Nov. 10 is the Roman Catholic Church’s liturgical memorial of the
fifth-century Pope Saint Leo I, known as “St. Leo the Great,” whose
involvement in the fourth ecumenical council helped prevent the spread
of error on Christ's divine and human natures.
St. Leo intervened for the safety of the Church in the West as well, persuading Attila the Hun to turn back from Rome.
Eastern Catholics and Eastern Orthodox Christians also maintain a
devotion to the memory of Pope St. Leo the Great. Churches of the
Byzantine tradition celebrate his feast day on Feb. 18.
“As the nickname soon attributed to him by tradition suggests,” Pope
Benedict XVI said in a 2008 general audience on the saint, “he was truly
one of the greatest pontiffs to have honoured the Roman See and made a
very important contribution to strengthening its authority and
prestige.”
Leo’s origins are obscure and his date of birth unknown. His ancestors
are said to have come from Tuscany, though the future pope may have been
born in that region or in Rome itself. He became a deacon in Rome in
approximately 430, during the pontificate of Pope Celestine I.
During this time, central authority was beginning to decline in the
Western portion of the Roman Empire. At some point between 432 and 440,
during the reign of Pope St. Celestine’s successor Pope Sixtus III, the
Roman Emperor Valentinian III commissioned Leo to travel to the region
of Gaul and settle a dispute between military and civil officials.
Pope Sixtus III died in 440 and, like his predecessor Celestine, was
canonized as a saint. Leo, away on his diplomatic mission at the time of
the Pope’s death, was chosen to be the next Bishop of Rome. Reigning
for over two decades, he sought to preserve the unity of the Church in
its profession of faith, and to ensure the safety of his people against
frequent barbarian invasions.
Leo used his authority, in both doctrinal and disciplinary matters,
against a number of heresies troubling the Western church – including
Pelagianism (involving the denial of Original Sin) and Manichaeanism (a
gnostic system that saw matter as evil). In this same period, many
Eastern Christians had begun arguing about the relationship between
Jesus’ humanity and divinity.
As early as 445, Leo had intervened in this dispute in the East, which
threatened to split the churches of Alexandria and Constantinople. Its
eventual resolution was, in fact, rejected in some quarters – leading to
the present-day split between Eastern Orthodoxy and the so-called
“non-Chalcedonian churches” which accept only three ecumenical councils.
As the fifth-century Christological controversy continued, the Pope
urged the gathering of an ecumenical council to resolve the matter. At
the Council of Chalcedon in 451, the Pope’s teaching was received as
authoritative by the Eastern bishops, who proclaimed: “Peter has spoken
through the mouth of Leo.”
Leo’s teaching confirmed that Christ’s eternal divine personhood and
nature did not absorb or negate the human nature that he assumed in time
through the Incarnation. Instead, “the proper character of both natures
was maintained and came together in a single person.”
“So without leaving his Father's glory behind, the Son of God comes
down from his heavenly throne and enters the depths of our world,” the
Pope taught. “Whilst remaining pre-existent, he begins to exist in time.
The Lord of the universe veiled his measureless majesty and took on a
servant's form. The God who knew no suffering did not despise becoming a
suffering man, and, deathless as he is, to be subject to the laws of
death.”
In 452, one year after the Council of Chalcedon, Pope Leo led a
delegation which successfully negotiated with the barbarian king Attila
to prevent an invasion of Rome. When the Vandal leader Genseric occupied
Rome in 455, the Pope confronted him, unarmed, and obtained a guarantee
of safety for many of the city’s inhabitants and the churches to which
they had fled.
Pope St. Leo the Great died on Nov. 10, 461. He was proclaimed a Doctor
of the Church by Pope Benedict XIV in 1754. A large collection of his
writings and sermons survives, and can be read in translation today.