Chapter 19 — Part II: The Sacraments — Penance
Section 106. Confession Should Be Entire — Pastors should teach, first of all, that care must be exercised that confession be complete and entire. All mortal sins must be revealed to the priest. Venial sins, which do not separate us from the grace of God, and into which we frequently fall, although they may be usefully confessed, as the experience of the pious proves, may be omitted without sin, and expiated by a variety of other means. Mortal sins, as we have already said, are all to be confessed, even though they be most secret, or be opposed only to the last two Commandments of the Decalogue. Such secret sins often inflict deeper wounds on the soul than those which are committed openly and publicly.