Leo to Flavian, bishop of Constantinople. He acknowledges the receipt of a letter and advises mercy if Eutyches will recant.
When our brethren had already started whom we despatched to you in the cause of the Faith, we received your letter, beloved, by our son Basil the deacon, in which you rightly said very little on the subject of our common anxiety, both because the accounts which had already arrived had given us full information on every thing, and because for purposes of private inquiry it was easy to converse with the aforesaid Basil, by whom now through the grace of God, in whom we trust, we exhort you, beloved, in reply, using the Apostle's words, and saying: "Be ye in nothing affrighted by the adversaries; which is for them a cause of perdition, but to you of salvation(2) ." For what is so calamitous as to wish to destroy all hope of man's salvation by denying the reality of Christ's Incarnation, and to contradict the Apostle who says distinctly: "great is the mystery of Godliness which was manifest in the flesh(3) ?" What so glorious as to fight for the Faith of the gospel against the enemies of Christ's nativity and cross? About whose most pure light and unconquered power we have already disclosed what was in our heart, in the letter which has been sent to you beloved(4) : lest anything might seem doubtful between us on those things which we have learnt, and teach in accordance with the catholic doctrine. But seeing that the testimonies to the Truth are so clear and strong that a man must be reckoned thoroughly blind and stubborn, who does not at once shake himself free from the mists of falsehood in the bright light of reason; we desire you to use the remedy of long-suffering in curing the madness of ignorance that through your fatherly admonitions they who though old in years are infants in mind, may learn to obey their elders. And if they give up the vain conceits of their ignorance and come to their senses, and if they condemn, all their errors and receive the one true Faith, do not deny them the mercifulness of a bishop's kind heart: although your judgment must remain, if their impiety which you have deservedly condemned persists in its depravity. Dated 23 July in the consulship of the illustrious Asturius and Protogenes (449).