The manifold mercy of God so assists men when they fall, that not only by the grace of baptism but also by the remedy of penitence is the hope of eternal life revived, in order that they who have violated the gifts of the second birth, condemning themselves by their own judgment, may attain to remission of their crimes, the provisions of the Divine Goodness having so ordained that God's indulgence cannot be obtained without the supplications of priests. For the Mediator between God and men, the Man Christ Jesus, has transmitted this power to those that are set over the Church that they should both grant a course of penitence to those who confess, and, when they are cleansed by wholesome correction admit them through the door of reconciliation to communion in the sacraments. In which work assuredly the Saviour Himself unceasingly takes part and is never absent from those things, the carrying out of which He has committed to His ministers, saying: Lo, I am with you all the days even to the completion of the age (Matthew 28:20): so that whatever is accomplished through our service in due order and with satisfactory results we doubt not to have been vouchsafed through the Holy Spirit.
— St. Leo the Great, from Epistle 108. (11 June 452)