From the letter of Pope Leo to Flavian, bishop of Constantinople, about Eutyches

Surprised as we were at the late arrival of your charity's letter, we read it and examined the account of what the bishops had done. We now see what scandal against the integrity of the faith had reared its head among you. What had previously been kept secret now became clearly revealed to us. Eutyches, who was considered a man of honour because he had the title of priest, is shown to be very rash and extremely ignorant. What the prophet said can be applied to him: He did not want to understand and do good: he plotted evil in his bed. What can be worse than to have an irreligious mind and to pay no heed to those who are wiser and more learned? The people who fall into this folly are those in whom knowledge of the truth is blocked by a kind of dimness. They do not refer to

—the sayings of the prophets, nor to

—the letters of the apostles, nor even to

—the authoritative words of the gospels,

but to themselves. By not being pupils of the truth, they turn out to be masters of error. A man who has not the most elementary understanding even of the creed itself can have learnt nothing from the sacred texts of the New and Old Testaments. This old man has not yet taken to heart what is pronounced by every baptismal candidate the world over!

He had no idea how he ought to think about the incarnation of the Word of God; and he had no desire to acquire the light of understanding by working through the length and breadth of the holy scriptures. So at least he should have listened carefully and accepted the common and undivided creed by which the whole body of the faithful confess that they believe in

1. God the Father almighty and in

2. Jesus Christ his only Son, our Lord,

3. who was born of the holy Spirit and the virgin Mary.

These three statements wreck the tricks of nearly every heretic. When God is believed to be both almighty and Father, the Son is clearly proved to be co-eternal with him, in no way different from the Father, since he was born God from God, almighty from the Almighty, co-eternal from the Eternal, not later in time, not lower in power, not unlike in glory, not distinct in being. The same eternal, only-begotten of the eternal begetter was born of the holy Spirit and the virgin Mary. His birth in time in no way subtracts from or adds to that divine and eternal birth of his: but its whole purpose is to restore humanity, who had been deceived, so that it might defeat death and, by its power, destroy the devil who held the power of death. Overcoming the originator of sin and death would be beyond us, had not he whom sin could not defile, nor could death hold down, taken up our nature and made it his own. He was conceived from the holy Spirit inside the womb of the virgin mother. Her virginity was as untouched in giving him birth as it was in conceiving him.

From the Libellus of John of Constantinople to Hormisdas of Rome

The first condition of salvation is to keep the norm of the true faith and in no way to deviate from the established doctrine of the Fathers. For it is impossible that the words of our Lord Jesus Christ, who said, "Thou art Peter, and upon this rock I will build my Church," should not be verified. And their truth has been proved by the course of history, for in the Apostolic See the Catholic religion has always been kept unsullied. From this hope and faith we by no means desire to be separated and, following the doctrine of the Fathers, we declare anathema all heresies, and, especially, the heretic Nestorius, former bishop of Constantinople, who was condemned by the Council of Ephesus, by Blessed Celestine, bishop of Rome, and by the venerable Cyril, bishop of Alexandria. We likewise condemn and declare to be anathema Eutyches and Dioscoros of Alexandria, who were condemned in the holy Council of Chalcedon, which we follow and endorse. This Council followed the holy Council of Nicaea and preached the apostolic faith. And we condemn the assassin Timothy, surnamed Aelurus and also Peter of Alexandria, his disciple and follower in everything. We also declare anathema their helper and follower, Acacius of Constantinople, a bishop once condemned by the Apostolic See, and all those who remain in contact and company with them. Because this Acacius joined himself to their communion, he deserved to receive a judgment of condemnation similar to theirs. Furthermore, we condemn Peter of Antioch with all his followers together together with the followers of all those mentioned above.

Following, as we have said before, the Apostolic See in all things and proclaiming all its decisions, we endorse and approve all the letters which Pope St Leo wrote concerning the Christian religion. And so I hope I may deserve to be associated with you in the one communion which the Apostolic See proclaims, in which the whole, true, and perfect security of the Christian religion resides. I promise that from now on those who are separated from the communion of the Catholic Church, that is, who are not in agreement with the Apostolic See, will not have their names read during the sacred mysteries. But if I attempt even the least deviation from my profession, I admit that, according to my own declaration, I am an accomplice to those whom I have condemned.

The Emperors Gratian, Valentinian, and Theodosius to the people of the City of Constantinople

We desire that all peoples subject to Our benign Empire shall live under the same religion that the Divine Peter, the Apostle, gave to the Romans, and which the said religion declares was introduced by himself, and which it is well known that the Pontiff Damasus, and Peter, Bishop of Alexandria, a man of apostolic sanctity, embraced; that is to say, in accordance with the rules of apostolic discipline and the evangelical doctrine, we should believe that the Father, Son, and Holy Spirit constitute a single Deity, endowed with equal majesty, and united in the Holy Trinity.

Orate pro nobis!