Prayers benefit the souls in Purgatory but cannot benefit the just in heaven or the damned in hell. The councils of Florence and of Trent, voicing the constant teaching and practise of the Church, have expressly declared that the souls in Purgatory are aided by the suffrages of the faithful. They are aided especially by the Mass, by indulgences, and by good works, such as prayers, alms, fasting, etc. These good works are applied by way of satisfaction, i.e., the satisfactory value of good works, which oonsists in the remission of punishment due to sin, is transferred to the poor souls. To apply the satisfactory merit to the dead the state of sanctifying grace is necessary for those works which produce their effects ex opere operantis, not, however, for those producing their effects ex opere operato, as the Mass, and prayers offered in the name of the Church. It is reasonable to hold that God always applies the satisfactory merits of good works, offered for the dead, to the poor souls; almost always to those souls for whom they are offered; not always, however, according to their full value, but in accordance with His justice, wisdom, and goodness.