Leo to Euxitheus, bishop of Thessalonica, and equally to the same.
Chapter I: Leo Writes by Virtue of His Solicitude for All the Churches, and Commends the Emperor’s Catholic Resolve
Having learned of what has been committed at Alexandria by the fury of the Eutychians — of which I do not doubt your brotherhood has been fully informed — by virtue of the duty of solicitude which I owe to all the Churches of God, I have directed these writings, by which I believed it necessary to admonish your charity: that you resist their wicked attempts with holy steadfastness, and that in none of us may the common faith be found either anxious or lukewarm. For with the favor of the Lord — who does not desert His Church in any tribulation — we have in the most devout emperor so religious and so Catholic a spirit that nothing different is to be believed of him than what we proved of the emperor of august memory, Marcian. Indeed, even while our own action was still pending, the most faithful emperor was so horrified by the parricidal crime that he granted no access whatsoever to the action of the heretics, who, after the enormity of the deed they had perpetrated, believed it possible that, with the definitions of the holy Chalcedonian synod dissolved, an episcopal council might be summoned for other proceedings.
Chapter II: Leo Commands Steadfast Adherence to Chalcedon and Directs That This Exhortation Reach All Bishops of Illyricum
Because this, dearest brother, is manifestly and abruptly hostile to the Christian faith, and is demanded with such wickedness for no other reason than that the preaching of the Gospel and the mystery of the Lord’s Incarnation might be subverted, I beseech your charity that you relax your minds in nothing from the definitions of the Chalcedonian synod, and suffer not those things which were composed by divine inspiration to be violated by any novelty. For I am certain that the most merciful emperor and the magnificent Patricius, together with all the assembly of the illustrious powers, will permit the heretics to gain nothing for the disturbance of the Church, if they shall see that pastoral minds waver in nothing. But in order that this exhortation may reach the notice of all our brothers and fellow bishops throughout Illyricum, let your diligence take care of this — for, as must often be said, the whole Christian religion is thrown into confusion if anything from what was decreed at Chalcedon should be overturned.
Given on the Kalends of September, in the consulship of Constantinus and Rufus.
Footnotes
- ↩ The header of this letter in the Patrologia Latina specifies that it was addressed equally to Juvenal of Jerusalem, Peter of Corinth, and Lucas of Dyrrachium. Juvenal was Patriarch of Jerusalem — the fifth of the five patriarchal sees recognized at Chalcedon — making him the most senior of the additional recipients. Peter of Corinth and Lucas of Dyrrachium were bishops within the Illyrian prefecture. Euxitheus of Thessalonica is named first because he was Leo’s vicar for Illyricum — the standing jurisdictional arrangement established through Letters V and VI, by which Rome governed the Illyrian episcopate through the bishop of Thessalonica as its designated instrument. The salutation naming Euxitheus alone in the body of the letter reflects his primary role; the others received identical copies to be received under his coordination.
- ↩ The formula pro ea sollicitudine quam omnibus Ecclesiis Dei debeo appears here word for word as in Letter CXLIX, written the same day to Basil of Antioch. Across the September 1 cluster Leo applies the identical theological ground — the universal solicitude he owes by office — whether writing to an emperor, a Patriarch of Antioch, a Patriarch of Jerusalem, or regional bishops of Illyricum. The formula does not vary by the dignity of the recipient. That invariance is the point: the ordinary and immediate jurisdiction of the Roman pontiff does not adjust its basis depending on the standing of the church being addressed. See the fuller treatment in the footnote to Letter CXLIX, Chapter I.
- ↩ The “parricidal crime” is the murder of Proterius, the orthodox bishop of Alexandria, during Holy Week of 457 — dragged from the baptistery by a mob of Eutychian partisans and killed. The Eutychians were followers of the archimandrite Eutyches, who had taught that Christ’s human nature was absorbed into his divine nature — a position condemned at the Council of Chalcedon in 451. With Proterius dead, the Eutychians installed their own candidate, Timothy Aelurus, in his place. The “other proceedings” they were demanding were a new general council that would revisit and overturn Chalcedon’s christological definitions — effectively reversing the settlement of 451 and rehabilitating the Eutychian position. Emperor Marcian’s death in January 457 had given them their opening; the murder of Proterius during the same period of political transition was the act that precipitated Leo’s coordinated response across this entire cluster of letters.
- ↩ The geographic specification “throughout Illyricum” (per Illyricum) is precise where Letter CXLIX’s parallel instruction to Basil of Antioch was general (“all our brothers and fellow bishops”). Leo is not simply encouraging the eastern episcopate broadly; he is governing a defined jurisdictional region through its designated instrument. The Illyrian vicariate — established in Letters V and VI, renewed under Leo as a standing structure — is here operating in its full practical form: Rome issues the directive; the vicar of Thessalonica distributes it; the entire Illyrian episcopate receives it. The vicariate is not an improvised arrangement for this crisis but a permanent channel of Roman governance, activated here as designed.
Historical Commentary