Council of Trent: Session 14
Chapter 2
On the difference between the Sacrament of Penance and that of Baptism
For the rest, this sacrament is clearly seen to be different from baptism in many respects: for besides that it is very widely different indeed in matter and form, which constitute the essence of a sacrament, it is beyond doubt certain that the minister of baptism need not be a judge, seeing that the Church exercises judgment on no one who has not entered therein through the gate of baptism. For, what have I, saith the apostle, to do to judge them that are without? It is otherwise with those who are of the household of the faith, whom Christ our Lord has once, by the laver of baptism, made the members of His own body; for such, if they should afterwards have defiled themselves by any crime, He would no longer have them cleansed by a repetition of baptism—that being nowise lawful in the Catholic Church—but be placed as criminals before this tribunal; that, by the sentence of the priests, they might be freed, not once, but as often as, being penitent, they should, from their sins committed, flee thereunto. Furthermore, one is the fruit of baptism, and another that of penance. For, by baptism putting on Christ, we are made therein entirely a new creature, obtaining a full and entire remission of all sins: unto which newness and entireness, however, we are no ways able to arrive by the sacrament of Penance, without many tears and great labours on our parts, the divine justice demanding this; so that penance has justly been called by holy Fathers a laborious kind of baptism. And this sacrament of Penance is, for those who have fallen after baptism, necessary unto salvation; as baptism itself is for those who have not as yet been regenerated.
Chapter 3
On the parts, and on the fruit of this Sacrament.
The holy synod doth furthermore teach, that the form of the sacrament of penance, wherein its force principally consists, is placed in those words of the minister, I absolve thee, &c: to which words indeed certain prayers are, according to the custom of holy Church, laudably joined, which nevertheless by no means regard the essence of that form, neither are they necessary for the administration of the sacrament itself. But the acts of the penitent himself, to wit, contrition, confession and satisfaction, are as it were the matter of this sacrament. Which acts, inasmuch as they are, by God's institution, required in the penitent for the integrity of the sacrament, and for the full and perfect remission of sins, are for this reason called the parts of penance. But the thing signified indeed and the effect of this sacrament, as far as regards its force and efficacy, is reconciliation with God, which sometimes, in persons who are pious and who receive this sacrament with devotion, is wont to be followed by peace and serenity of conscience, with exceeding consolation of spirit. The holy Synod, whilst delivering these things touching the parts and the effect of this sacrament, condemns at the same time the opinions of those who contend, that, the terrors which agitate the conscience, and faith, are the parts of penance.