An indulgence is a remission before God of the temporal punishment for sin the guilt of which is already forgiven, which a properly disposed member of the Christian faithful obtains under certain and definite conditions with the help of the Church which, as the minister of redemption, dispenses and applies authoritatively the treasury of the satisfactions of Christ and the saints.
An indulgence is partial or plenary in as far as it frees from the temporal punishment due to sin either partly or totally.
The faithful can gain partial or plenary indulgences for themselves or apply them for the dead by way of suffrage.
—The Code of Canon Law1
For God’s only-begotten Son . . . has won a treasure for the militant Church . . . he has entrusted it to blessed Peter, the key-bearer of heaven, and to his successors who are Christ’s vicars on earth, so that they may distribute it to the faithful for their salvation. . . .
The “treasury of the Church” . . . is the infinite value, which can never be exhausted, which Christ’s merits have before God. . . . This treasury includes as well the prayers and good works of the Blessed Virgin Mary. They are truly immense, unfathomable, and even pristine in their value before God. In the treasury, too, are the prayers and good works of all the saints [who] . . . attained [by such good works] their own salvation and at the same time co-operated in saving their brothers. . . .
—Vatican II2
RIDES THE BEAST