And be it known to your holiness that Cyril and Memnon have not been satisfied with corrupting the orthodox Faith, but have trampled all the canons underfoot. For they have received into communion men excommunicated in various provinces and dioceses. Others lying under charges of heresy, and of the same mind as Celestius and Pelagius, (for they are Euchitæ, or Enthusiasts) and therefore excommunicated by their diocesans and metropolitans, they have, in defiance of all ecclesiastical discipline received into communion, so swelling their following from all possible quarters, and showing their eagerness to enforce their teaching less by piety than by violence. For when they had been stripped bare of piety they devised, in their extremity, another sort of force—walls of flesh, with the idea that by their showers of bribery they might vanquish the faith of the Fathers. But so long as your holiness puts forth your strength, and you continue to fight, as you are wont, in defence of true religion, none of these devices will be of the least avail. We exhort you therefore, most holy sir, to beware of the communion of the unscrupulous introducers of this heresy; and to make known to all, both far and near, that these are the points for which the thrice blessed Damasus deposed the heretics Apollinarius, Vitalius, and Timotheus; and that the Epistle in which the writer has concealed his heresy and coloured it with a coating of truth, must not in simplicity be received. For in the Chapters he has boldly laid bare his impiety, and dared to anathematize all who disagree with him, while in the letter he has vilely endeavoured to harm the simpler readers.
Your holiness must therefore beware of neglecting this matter, lest when, too late, you see this heresy confirmed, you grieve in vain, and suffer affliction at being no longer able to defend the cause of truth.
We have also sent you a copy of the memorial which we have given to the most pious and Christ-loving emperor, containing the faith of the holy Fathers at Nicæa. wherein we have rejected the newly-invented heresies of Cyril, and adjudged them to be opposed to the orthodox faith.
Since in accordance with the orders of the very pious emperor only eight of us travelled to Constantinople, we have subjoined the copy of the order given us by the holy synod, that you may be acquainted with the provinces contained in it. Your holiness will learn them from the signatures of the metropolitans. We salute the brotherhood which is with you.
Source: Letters (New Advent)