Leo to all the bishops set over the provinces of Italy greeting.
We call you to a share in our anxiety, that with the diligence of shepherds you may take more careful heed to your flocks entrusted to you that no craft of the devil's be permitted: lest that p ague, which by the revealing mercy of the Lord is driven off from our flocks through our care, should spread among your churches before you are forewarned, and are still ignorant of what is happening, and should find means of stealthily burrowing into your midst, and thus what we are checking in the City should take hidden root among you and grow up. Our search has discovered in the City a great many followers and teachers of the Manichaean impiety, our watchfulness has proclaimed them, and our authority and censure has checked them: those whom we could reform we have corrected and driven to condemn Manichaeus with his preachings and teachings by public confession in church, and by the subscription of their own hand, and thus we have lifted those who have acknowledged their fault from the pit of their iniquity by granting them room for repentance(1) . A good many, however, who had so deeply involved themselves that no remedy could assist them, have been subjected to the laws in accordance with the constitutions of our Christian princes, and lest they should pollute the holy flock by their contagion; have been banished into perpetual exile by public judges. And all the profaneand disgraceful things which are found as well in their writings as in their secret traditions, we have disclosed and clearly proved to the eyes of the Christian laity(2) that the people might know what to shrink from or avoid: so that he that was called their bishop was himself tried by us, and betrayed the criminal views which he held in his mystic religion, as the record of our proceedings can show you. For this, too, we have sent you for instruction: and after reading them you will be in a position to understand all the discoveries we have made.
And because we know that a good many of those who are involved here in too close an accusation for them to clear themselves have escaped, we have sent this letter to you, beloved, by our acolyth: that your holiness, dear brothers, may be informed of this, and see fit to act with diligence and caution, lest the men of the Manichaean error be able to find opportunity of hurting your people and of teaching their impious doctrines. For we cannot otherwise rule those entrusted to us unless we pursue with the zeal of faith in the Lord those who are destroyers and destroyed: and with what severity we can bring to bear, cut them off from intercourse with sound minds, lest this pestilence spread much wider. Wherefore I exhort you, beloved, I beseech and warn you to use such watchful diligence as you ought and can employ in tracking them out, lest they find opportunity of concealment anywhere. For as he will have a due recompense of reward from God, who carries out what conduces to the health of the people committed to him; so before the Lord's judgment-seat no one will be able to excuse himself from a charge of carelessness who has not been willing to guard his people against the propagators of an impious misbelief. Dated 30 January, in the consulship of the illustrious Theodosius Augustus (18th time) and Albinus (444).