The Life
Leo was born around 400 in Tuscany in northern Italy. He received the classical Christian education of late-antique Rome and entered the service of the Church of Rome as a young man. He was ordained acolyte and then deacon under Pope Celestine I and served as a senior diplomatic and theological adviser. He was a trusted adviser of Saint Cyril of Alexandria during the lead-up to the Third Ecumenical Council. Under Pope Sixtus III he was promoted to archdeacon. When Pope Sixtus III reposed in August 440, Leo was unanimously elected to succeed him. He served as Pope for the next twenty-one years. He composed the Tome to Flavian in 449, which was acclaimed by the Fourth Ecumenical Council at Chalcedon in 451 with the famous cry “Peter has spoken through Leo!” He met Attila the Hun outside Mantua in 452 and persuaded him to turn back from Rome. He met the Vandal Genseric at the gates of Rome in 455 and obtained mercy for the city’s inhabitants. He reposed November 10, 461.
Saint Leo entered the service of the Church of Rome as a young man. He was ordained acolyte and then deacon under Pope Celestine I. During Pope Celestine’s pontificate, he became a trusted theological adviser and was sent on important diplomatic missions to other churches. He occupied an important position with Saint Cyril of Alexandria during the lead-up to the Third Ecumenical Council at Ephesus in 431, helping to coordinate the Roman and Alexandrian responses to the Nestorian heresy. He continued to serve as a senior adviser under Pope Sixtus III (432–440), who promoted him to the position of archdeacon — effectively the second-most powerful figure in the Roman Church. The formation he received in those decades of senior service shaped the apostolic, theological, and diplomatic vision of his entire later pontificate.
When Pope Sixtus III reposed in August 440, Saint Leo was unanimously elected to succeed him as Bishop of Rome. He was at that moment on a diplomatic mission in Gaul, having been sent by the Western emperor Valentinian III to mediate a dispute between two Roman generals in southern Gaul. Word of his election reached him in Gaul. He returned to Rome and was consecrated Bishop of Rome on September 29, 440. He was about forty years old. He served as Pope for the next twenty-one years until his repose in 461. His pontificate fell in one of the most chaotic periods in the history of the Western Roman Empire. The Western Empire was in collapse. The Vandals had taken North Africa. The Goths and Burgundians were established in Gaul and Spain. The Huns under Attila were sweeping westward. The imperial authority in Italy was weak and increasingly ineffective.
The Christological controversy that had begun with Nestorius in 428 continued to develop after the Council of Ephesus. The Alexandrian monk Eutyches, in over-reaction to the Nestorian heresy, taught that after the union of the divine and human natures in Christ there was effectively only one nature — the divine nature having absorbed the human, like a drop of vinegar in the ocean. This heresy (called Eutychianism or Monophysitism) was condemned by Patriarch Saint Flavian of Constantinople at a local synod in 448. Eutyches appealed to Pope Saint Leo. Saint Leo studied the case and concluded that Eutyches’s teaching was indeed a heresy. He composed his famous Tome to Flavian (his Letter 28, addressed to Saint Flavian in June 449), which would become one of the foundational documents of the Eastern Christian Christological tradition.
Emperor Theodosius II convened a council at Ephesus in August 449 to settle the dispute. The council was dominated by supporters of Eutyches and presided over by Saint Cyril’s successor Dioscorus of Alexandria. Saint Leo’s legates attempted to read the Tome but were refused. The council deposed Saint Flavian, reinstated Eutyches, and declared the Eutychian Christology to be the Faith of the Church. Saint Leo immediately denounced the gathering as a “Robber Council” (Latrocinium). Theodosius II reposed in 450 and was succeeded by his sister Saint Pulcheria and her husband, the Emperor Marcian, who convened the Fourth Ecumenical Council at Chalcedon in 451. Some 630 bishops attended. The Council read Saint Leo’s Tome to Flavian; the Fathers received it with enthusiasm, crying out: “This is the faith of the Fathers! This is the faith of the Apostles! Peter has spoken through Leo!” The Council adopted the famous Chalcedonian Definition that has shaped the Eastern Christian Christological tradition for sixteen centuries.
In 452, the year after the Council of Chalcedon, the army of Attila the Hun, having ravaged northern Italy and threatening Rome itself, was met outside Mantua by a small unarmed delegation led personally by Pope Leo. The tradition records that Attila, after speaking with Saint Leo, turned his army around and withdrew from Italy. The Apostles Saint Peter and Saint Paul were said to have appeared with the Pope during the meeting, threatening Attila with destruction if he attacked Rome. The meeting became one of the most famous moments in the entire history of the medieval Western papacy. The image of the unarmed Pope standing before the barbarian conqueror and persuading him to spare Rome would shape the Western imagination of the apostolic vocation of the bishop for sixteen centuries.
Three years after Attila, in 455, when the Vandal king Genseric brought his army from North Africa to attack Rome, Saint Leo met him at the gates of the city, unarmed. He could not prevent the city’s sack. But he obtained guarantees of protection for the lives of its inhabitants, for the basilicas where they had taken refuge, and for the major churches of Rome. The Vandals plundered the city for two weeks but spared its people from massacre and burning. Many treasures were carried away, including the treasures of the imperial palaces and the relics of the Temple of Jerusalem that had been brought to Rome by Titus in 70 (and that Genseric carried to Carthage, from where they would later be recovered by Belisarius and brought to Constantinople). But the population of Rome survived. Saint Leo’s apostolic intervention had saved what could be saved.
Saint Leo understood his apostolic vocation as Bishop of Rome through the Lord’s words to Saint Peter at Caesarea Philippi. The Pope of Rome, in his apostolic self-understanding, was the heir of Saint Peter, the apostle to whom the Lord had committed the keys of the kingdom of heaven and the care of his sheep. The Council of Chalcedon’s acclamation of his Tome — “Peter has spoken through Leo!” — was the Eastern recognition that his theological work was a continuation of Saint Peter’s apostolic ministry. The apostolic vocation of every Bishop of Rome stands in this apostolic succession.
Saint Leo reposed in peace in Rome on November 10, 461. He was about sixty-one years old. He had been Pope of Rome for twenty-one years. He was buried near the tomb of the Apostle Saint Peter at the original Vatican Basilica; his relics rest to this day in Saint Peter’s Basilica in Rome. He is commemorated on November 10 in the Western tradition (the date of his repose) and on February 18 in the Eastern Orthodox tradition. The Roman Catholic Church declared him a Doctor of the Universal Church in 1754. The Eastern Orthodox Church has venerated him as one of the great fathers of the universal Church from the time of Chalcedon, calling him “Leo the Great” for his theological achievement and his apostolic defense of the Faith.
Leo gives the Christian Church a particular gift: the early Western dramatization that the apostolic vocation of the bishop combines theological precision with pastoral courage and unarmed witness before the powers of this world. He composed the Tome to Flavian that defended the apostolic Christology of the two natures of Christ. He stood unarmed before Attila the Hun and persuaded him to turn back from Rome. He stood unarmed before the Vandal Genseric and obtained mercy for the people of Rome. He preached the sermons that would shape the Western liturgy. He governed the Roman Church through the collapse of the Western Empire. We may not be Popes. But we will all face moments when we must combine theological clarity with pastoral courage in the historical circumstances the Lord has placed us in.