"But because, as it is written, in many things we all stumble (James 3.2), let the feeling of mercy be first aroused and the faults of others against us be forgotten; that we may not violate by any love of revenge that most holy compact, to which we bind ourselves in the Lord's prayer, and when we say forgive us our debts as we also forgive our debtors, let us not be hard in forgiving, because we must be possessed either with the desire for revenge, or with the leniency of gentleness, and for man, who is ever exposed to the dangers of temptations, it is more to be desired that his own faults should not need punishment than that he should get the faults of others punished. And what is more suitable to the Christian faith than that not only in the Church, but also in all men's homes, there should be forgiveness of sins? Let threats be laid aside; let bonds be loosed, for he who will not loose them will bind himself with them much more disastrously. For whatsoever one man resolves upon against another, he decrees against himself by his own terms. Whereas blessed are the merciful, for God shall have mercy on them: and He is just and kind in His judgments, allowing some to be in the power of others to this end, that under fair government may be preserved both the profitableness of discipline and the kindliness of clemency, and that no one should dare to refuse that pardon to another's shortcomings, which he wishes to receive for his own."
-St. Leo the Great, Homily 49, 'On Great Lent'