has no special matter, because its matter is past sins in any matter whatever. Therefore penance is not a special virtue.
Obj. 3: Further, nothing is removed except by its contrary. But penance removes all sins. Therefore it is contrary to all sins, and consequently is not a special virtue.