Chapter 18 — Part II: The Sacraments — The Holy Eucharist
Section 184. The Mass Profits Both The Living And The Dead — Pastors should next teach that such is the efficacy of this Sacrifice that its benefits extend not only to the celebrant and communicant, but to all the faithful, whether living with us on earth, or already numbered with those who are dead in the Lord, but whose sins have not yet been fully expiated. For, according to the most authentic Apostolic tradition, it is not less available when offered for them, than when offered for the sins of the living, their punishments, satisfactions, calamities and difficulties of every sort.