Leo, bishop, to Proterius, Bishop of Alexandria.
Chapter I: Alexandria’s Obligation to Send Letters to the Apostolic See Grounded in the Petrine-Markan Derivation of Its Faith
Your letters — delivered by our brother and fellow bishop Nestorius with devoted care — have brought me great joy. It is fitting that the leader of the Church in Alexandria would send writings to the Apostolic See — demonstrating that the Egyptians have learned from the beginning, through the teaching of the blessed Apostle Peter passed on by his disciple Mark, the same faith that the Romans hold. For, as Scripture says, no other name is given to men under heaven whereby we must be saved (Acts 4:12) besides our Lord Jesus Christ. Yet since faith is not shared by all, and that cunning tempter delights in wounding human hearts with errors that oppose the truth of the Gospel, we must rely on the Holy Spirit’s profound guidance to ensure that Christian understanding remains untouched by the devil’s deceptions. Church leaders in particular must stay alert — steering the falsehoods disguised with a semblance of truth away from the souls of simple folk. The path to life is narrow and steep (Matt. 7:14). Traps lurk not only in how we live but also in the subtle distinctions of thought, where the meaning of sentences can be twisted by the smallest addition or alteration — turning a confession that leads to salvation into one that brings death. When the Apostle says, There must be heresies, that the approved may be manifest among you (1 Cor. 11:19), it serves the progress of the whole Church whenever the impieties of opposing views reveal themselves — preventing hidden harms from endangering others’ well-being: harms that cannot be healed and brought back to salvation.
Chapter II: The Tome Is No New Teaching; Proterius Must Instruct His People by Reading the Fathers’ Own Texts
My letter to Bishop Flavian of blessed memory — responding to Eutyches on the Incarnation of our Lord Jesus Christ — is not some new teaching. It deviates nowhere from the rule of faith upheld by our ancestors and yours alike. If Dioscorus had chosen to follow and imitate them, he would still be part of Christ’s body. He could have drawn instruction from the writings of blessed Athanasius, from the sermons of holy Theophilus and Cyril — rightly opposing the condemned dogma instead of aligning himself with Eutychian impiety. Therefore, dearest brother, in our shared concern for the faith, I urge you: since the enemies of Christ’s cross lie in wait for every word and syllable we utter, give them no opportunity — even the slightest — to falsely claim that we align with Nestorian error. Your diligence should encourage the people, the clergy, and the entire brotherhood toward growth in the faith — showing that you teach nothing novel but instill what the venerable Fathers proclaimed in harmonious preaching. This must be demonstrated not just through your words but by reading aloud the expositions of those who came before — so that the faithful may recognize that the doctrine being presented is the same one their ancestors received from their predecessors and passed on to posterity. For those less skilled in discernment, let them at least learn from the Fathers’ letters how ancient this evil is — the evil now condemned in Nestorius and Eutyches, who were ashamed to preach the Gospel of Christ according to the Lord’s own teaching.
Chapter III: The Ancient Standard of Faith, Discipline, and Church Privileges Is to Be Maintained; Alexandria’s Metropolitan Authority Over Its Provincial Bishops Confirmed
Uphold the ancient standard in both the rule of faith and the observance of discipline. Exercise the constancy of a wise leader, benefiting the Church of Alexandria. By vigilantly opposing the wicked ambitions of some, I have preserved the rights of ancestral privileges according to the canons — ensuring that metropolitans retain their dignity untarnished. My letters to the holy synod, the most Christian prince, or the bishop of Constantinople will show you this clearly. You will see that my special concern is to prevent any deviation from the rule of faith in the Lord’s churches, and to ensure that no one’s impropriety diminishes anyone’s privileges.
Given this, let your brotherhood maintain the custom of its predecessors. Keep your fellow provincial bishops — who are subject to the see of Alexandria by ancient constitution — under appropriate authority, so they do not rebel against ecclesiastical order. Let them convene with you at the appointed times or whenever a cause requires it, without delay. If anything beneficial to the Church’s interests needs discussion through common consultation, let the brotherhood — gathered as one — decide it unanimously. There is no reason for them to withdraw from this obedience, since your brotherhood is known to us for both faith and morals in such a way that We allow nothing to be diminished from the authority of your predecessors, nor for you to be contemned with impunity.
Dated the sixth day before the Ides of March, in the consulship of the most illustrious Aetius and Studius.
Footnotes
- ↩ Proterius had been installed at Alexandria after Dioscorus’s deposition at Chalcedon. He was one of the four Egyptians who had opposed Dioscorus at Chalcedon, and his election as bishop had involved the intervention of imperial authority. His position in the see was contested by the Eutychian party throughout his episcopate, and he would ultimately be murdered by Eutychian rioters in 457 during the crisis Leo addresses in Letters CXLVII onward. At this point (March 454) his authority is holding, and his letters of faith-profession to Leo have produced the warm response of Letter CXXIX.
- ↩ The phrase grounds Alexandria’s obligation to write to the Apostolic See in the same Petrine-Markan derivation argument Leo had used in Letter IX to Dioscorus: Alexandria’s faith derives from Peter through Mark, and the Roman Church abides in Peter’s institutions — therefore the two must accord, and it is fitting that Alexandria demonstrate this accord through its letters to Rome. The direction of the correspondence is significant: Proterius writes to Rome, demonstrating accord. The Apostolic See does not write to Alexandria requesting demonstration; Alexandria writes to the Apostolic See confirming it. The natural order of the relationship is described in a single sentence.
- ↩ Leo is telling Proterius directly that his post-Chalcedon correspondence — specifically the Canon 28 nullification — was directed in part at protecting Alexandria’s ancient privileges. The “wicked ambitions of some” is Anatolius’s Canon 28 campaign; the “rights of ancestral privileges according to the canons” are the Nicene provisions that gave Alexandria its established jurisdiction. Leo is informing the new bishop of Alexandria that the Apostolic See has already acted on his behalf and will continue to do so. This is pastoral protection exercised by the head on behalf of a member of the body.
- ↩ Leo confirms and directs Proterius’s metropolitan authority over the Egyptian provincial bishops. The phrase ex antiqua constitutione subjecti sunt — “subject to the see of Alexandria by ancient constitution” — is the same canonical ground Leo invokes against Canon 28: the ancient settlement established Alexandria’s jurisdiction over Egypt and Libya, and that jurisdiction is protected by the Nicene canons. Leo is telling Proterius both that his authority is secure and that he is expected to exercise it — provincial bishops who resist are not to be tolerated.
- ↩ March 10, 454. The PL editor’s note explains that Letters CXXIX, CXXX, and CXXXI are all dated the same day — with CXXIX to Proterius written first, CXXX to Marcian second, and CXXXI to Julian third, as established by internal evidence. This is another coordinated triple dispatch, structured on the same pattern as the March 21, 453 quadruple dispatch: addressing the same situation simultaneously through the ecclesiastical, imperial, and agential channels.
Historical Commentary