To Eusebius, Archbishop of Thessalonica, on Peace and the Council of Chalcedon

Gregory to Eusebius, and so on. [a] If, most dear brother, we consider carefully how great the excellence of peace is, we will see how earnestly we ought to cultivate it. For indeed our Lord and Redeemer was pleased to leave it and give it to his disciples as a great gift, so that by it he might make those who were united to him in firm faith his companions in loving fellowship with himself. For it is written, “Blessed are the peacemakers, for they will be called the children of God.” Whoever, then, wants to be the Father’s heir, let him not refuse to be his child by keeping peace. For whoever gives way to discord surely cuts himself off from any share in so great a gift. Since, then, by the mercy of God the purity of your faith has been declared to us with catholic correctness, as was fitting, we are greatly surprised that you should allow those whom you know to believe well and think rightly to be needlessly shaken by the fault of certain persons, so that your fraternity’s reputation is clouded by the guilt of others. For how can a man escape the suspicion of error who puts up with those who are in error? Or what opinion of himself can he expect, if he does not see to it that what the fervor of faith requires to be cleansed is cleansed by open satisfaction? [b]

For indeed it is said that Luke, your presbyter, and Peter refuse to receive the Synod of Chalcedon, and that for this reason the hearts of your orthodox children are troubled and not a little offended. And since their zeal is not only to be praised but also to be wholeheartedly cherished, we urge your fraternity to take care, without hesitating, to look into the matter with all diligence and concern. If these men are found innocent of that perverse error, remove the stumbling block from the minds of your children by giving them satisfaction. And among all heresies anathematize especially Severus and Nestorius, so that cleansing may bring forth love among those in whom a dark suspicion about those heretics has, out of love for the faith, produced dissension; and so that one feeling of harmony may knit together for their good those whom a pure and single confession of catholic truth unites. Nor let the doubters be thought unworthy of satisfaction, since we are taught by the divine voice, “Do not despise one of these who are the least.” So whoever does not want him who instructs us to be despised, let him not reject the words of the instructor. For he too of whom our Redeemer testified that he was a chosen vessel for himself urges us to keep the unity of the Spirit in the bond of peace. So whoever does not refuse to be held by this bond of salvation, let him pursue the things that make for peace and give no room to the enemy, so that the enemy, who has been able to advance through the fierce dissension of brothers, may be trampled down all the more firmly once unity is established. [c]

If, however, as we do not expect, they should be found wounded by the dart of this error, the cure of the church’s exhortation must be applied to them, so that they may either remain among the Lord’s sheep if they are healed, or be cut off from the unity of the church’s body. In this way a great gain may come from a slight loss, and the removal of a part may set the whole body free. For it is the care of a provident shepherd, too, not to delay in casting out from the company of his healthy sheep a sick one that cannot be cured, lest it infect the others with the taint of its sickness, since he knows that he cannot keep the rest healthy except by putting this one out. Accordingly I warn you once more in brotherly love to investigate this matter with the utmost vigilance, and to carry out what we have written with the utmost care, lest by keeping company with others you make the right faith you hold seem doubtful. For whoever does not correct what should be cut away commits it himself. So you must take thought with great concern and great foresight in every way, so that the persons of those men may not be a stumbling block to others, nor common opinion harmful to you. Then a shepherd’s gains will come to your fraternity from the sheep entrusted to you, all the more as both sincere love and proven care have made you concerned to guard them.