Leo, bishop, to Marcian, ever Augustus.
Chapter I: Thanksgiving for the Catholic Faith and the Peace of the Empire; Leo’s Confidence in Marcian’s Governance
How many things there are for which we must give thanks to our God — whose mercy it is that you, most glorious emperor, govern human affairs with such wise providence and excel in divine virtues — we have come to know fully from the arrival of Tatianus, the most illustrious prefect, your son, and the Constantinopolitan clerics who came to your piety. For the great material of ecclesiastical peace was made known to us from them, and we give thanks to the Lord that those who had been drawn away from the right path are being restored to the unity of the Catholic faith. For among Christian princes, the Spirit of God confirming concord, a twin trust in piety roborates both: because the invincible power of arms makes for the security of the faithful, and the sincere devotion of faith in the one confession, propitiating God through peace, shatters heretical falseness and barbarian hostilities alike. I presume, accordingly, that nothing impudent will arise from any quarter to trouble your serenity — since your spirit, rooted in the love of God, cannot be moved by anyone’s rash presumption.
Chapter II: It Is Sacrilege to Reopen Settled Questions; The Scriptures Must Be Interpreted as the Fathers Have Interpreted Them
But it is altogether too unjust that through the foolishness of a few we should be called back to the conjectures of opinions and the wars of carnal disputes — as if it were necessary to reopen the question of whether Eutyches thought impiously, or whether Dioscorus judged perversely — who in the condemnation of the most holy memory of Flavian both struck down simplicity and drove it to ruin, that many fell along with him into the same pit of condemnation. There are remedies for those who are converted, and pardon for those who repent; but those of this kind whose faith is wickedness, let them not be received unless they provide fitting satisfaction.
For it is impious that the divine Scriptures and the teachings of the holy Fathers be interpreted by anyone otherwise than the Holy Spirit, through whom they were written and delivered, has directed — for the disciples of truth ought not to follow the inventions of human error, but to seek the rule of faith in the writings of the prophets and apostles, in the expositions of the Catholic doctors, and in the definitions of the synods: none of which will be found to conflict, for all proceed from one and the same Spirit. Let whatever is contrary to these be avoided as deadly, and let the evangelical and apostolic doctrine, illuminated by the explanations of the holy Fathers, be held without any wavering.
Given on the ninth day before the Kalends of May, in the consulship of Adelfius, most illustrious man.
Footnotes
- ↩ Leo articulates here the relationship between imperial power and Catholic faith that runs through the whole patristic tradition: the emperor’s arms protect the faithful, and the Catholic confession propitiates God in a way that brings victory. This is not caesaropapism — the emperor serves the faith, not the other way around — but it is a genuine theology of Christian empire in which orthodox doctrine and political security are inseparable. The contrast with Theodosius’s court is implicit: Chrysaphius had inverted this order, using imperial power to impose a heretical settlement. Marcian has restored it.
- ↩ Leo is declaring the questions closed. Ephesus II’s validity, Eutyches’s heresy, Dioscorus’s corrupt judgment — these are not open questions awaiting fresh deliberation. They have been determined. Anyone seeking to reopen them is not conducting a legitimate theological inquiry; they are being foolish and impudent. The force of this declaration is jurisdictional as well as theological: Leo is not merely expressing a theological opinion about Eutyches and Dioscorus. He is stating that the matter is settled and that the Apostolic See’s judgment on it is not subject to revision through further dispute.
- ↩ Nefas est — “it is impious,” “it is sacrilege.” This is Leo’s strongest moral-religious condemnation, the same word he used in Letter IX for the suggestion that Alexandria could deviate from Rome’s practice (*nefas credere*). Here it is applied to interpreting Scripture otherwise than the holy Fathers — which is to say, otherwise than the tradition the Apostolic See holds and transmits. The declaration effectively closes the door on any further attempt to rehabilitate Eutychianism by appealing to alternative scriptural interpretations: the tradition is fixed, the Fathers have established it, and deviation from it is not theological creativity but sacrilege.
- ↩ April 23, 451 — ten days after the coordinated April 13 packet (Letters LXXVIII–LXXXI). The slightly later date suggests this letter was prompted by specific information brought by Tatianus the prefect and the Constantinopolitan clerics, who arrived in Rome and reported to Leo on the situation in Constantinople. Leo is responding to what they told him — including apparently some residual attempt by Eutychian sympathizers to reopen the doctrinal question — and closing it down firmly before his legates depart for Chalcedon.
Historical Commentary