Reply Obj. 1: Every sacrament is something simple by reason of the Divine power, which operates therein: but the Divine power is so great that it can operate both through one and through many, and by reason of these many, parts may be assigned to a particular sacrament.
Reply Obj. 2: Parts are not assigned to penance as a virtue: because the human acts of which there are several in penance, are related to the habit of virtue, not as its parts, but as its effects. It follows, therefore, that parts are assigned to Penance as a sacrament, to which the human acts are related as matter: whereas in the other sacraments the matter does not consist of human acts, but of some one external thing, either simple, as water or oil, or compound, as chrism, and so parts are not assigned to the other sacraments.
Reply Obj. 3: Sins are the remote matter of Penance, inasmuch, to wit, as they are the matter or object of the human acts, which are the proper matter of Penance as a sacrament. _______________________
SECOND ARTICLE [III, Q. 90, Art. 2]
Whether Contrition, Confession, and Satisfaction Are Fittingly
Assigned As Parts of Penance?
Objection 1: It would seem that contrition, confession, and satisfaction are not fittingly assigned as parts of Penance. For contrition is in the heart, and so belongs to interior penance; while confession consists of words, and satisfaction in deeds; so that the two latter belong to interior penance. Now interior penance is not a sacrament, but only exterior penance which is perceptible by the senses. Therefore these three parts are not fittingly assigned to the sacrament of Penance.
Obj. 2: Further, grace is conferred in the sacraments of the New Law, as stated above (Q. 62, AA. 1, 3). But no grace is conferred in satisfaction. Therefore satisfaction is not part of a sacrament.
Obj. 3: Further, the fruit of a thing is not the same as its part.
But satisfaction is a fruit of penance, according to Luke 3:8: "Bring
forth . . . fruits worthy of penance." Therefore it is not a part of
Penance.
Obj. 4: Further, Penance is ordained against sin. But sin can be completed merely in the thought by consent, as stated in the Second Part (I-II, Q. 72, A. 7): therefore Penance can also. Therefore confession in word and satisfaction in deed should not be reckoned as parts of Penance.
On the contrary, It seems that yet more parts should be assigned to Penance. For not only is the body assigned as a part of man, as being the matter, but also the soul, which is his form. But the aforesaid three, being the acts of the penitent, stand as matter, while the priestly absolution stands as form. Therefore the priestly absolution should be assigned as a fourth part of Penance.