The Church has always encouraged the faithful to pray for the souls of the faithful who have departed from this world. From the treasury of its merits, it grants its children indulgences, which are the most powerful way to assist the poor souls in purgatory. Through this gift of the Holy Catholic Church, one can obtain the remission of the temporal punishment due to sins already forgiven. Indulgences can be either applied to oneself or to any soul in purgatory.
An indulgence is the remission before God of the temporal punishment due to sins whose guilt has already been forgiven, a remission which one of the faithful, properly disposed and under certain definite conditions, can acquire through the Church which as minister of the redemption authoritatively dispenses and applies the treasure of the satisfactions of Christ and the saints.Handbook of Indulgences
One must be properly disposed and must follow the conditions that the Church lays out to gain an indulgence. The proper disposition and conditions are determined by the Church, which has been given by Christ the power to bind and loose, as the Minister of Our Lord’s redemption. The required disposition for a partial indulgence is having a contrite heart and being in a state of grace. Any work that the Church has sanctioned as indulgenced fulfills the condition. An indulgenced work can be as simple as an act of charity or a pious invocation before some task. Any indulgence, however seemingly small, can have great effect upon the sufferings of the poor souls in purgatory. This type of indulgence is known as a partial indulgence.
The other category of indulgence requires significantly more effort. This is called a plenary indulgence, in which the faithful soul fulfills the requirements to gain enough grace to erase all temporal punishment due to sin. A plenary indulgence can at most be gained once a day, except for those in danger of death. In order to fulfill the conditions, one must have gone to confession within a week before or after having offered the indulgence, received the Blessed Sacrament, prayed for the intentions of the Holy Father, and accomplished the work to which the indulgence is attached. In addition, attachment to all sin must be entirely absent.
The grace the Church bestows upon the recipient of an indulgence comes from the treasury of the merits of Christ, His saints, and the Blessed Mother. This treasury is inexhaustible, since an infinite amount of grace was gained solely by Our Lord’s passion.
The indulgenced works that we as the faithful accomplish tap into the Church’s Treasury of Grace and can be applied, not only to ourselves, but also to the souls in purgatory. The souls in purgatory are called ‘poor’ for a good reason. They are unable to do anything for themselves, and their only hope of a shortening of their purgation is the prayers and works of the faithful on earth. The most efficacious way for us to accomplish our Christian duty of helping the souls in purgatory is to take advantage of the great gift of indulgences that the Church offers us. Whenever we have the opportunity to offer an indulgence, we as the faithful on earth should do so, knowing that we are assisting the souls of those departed before us through the torments of their purgation.