Leo I

Life events

1. Born

   Leo was born c. 391 in Tuscany, according to the Liber Pontificalis, which names his father as Quintianus or Quintilianus. He was a Roman aristocrat by background.

2. Ordained — 431

   By 431 Leo was serving as a deacon in Rome, prominent enough that John Cassian dedicated to him a treatise against Nestorius written at Leo's own suggestion. Around this time Cyril of Alexandria addressed Rome regarding a jurisdictional dispute with Juvenal of Jerusalem.

3. Consecrated — 440

   While in Gaul settling a dispute between the military commander Aëtius and the magistrate Albinus at Emperor Valentinian III's direction, Leo learned that Pope Sixtus III had died. On 29 September 440 he was unanimously elected Bishop of Rome.

4. Wrote — 449

   At the Second Council of Ephesus (449), Leo's representatives delivered the Tome of Leo — a letter to Archbishop Flavian of Constantinople setting out Western Christology. The council refused to read it and deposed Flavian; the letter was later presented at the Council of Chalcedon (451) as a resolution to the Christological controversy.

5. Council — 451

   The Council of Chalcedon (451), the fourth ecumenical council, accepted Leo's Tome and defined Christ's person as the hypostatic union of two natures, divine and human, in one person without confusion or division. The assembled bishops declared, "Peter has spoken thus through Leo." Leo declined to confirm the council's disciplinary canon elevating Constantinople.

6. Other — 452

   In 452, after Attila the Hun invaded Italy and sacked Aquileia, Emperor Valentinian III sent three envoys — including Leo — to negotiate near the south shore of Lake Garda. Attila withdrew from Italy following the embassy; contemporary sources such as Prosper of Aquitaine credit Leo's personal authority, while Priscus and John B. Bury argue that plague, food shortages, and troops arriving from the east were decisive factors.

7. Other — 455

   When the Vandal king Genseric sacked Rome in 455, Leo and his clergy went out to meet the invaders. Although the city was plundered, Leo's intervention prevented Rome from being burned and secured the safety of the Basilicas of St. Peter, St. Paul, and St. John.

8. Died — 461

   Leo died on 10 November 461 and was buried, as he wished, within the portico of Old St. Peter's Basilica — the first pope to be interred inside St. Peter's. In 688 Pope Sergius I moved his remains to the south transept of the basilica.

Relationships

Documented claims

• Pope Benedict XIV declared Leo I a Doctor of the Church in 1754. Only one other pope, Gregory I, also holds this title. (certain)
• Leo described himself as the unworthy heir and vicarius (deputy) of the Apostle Peter, grounding the Roman episcopal office in the special relationship between Christ and Peter — among the earliest systematic articulations of papal primacy by succession. (certain)
• In his Christmas Day sermon Leo articulated a doctrine of universal Christian dignity: "Christian, acknowledge thy dignity" — asserting that all baptized Christians, saints and sinners alike, share in the divine nature through the Incarnation. (certain)
• The Oriental Orthodox Church, at the Third Council of Ephesus following Chalcedon, condemned the Tome of Leo as Nestorian in tendency, holding that it contradicted Cyril of Alexandria's formula of "one nature of the Word of God incarnate." The Coptic Orthodox Church remains Miaphysite and does not accept Chalcedon. (certain)
• Nearly 100 sermons and 150 letters of Leo I survive, making him one of the best-documented popes of late antiquity. His writings range from Christological and Mariological theology to letters disciplining bishops across Gaul, Africa, Spain, and Illyria. (certain)