Council of Trent: Session XIV, Penance, Chapter II

CHAPTER II. 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.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).