Pope Saint Leo I was the first of two Sovereign Pontiffs to be elevated to the noble and dogmatic structure of Doctor and be called "Great." The first, whom we feature today, was Leo the Great, who became the 45th in the line of Peter as Pope Leo I when he was chosen to succeed Pope Sixtus III on September 29, 440.
Born in Tuscany, Italy near the very end of the 4th Century, Leo came up through the ranks of the Deaconate and was in France attempting to reconcile the warring factions there when he was elected Pope. Though, like most pontiffs, he did not feel worthy, he nevertheless accepted the privileged and august duties of leading God's people through the middle of a most turbulent century.
Because of the alarming times and because of his position as head of the Church, the people looked to him for leadership and to save them from the plights that would afflict them, yet Leo, as a humble but effective deacon knew he couldn't do it by and of himself. He placed everything in God's hands and constantly sought the guidance of the Holy Ghost. Thus, in the hands of God, Leo became a powerful instrument to protect and honor the Church during the decay of the Roman Empire, the assaults of Arians, and the invasions of heathens.
Three years into his papacy Leo convened an assembly to rebuke and endorse Pope Innocent I's condemnation of Manicheanism as well as exposing Nestorianism, Priscillianism, and Arianism, and asserting the illegality of the Robber Council held in 449 without his approval. Just as the eleven Doctors of the Church who preceded him fought with every fiber of their being the heresies prevalent in their time, so also Leo was a champion 'hammer of heretics.'
In the aftermath of the fallout from the actions of the above council, Leo called the Fourth General or Oecumenical Council at Chalcedon in 451 where he staunchly defended the Incarnation, defining in his Tome the revealed teaching of faith that in Christ there are two distinct natures, the divine and the human, hypostatically united in one Person. He also condemned the heresy of Eutyches. But the Byzantine Court did not convey his words to the people and the heresy grew stronger among the Eastern monks and bishops. This made it necessary for Leo to convene the Fifth Oecumenical Council, this time at Constantinople where he condemned in no uncertain terms the Three Chapters or heresies running rampant. He thus became the only Pontiff to call two universal councils. He garnered the signatures of all the Bishops, proclaiming "Peter has spoken by Leo." He admonished his bishops to know their faith and to assure that their priests in each diocese were knowledgable in Dogma and Doctrine so that the people would not fall into the heresies that had assaulted the Church during the Third, Fourth and Fifth Centuries. What a novel idea lost on modernists today!
Leo not only assured unity within ecclesiastical ranks, but re-established harmony among the faithful. He is called "great" because of his energetic work in maintaining unity, his involvement in the liturgy, politics, preaching and writings, which have been cherished and passed on through the ages. He never compromised, never catered to worldly issues, but kept always before the people the Truths and Traditions of Holy Mother Church as the guiding light for all society. If ever we needed a Pope Leo it is in these times at the dawn of the third millennium.
To many historians his greatest accomplishment came in 451. The year before a barbaric horde known as the Huns had overrun the Empire, pillaging and plundering Gaul and moving rapidly from the north through Italy to the gates of Rome. Fearing no man, Leo chose to meet their ferocious leader Attila face to face at the gates. Many felt it was suicide and that Rome's fall was a fait accompli, but Leo knew God would protect him and so he bravely confronted the pagan king at the gates of Rome, pursuading Attila to abandon his plans to sack the city. To everyone's astonishment the man known as the "Scourge of God" rounded up his horde and turned away from Rome. It was another in the many encounters down through the centuries where, through the grace of God, a superior force is turned away, evidence David slaying Goliath, the victory at Lepanto, Saint Clare holding aloft the Blessed Sacrament in the monstrance to protect the city, and many more such cases where the power of God was manifested. Leo took very seriously his charge handed down from St. Peter to rule Christ's Church as Christ instructed. Leo knew it was not him who convinced Attila to forego his attempts on Rome, but the miraculous vision God allowed Attila to behold of Saints Peter and Paul standing behind Leo. The "Scourge of God" knew that any power this great was not to be messed with or he would be scourged by God, and so, totally overcome mentally by the vision he had seen, he retreated. It was the end of the threat so feared throughout Europe as the Hun king died two years later while Leo ruled another ten years, 21 in all, receiving his Heavenly reward on September 10, 461.
In 1754, St. Leo was declared a Doctor of the Church by Pope Benedict XIV, honoring this great Pope for his great writings and wisdom at a pivotal time in Church and world history. He had shown great courage and his skills at governing the Church and emphasizing spirituality while juggling the political footballs of his time. His actions strengthened the Vatican's position in the world while bringing the people to a closer understanding of what Jesus meant in His words to Peter in Matthew 16: 18-19, "Thou art Peter, and upon this rock I will build My Church, and the gates of hell shall not prevail against it. And I will give thee the keys of the Kingdom of Heaven; and whatever thou shalt bind on earth shall be bound in Heaven, and whatever thou shalt loose on earth shall be loosed in Heaven."
Leo's feast day in the universal Church was established as April 11 until the conciliar church ransacked and revised the liturgy, relegating his feast day to November 10th. It is still commemorated on April 11 by Traditional Catholics as it should be. His commemoration has always been celebrated in the eastern Church on February 18th.
Note: [editor's bold, brackets and italicized for emphasis] Some of the sources taken from: Les Petits Bollandistes: Vies des Saints, by Msgr. Paul Guérin (Bloud et Barral: Paris, 1882), Vol. 5; The Catholic Encyclopedia, edited by C. G. Herbermann with numerous collaborators (Appleton Company: New York, 1908).