Leo, bishop, to Theodoret, most beloved brother and bishop.
Chapter I: The Victory of the Faith at Chalcedon Demonstrates That What the First of All Sees Defined Was Received by the Universal Church
With our brothers and fellow bishops — who were sent by the see of blessed Peter to the holy council — now returned, I recognize that your charity, with heavenly aid, has triumphed together with us over Nestorian and Eutychian impiety. We glory in the Lord, singing with the prophet: Our help is in the name of the Lord, who made heaven and earth (Ps. 124:8). He permitted no loss among our brothers — confirming with universal agreement what Our ministry first defined, showing thereby that it came from Him: formed by the first of all sees and received by the judgment of the Christian world, so that head and members accord. Our joy grows as the enemy struck himself all the harder by raging against Christ’s ministers. Some — incited by the author of dissension — leapt to contradictions’ wars; yet by the all-good’s providence, greater good was reached through evil’s author.
Chapter II: Christ Won Through the Apostolic See; the Highest Summit Was Placed in the West
Rejoice, dearest brother, in the only Son of God — exult as victor. He won through us for Himself, whose flesh’s truth was denied; and for us, whom we served. This is the world’s second great festivity after the Lord’s Advent. The mystery of the divine Incarnation, obscured by the enemy’s slanders, was restored by the defeat of the robber. The sun of justice — its ray obstructed by the clouds of Nestorius and Eutyches in the East — shone with full purity from the West, where the Lord principally placed the highest summit in the apostles and in their teachers. Though He was never absent where He reserved noble confessors for Himself.
Chapter III: Dioscorus’s Hostility Against Leo Himself Was the Climax of His Crime
Through an impenitent heart — like a second Pharaoh — the ancient enemy tried to extinguish the seed of Abraham’s faith and the sons of promise, but, God’s mercy prevailing, he was able to harm only himself. God wondrously made those he had taken as allies in Israel’s slaughter not perish with their tyranny’s author but join His people. As the fount of true mercy deemed worthy, He made those whom we had overcome victors with us. The spirit of falsehood — humanity’s sole enemy — is triumphed over by all whom truth claims. The divine authority of the Redeemer’s words is clear — fitting the enemies of His faith, as if spoken of them: You are of your father the devil, and your father’s desires you will do. He was a murderer from the beginning and stood not in the truth, because truth is not in him. When he speaks a lie, he speaks of his own, for he is a liar and its father (John 8:44).
Chapter IV: Leo Urges Careful Balance in the Use of Theological Language on the Incarnation
It is no wonder that those who believe a lie about the truth of God’s nature and ours align with their father. Whatever seen, heard, or touched in the testimony of the Gospel concerning God’s only Son, they ascribe not to Him who was proven but to the substance of the coeternal and coessential Father — as if the nature of the Divinity were crucified, eternal Wisdom grew in age or wisdom, or God the Spirit were filled by the Spirit. This bitter madness reveals its own source, striving to harm all. Dioscorus — afflicting you by persecution and others by urging wicked agreement — wounded us, his members, with a special pain: daring a new, unheard, incredible injury against his own head. Had he repented after such evils, he would not have grieved us with his eternal damnation. What measure of crime did he spare — neither sparing the living nor the dead, dipping hands long stained in an innocent Catholic bishop’s blood in rejected truth and approved falsehood? As it is written: Whoever hates his brother is a murderer (1 John 3:15) — he, committed by hate, fulfilled it in deed — ignoring the Lord’s words: Learn from me, for I am meek and humble of heart, and you will find rest for your souls. For my yoke is sweet and my burden light (Matt. 11:29–30).
Chapter V: Theodoret’s Orthodoxy Is Confirmed; the Apostolic See’s Letter, Confirmed by the Universal Synod, Holds Divine Authority
Worthy of preaching diabolical error — this Egyptian devastator, like a cruel tyrant, imposed nefarious blasphemies on venerable brothers through seditious crowds and the bloody hands of soldiers. The Redeemer’s voice confirms one author of murder and falsehood (John 8:44), which he doubly fulfilled — dragging to ruin what the Son of God taught for salvation, ignoring: I speak what I have seen with My Father, and you do what you have seen with your father (John 8:38). By seeking Flavian’s present life, he lost the light of eternal life; by expelling you from your churches, he severed himself from Christians; by leading many to agreement in error, he wounded his soul multiply — guilty above, through, and for all.
Your brotherhood, strengthened by solid food, has no need of further support. Yet We fulfill the Apostle’s words: Besides those things without, my daily solicitude is the care of all the churches. Who is weak and I am not weak? Who is scandalized and I am not burned? (2 Cor. 11:28–29). When divine grace submerges or purges outsiders, We hold the Spirit-inspired rules of the faith of the Council of Chalcedon, balancing Our words with caution — not debating what is doubtful but asserting with the utmost authority what has been well defined. The letter of the Apostolic See, confirmed by the agreement of the universal synod, contains such testimonies of divine authority that none should doubt unless choosing to remain in error’s darkness. The synodal acts, the definition of the faith, the defense of my letter by your charity, the council’s address to the pious princes — all strengthened by the testimonies of the prior Fathers — will persuade any mind not yet damned with the devil, however unwise or obstinate.
Chapter VI: Theodoret Must Collaborate With the Apostolic See; Preaching Belongs Only to Bishops
Since remnants of the Eutychian and Nestorian error are known to remain, We exhort your collaboration with the Apostolic See. The victory of Christ to His Church, while granting greater confidence, does not end solicitude in this world — which is given not for sleep but for sweet labor. Let your vigilance’s reports hasten to inform the Apostolic See of the progress of the Lord’s doctrine — aiding the bishops of that region as needed.
Against illicit attempts in the council directed against the Nicene canons, We have written to our brother the bishop of Antioch — adding your report of certain monks’ wickedness — decreeing that none but the Lord’s bishops may preach, whether monk or layman who boasts of any knowledge. These letters We wish through Maximus to come to the knowledge of all, not adding copies here, trusting in his fulfillment. God keep you safe, dearest brother.
Dated the third day before the Ides of June, in the consulship of Opilio, most illustrious man.
Footnotes
- ↩ Theodoret (c. 393–458/466) was bishop of Cyrrhus — a city in northern Syria, modern Kurus in southern Turkey near the Syrian border. One of the most learned theologians of the fifth century, Theodoret had been a leading figure in the Antiochene theological tradition, had worked alongside Nestorius’s opponents while defending some of Nestorius’s persons, and had been unjustly condemned and deposed at the Latrocinium (449). He was rehabilitated at Chalcedon (451), where he was formally restored to his see — after publicly anathematizing Nestorius in the council’s presence. The PL apparatus confirms that this letter’s authenticity was attested at the Council of Chalcedon itself (Session 1, pag. 874). Leo’s letter to him is an acknowledgment of Theodoret’s rehabilitation and an enrollment of one of the East’s most distinguished theologians in the post-Chalcedon collaboration.
- ↩ The phrase a prima omnium sede formatum et totius Christiani orbis judicio receptum esse constaret: ut in hoc quoque capiti membra concordarent — “formed by the first of all sees and received by the judgment of the entire Christian world, so that in this too head and members accord” — is one of the most concentrated statements of the confirmatory authority in the entire corpus. The sequence is precise and deliberate: the first of all sees formed the definition; the Christian world received it; the head acted, the members agreed. This is not a conciliar deliberation that Leo subsequently endorsed; it is Leo’s definition that the council received. The head-and-members image matches what Chalcedon itself said in Letter XCVIII: Leo presided “as head over the members.” Here Leo himself uses the same image — and applies it to the doctrinal process: what the head defines, the members receive.
- ↩ The phrase ubi Dominus culmen summum in apostolis et doctoribus principaliter collocavit — “where the Lord principally placed the highest summit in the apostles and in their teachers” — applies Leo’s signature adverb principaliter (the same word used in Letter X to describe Peter’s governing position among the apostles) to the West — and specifically to Rome — as the seat of the highest apostolic summit. The light of the faith shines from the West because that is where the Lord principally placed the supreme apostolic authority. Compare Letter IX’s *apostolicum a Domino acceperit principatum* — Peter received the apostolic primacy from the Lord — and the present formulation: Rome is where that primacy was principally located, and it is from Rome that the light now disperses the Eastern darkness.
- ↩ Leo cites Paul’s sollicitudo omnium Ecclesiarum — “solicitude for all the churches” — as the scriptural ground of his own universal responsibility, making the apostolic authority of the Roman bishop’s sollicitudo explicit: it is not a Roman tradition or a canonical convention but the continuation of the apostolic charge Paul describes. Compare the sollicitudo formula throughout the Illyrian correspondence (Letters V, VI, X) and its application to the Eastern situation throughout the post-Chalcedon letters.
- ↩ The phrase apostolicae sedis epistola universalis synodi adsensu firmata, tanta divinae auctoritatis testimonia noverimus esse congesta — “the letter of the Apostolic See, confirmed by the agreement of the universal synod, contains such testimonies of divine authority” — names the relationship between Leo’s Tome and the Council of Chalcedon in precise terms. The Tome came first; the synod confirmed it. The divine authority of the testimonies is the Tome’s own; the synod’s agreement is the members’ accord with the head — not the source of the authority but its expression throughout the body. The reader should note the direction: it is the Apostolic See’s letter that holds the divine authority. The evidence of the whole sequence confirms this: Ephesus II assembled with equal or greater numbers and was declared a robber council because Leo withheld confirmation; Canon 28 was passed by five hundred bishops and nullified because Leo exercised his apostolic authority against it. The head defines; the members accord — or, where they do not accord, the head’s judgment prevails. Compare Chapter I’s “formed by the first of all sees and received by the judgment of the Christian world,” where Leo uses the same head-and-members image for the same reality.
- ↩ The directive to report to the Apostolic See and to aid the Eastern bishops “as needed” places Theodoret in the same position as Julian of Cos: a trusted Eastern agent through whom Leo’s solicitude is extended into the region. Theodoret’s distinction — as a theologian of the first rank, who had defended the Incarnation’s truth against both Nestorius’s error and Eutyches’s — makes his enrollment in the Apostolic See’s collaboration particularly significant. He is not merely an administrative agent; he is the theological witness to the tradition Leo has defended, now deployed to sustain it on the ground.
- ↩ June 11, 453 — the same date as Letter CXIX to Maximus of Antioch, making CXX and CXIX a coordinated pair: Leo writes to both the third and (through CXIX) the fourth apostolic see on the same day. CXX also explicitly coordinates with CXIX — Leo tells Theodoret that his report of the monks’ wickedness has been included in the letter to Maximus, and that Maximus will circulate both.
Historical Commentary