Leo, bishop, to Leo, Augustus.

Chapter I: No Reopening of the Faith After Chalcedon — To Do So Would Be to Overthrow What the Universal Church Has Received

I have received with reverence the letters of your clemency, full of the strength of faith and the light of truth — and I would wish, in that which your piety judges my presence necessary, to obey them even in this, so that a greater fruit might follow from the sight of your splendor. But I believe that what reason has shown to be the right choice will please you more. For since you are fortifying the peace of the universal Church with holy and spiritual zeal, nothing is more fitting for the defense of the faith than to adhere to those things which have been defined by the Holy Spirit without reproach. We would ourselves appear to be overturning what has been well established, and to be setting aside the authorities which the universal Church has embraced, yielding to the demand of heretical petition — and thus placing no limit on the collision of the Churches, but rather granting license to rebel and fanning the flames of conflict rather than suppressing them. Wherefore, since after those impieties of the Ephesine synod — by the crime of Dioscorus, the Catholic Faith was rejected and the perverse Eutychian doctrine received — nothing more useful for the preservation of the Christian Faith could be ordained than that the holy Council of Chalcedon should abolish the aforesaid crime: and that such heavenly care for doctrine should be maintained there, that nothing should remain in anyone’s opinion which was at variance with the prophetic, apostolic, or evangelical proclamations — with this moderation preserved, that pardon be denied to none who have been corrected, while those only who are stubborn and obstinate are rejected from the unity of the Church. What more probable or more religious course can your piety decree than that no one be permitted any further to assail those things which have been established not by human but by divine decrees — lest those truly prove worthy to lose so great a gift of God who have dared to call His truth into question?

Chapter II: Whoever Dares to Assault the Church’s Inexpugnable Strength Is Antichrist: What Nicaea and Chalcedon Each Defined

Since therefore the universal Church has been made a rock by the building up of that principal rock,1 and the most blessed Peter, first of the Apostles, heard the voice of the Lord saying: Thou art Peter, and upon this rock I will build my Church (Matt. 16:18) — who is there, save Antichrist or the devil himself, who would dare to assault its inexpugnable strength? Such a one, persevering in his malice with unchanged purpose, and employing vessels of wrath suited to his deceits, desires under the false name of diligence — while pretending to seek the truth — to sow nothing but lies. And rightly did his own uncontrolled fury and blind impiety prescribe what must be condemned and shunned; for by raging with diabolical impulse against the holy Alexandrian Church, it has made manifest what manner of men are those who wish the Chalcedonian synod to be reopened. In that Council it was utterly impossible to accept what the heretics falsely allege — that we were disposed against the holy Nicene synod: for the Nicene Fathers assembled against Arius affirmed not that the Lord’s flesh, but that the Divinity of the Son was homoousios, of one substance, with the Father; while in the Council of Chalcedon, against the impiety of Eutyches, it was defined that the Lord Jesus Christ took the truth of our body from the substance of the Virgin Mother.

Chapter III: Imperial Power Is Given Above All for the Defense of the Church: The Alexandrian Usurpers Must Be Expelled

Therefore, with a most Christian emperor — numbered with worthy honor among the preachers of Christ — speaking freely from the liberty of the Catholic Faith2 and securely in the fellowship of the Apostles and Prophets, I exhort you: that you steadfastly despise and repel those who have deprived themselves of the Christian name, and do not suffer impious parricides to deal in matters of faith under sacrilegious pretense — men who are known to wish to empty the faith of its content. For since the Lord has enriched your clemency with so great an illumination of His divine mystery, you must recognize without delay that royal power has been conferred upon you not only for the governing of the world, but above all for the defense of the Church3 — that by restraining wicked attempts you may defend what has been well established, and restore true peace to those things which have been thrown into disorder; driving out the usurpers of another’s right, and reforming the ancient seat of the Alexandrian Church in its traditional faith: so that, with God’s wrath mitigated by your corrections, He may not repay to a formerly devout city the sins that have been committed, but pardon them. Set before the eyes of your heart, most venerable emperor, that all the priests of the Lord throughout the whole world are making supplication to you for that faith in which the redemption of the whole world consists. Above all they who are followers of the Apostolic Faith press upon your piety, that you suffer not heretical men — justly condemned for their perversity — to continue in their usurpation: for whether you consider their impiety or attend to the deed of their perpetrated fury, they are not only unworthy of admission to the honor of the priesthood, but deserve to be cut off even from the Christian name itself. For, by your leave, most glorious emperor, they cast a certain shadow of contamination over the splendor of your serenity, since these sacrilegious parricides dare to petition for what even innocent men would not lawfully obtain.

Chapter IV: The Petitions of Catholics and Heretics Compared: The Catholics Petition Openly, the Heretics Conceal Themselves Under a Vague Collective Name

Prayers have been presented to your piety, copies of which you have attached to your own letters. In those which come from the Catholics who lament, there is a subscription: and because their cause is sound, the names of individuals and the dignity of each are set forth with confidence. But in those which heretical scheming has dared to present to an orthodox emperor — under the uncertain guise of an indeterminate collectivity — the precise name is withheld, lest not only the small number of persons but also their character be exposed. Their number, whose quality is already known, reckons it advantageous to remain hidden; and it is not without reason that those who have merited condemnation fear to profess who and whence they are. In the one petition, therefore, the supplication of Catholics is contained; in the other, the plots of heretics are laid bare. Here is lamented the overthrow of the Lord’s priests, of the entire Christian people, and of the monasteries; there the continuation of monstrous crimes is displayed — so that what it was not lawful to hear may at least be spread in writing.

Chapter V: All Christian Worship Has Been Extinguished at Alexandria: The Usurpers Deserve Not the Priesthood but Expulsion from the Christian Name

Is it not clear, then, to whom your piety should give aid and whom it should resist? Lest the Alexandrian Church — which was always the house of prayer — become now a den of thieves? It is manifest that by the most cruel and utterly insane savagery, the entire light of the heavenly sacraments has been extinguished there.4 The offering of sacrifice has been intercepted, the consecration of chrism has ceased, and the mysteries have withdrawn themselves from the parricide hands of the impious. Nor can there be any doubt of what must be determined concerning those who — after these unspeakable sacrileges, after the shedding of the blood of a most proven priest, and after the ashes of his burned body were scattered to the scorn of earth and sky — dare to claim for themselves the rights of a usurped dignity, and to summon the inviolable faith of Apostolic teaching before councils. Great indeed is the glory set before you: that to your crown your Lord may add also the crown of faith, and that you may triumph over the enemies of the Church — as it is glorious for you to have crushed the arms of hostile nations, how much more glorious to liberate the Alexandrian Church from a most insane tyrant, in whose oppression there is an injury to all Christians!

Chapter VI: Leo Promises Further Writings on the Faith, Rebukes Anatolius’s Excessive Leniency, and Commends Julian and Aetius to the Emperor

In order that my letter may present to your piety a conversation as it were of one present — whatever I was about to suggest concerning the common faith I have decided to set forth in the writings that follow. And lest the pages of this letter be extended to excessive length, I have included it in other letters which accord with the assertion of the Catholic Faith: so that, although what has been proclaimed from the Apostolic See would suffice of itself,5 these additional writings might nonetheless expose the snares of the heretics as well. A priestly and apostolic mind such as yours must be moved even by this evil to the exercise of just retribution: that certain clergy of the Church of Constantinople have been found who are in sympathy with the sensibility of the heretics, and within the very heart of the Catholic body are by their assertions giving aid to heretics. In driving out these persons — if my brother Anatolius, by showing excessive leniency, is found too slow — deign, for the sake of your own faith, to administer to that Church as well the medicine it requires: so that such persons may be expelled not only from the clerical order but also from residence in the city, lest the holy people of God be any further polluted by the contagion of perverse men. Moreover, I commend to your piety the servants of your devotion: Julian the bishop and Aetius the presbyter — at my petition I ask you to deign to hear their representations on behalf of the defense of the Catholic Faith, for they are of such character that they can be found in all things useful to your faith.

Given on the Kalends of December, in the consulship of Constantinus and Rufus, most distinguished men.