To the Bishops of Italy, on the Manichaeans

Leo to all the bishops set over the provinces of Italy, greeting.

We call you to share our anxiety, so that with the diligence of shepherds you may watch more carefully over the flocks entrusted to you, and no craft of the devil may be allowed. Otherwise that plague which, by the Lord’s revealing mercy, is being driven from our flocks through our care, may spread among your churches before you are warned and while you still do not know what is happening, and may find ways of burrowing secretly into your midst; and so what we are checking in the city may take hidden root among you and grow. Our search has discovered in the city a great many followers and teachers of the Manichaean impiety. Our watchfulness has exposed them, and our authority and censure have checked them. Those we could reform we have corrected and compelled to condemn Mani, with his preaching and teaching, by public confession in church and by the signature of their own hand; and so, by granting them room for repentance, we have lifted those who acknowledged their fault out of the pit of their wickedness. [a]

A good many, however, who had involved themselves so deeply that no remedy could help them, have been made subject to the laws, in accordance with the decrees of our Christian emperors; and, lest they pollute the holy flock by their contagion, they have been banished into perpetual exile by the public judges. And all the profane and disgraceful things found both in their writings and in their secret traditions we have disclosed and clearly proved before the eyes of the Christian lay people, so that the people might know what to shrink from and avoid. So it was that the man they called their bishop was himself tried by us, and betrayed the criminal beliefs he held in his secret religion, as the record of our proceedings can show you. We have sent you this record too, for your instruction; and after reading it you will be able to understand all that we have discovered.

And because we know that a good many of those who are implicated here too closely to clear themselves have escaped, we have sent this letter to you, beloved, by our acolyte, so that your holiness, dear brothers, may be informed of this and may see fit to act with diligence and caution, lest the men of the Manichaean error find an opportunity of harming your people and 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 destroy others and are themselves destroyed, and cut them off, with all the severity we can bring to bear, from contact with sound minds, lest this pestilence spread much wider. Therefore I exhort you, beloved, I beg and warn you, to use all the watchful diligence you ought and can in tracking them down, so that they find no chance of hiding anywhere. For as he who carries out what serves the health of the people committed to him will have a due recompense from God, so before the Lord’s judgment seat no one will be able to clear himself of a charge of carelessness who has not been willing to guard his people against those who spread an impious false belief. Dated the 30th of January, in the consulship of the illustrious Theodosius Augustus, for the eighteenth time, and Albinus (in the year 444). [d]