Saint Leo the Great (c. 390-400 – 461)

Only two popes bear this title

In the entire list of popes, only two have received from tradition the surname Magnus, “the Great”: Leo I (440-461) and Gregory I (590-604)^[4]. A few authors sometimes add Nicholas I, but the usage never caught on. The title is not a decree: it is a judgment of Christian memory, which recognized in Leo a man whose action and doctrine went beyond the ordinary measure of a pontificate.

What is striking is that Leo's greatness is not first that of a conqueror or an empire-builder — he lived, on the contrary, through the collapse of the Western Roman Empire — but that of a witness to the truth. Benedict XVI summed up his physiognomy in a formula: a pontificate “devoted to the service of the truth in charity, through an assiduous exercise of the word”^[5].

Saint, Father and Doctor of the Church

Leo combines the three great titles the Church reserves for her masters: he is a saint (venerated from his death), a Father of the Church (an ancient author whose teaching carries authority) and a Doctor of the Church (proclaimed as such by Benedict XIV in 1754)^[6]. He belongs to the great generation of Latin Fathers that immediately follows Ambrose, Jerome and Augustine: he gathers their doctrinal heritage and carries it to the summit of the Roman See.

The “Doctor of the Incarnation”

Tradition has given him a surname that expresses his distinctive contribution: “the Doctor of the Incarnation”. It is he who fixed, in language of perfect precision, the Church's faith in Christ true God and true man, “one person in two natures”. For Leo, this doctrine is not a theologian's abstraction: it is the very heart of salvation, which is why it returns constantly in his Christmas and Easter sermons (see below).

Tuscan origins

Information about Leo's youth is scarce. The Liber Pontificalis calls him “of Tuscan nationality” (natione Tuscus), son of a certain Quintianus^[7]. The date of his birth is not known with certainty: it is placed between 390 and 400. Roman in culture and heart, he was formed in the clergy of the City at a time when the Western Empire, undermined by invasions, was sliding toward ruin.

The deacon whom the whole Church listened to

Even before becoming pope, Leo was a Roman archdeacon whose reputation had crossed the Alps. Saint Cyril of Alexandria wrote to him; Bishop Augustine and his disciple Prosper of Aquitaine knew him; he was even entrusted, in 440, with a diplomatic mission to Gaul to reconcile General Aetius and Prefect Albinus. It was during this mission that he learned of his election to the See of Peter^[8][9].

A pastor in spite of himself, faithful to the end

Elected during his mission in Gaul, Leo was consecrated Bishop of Rome on 29 September 440 and would govern the Church for twenty-one years, one of the longest pontificates of antiquity. His holiness is not measured by length but by constancy: through heresies, invasions, famines and fear, he never ceased to preach, write, judge and console. The details of this government belong to the article Pope Saint Leo the Great; what concerns us here is the soul of this man as it shines through his sermons.

Nearly a hundred sermons in limpid Latin

From Leo we have an exceptional treasure: about ninety-six authentic sermons and one hundred and forty-three letters^[10]. Benedict XVI stresses the quality of this prose: “we still have almost a hundred of them in splendid and clear Latin”^[11]. They are, for the most part, brief homilies delivered on the great feasts of the liturgical year — Christmas, Epiphany, Lent, Passion, Easter, Ascension, Pentecost, the feast of Saint Peter — before the people of Rome gathered together.

This body of sermons is a rarity for the period: very few Latin Fathers have left us such a coherent homiletic corpus, issuing directly from a bishop's pulpit. It is in these texts, more than in official acts, that Leo's concrete holiness can be grasped: a man who takes the floor not to shine, but to lead his faithful into the mystery.

The preacher of the great feasts

Leo is above all the preacher of the liturgical year. For him, each feast is not the remembrance of a past event but its reactualization: the mystery celebrated acts here and now upon the believer's soul. This is one of his deepest intuitions, which he expresses in a formula that has become classic on the paschal mystery:

“What was visible in our Redeemer has passed into the sacraments.” — Saint Leo the Great, Sermon 74 on the Ascension, II^[12]

In other words: what the Apostles saw with their eyes in Christ — his flesh, his deeds, his Passion — continues to act, invisible but real, in the sacraments of the Church. The liturgy is not a theatre of remembrance; it is the place where salvation is still communicated.

The master of almsgiving and fasting

The pastor Leo never separates doctrine from concrete charity. His sermons on fasting — especially those of the Ember Days and Lent — inseparably link penance and almsgiving: to fast without giving to the poor would be, for Leo, an empty devotion.

Leo reminds the Christian people that their election — “a chosen race, a royal priesthood, a holy nation” (1 Pt 2:9) — is not a title for pride but a call to service: the greatness received at baptism must be translated into concrete mercy^[13].

This insistence on mercy toward the poor as the necessary fruit of fasting is one of the most constant features of his pastoral spirituality.

It is here that the saint reveals himself most: not in polemic, but in the way he teaches the Christian soul who it is and what it must live.

“Christian, acknowledge your dignity!”

The summit of Leonine spirituality is held in a single sentence, spoken in his first Christmas sermon:

“Christian, acknowledge your dignity! Having become a partaker of the Divine nature, refuse to return to the old baseness by degenerate conduct. Remember the Head and the Body of which you are a member. Recall that, rescued from the power of darkness, you have been transferred into the light and the Kingdom of God.” — Saint Leo the Great, Sermon 21 on the Nativity of the Lord, III^[14]

All of Leo is there. Christian morality is not first a list of prohibitions: it flows from a dignity received. Because the Son of God became man, baptized man has become a “partaker of the Divine nature” (2 Pt 1:4); sin is therefore not only a fault, it is a betrayal of oneself, a return to a baseness from which Christ had rescued us. This formula, “Agnosce, o Christiane, dignitatem tuam”, has nourished fifteen centuries of spirituality and still figures today in the Catechism of the Catholic Church^[15].

Christmas: God becomes man to raise man up

For Leo, the mystery of Christmas is the centre of everything. If God became man, it is “to restore to man his lost dignity”^[16]. The Incarnation is not an episode: it is the admirable exchange (admirabile commercium) by which God takes what is ours to give us what is his.

“Our Saviour, dearly-beloved, was born today: let us be glad. For there is no proper place for sadness, when we keep the birthday of the Life.” — Saint Leo the Great, Sermon 21 on the Nativity, I^[17]

It is also at Christmas that Leo expounds, in a few lines of perfect density, the faith that will be that of Chalcedon: Christ is “true God and true man”, two natures united without confusion in a single person. His Christmas joy and his dogmatic rigour are one: he sings the Incarnation because it saves.

The mystery passed into the sacraments

As we have seen, Leo teaches that the glorified Christ continues to act in the rites of the Church. This intuition makes him one of the great doctors of sacramental and liturgical life. The Christian who takes part in the liturgy does not attend a commemoration: he is made contemporary with the mystery of salvation. That is why Leo insists so much on the dignity with which the sacraments must be celebrated and received, and on the need to unite outward worship with the conversion of the heart.

The Cross and the Passion

Leo's sermons on the Passion rank among the finest of antiquity. In them he contemplates the Cross not as a defeat but as the throne from which Christ reigns and draws all things to himself:

For Leo, the Cross of Christ is the source of all blessings and the cause of all graces: through it, the weakness of believers is turned into strength, shame into glory, death into life^[18].

Here again, the doctrine of the two natures serves spirituality: it is because the one who suffers is true man that he can die, and because he is true God that his death saves the world.

Peter and Paul, Roman roots

Leo has a particular veneration for the apostles Peter and Paul, founders of the Church of Rome. His Sermon 82, delivered for their feast, is a masterpiece: in them he sees the new founders who made Rome — once mistress of nations by arms — mistress of the world by faith.

“These men, O Rome, have raised thee to such glory that, made a holy nation, a chosen people, a priestly and royal city, thou presidest over the world more widely by divine religion than by earthly domination.” — Saint Leo the Great, Sermon 82 on the feast of the apostles Peter and Paul, I^[19]

For Leo, his own authority as pope is nothing other than that of Peter living on in his successor: “to one apostle is entrusted what is communicated to all the apostles”^[20]. This awareness is not personal pride — Leo knows himself to be the “unworthy heir” of Peter — but service of the unity of the whole Church.

The shepherd who stands before the wolf

Leo's holiness also showed itself in a courage that has remained legendary. In 452, as Attila and his Huns threatened Rome, it was the bishop, not the emperor, who went out to meet him and turn him away from the city; in 455, facing the Vandal Genseric, Leo at least obtained that Rome, delivered over to pillage, be spared massacre and burning^[21]. These episodes — detailed in the article Pope Saint Leo the Great — say something about the saint: a shepherd who does not flee before danger, but stands between the flock and death.

The servant of truth in charity

Leo's whole life fulfils the motto Benedict XVI applies to him: service of truth in charity^[22]. Truth, for he never yielded an inch on faith in Christ true God and true man, against Nestorianism, which divides Christ, and Monophysitism, which confounds him. Charity, for this doctrinal firmness was at the service of the salvation of souls and the peace of the Church, never of his own glory. It is this unity of truth and love that makes him a saint, and not merely a skilful statesman.

Death on 10 November 461

After twenty-one years as pope, Leo died in Rome on 10 November 461^[23][24]. He left a Roman Church strengthened in faith and in awareness of her mission amid a collapsing world. His death was at once surrounded by the veneration of a saint.

The tomb at Saint Peter's and the relics

Leo was first buried in the portico (vestibule) of Saint Peter's Basilica, in the Vatican^[25]. In 688, Pope Sergius I had his remains transferred inside the basilica itself and raised an altar above his tomb^[26]: this was the consecration of his cult. Leo thus rests beside the apostle Peter, whose servant he had always wished to be; his relics are today venerated in the Vatican basilica.

The liturgical feast

The cult of Saint Leo is ancient and universal, but its date has varied:

The move of the feast to 10 November, after the liturgical reform of 1969, brought Leo's memory closer to his dies natalis — the day of his birth into Heaven.

The proclamation by Benedict XIV

For thirteen centuries, Leo was venerated as a saint and recognized as a Father of the Church, but without the formal title of Doctor. It was Pope Benedict XIV who, in 1754, raised him to the “dignity of Doctor of the Church”^[39][40]. Leo thus became, by his era, the earliest of the popes recognized as Doctors of the Church, by reason of the depth and clarity of his teaching on the Incarnation and Redemption.

“In 1754, Leo the Great was proclaimed Doctor of the Church by Benedict XIV.” — Benedict XVI, General Audience of 5 March 2008^[41]

What the Church recognizes in him

In making Leo a Doctor, the Church does not reward political skill: she solemnly recognizes a doctrine. Leo gave the Christian faith in Christ an expression so exact that it became, at Chalcedon, the rule of orthodoxy for all East and West. His teaching on the dignity of the Christian, on the liturgy as the actualization of the mystery, on the unity of truth and charity, continues to nourish the spirituality of the Church. He takes his place among the Doctors of the Church, alongside the great Latin Fathers whose heir he was.

Saint Leo speaks to our time. He too lived in a collapsing world — the Western Roman Empire was dying before his eyes — and he answered that anguish not with flight, but with a trust rooted in Christ and with patient work of truth and charity. He teaches the anxious Christian that his dignity does not depend on the solidity of empires, but on the grace received at baptism.

He also reminds us that doctrine and spiritual life are not opposed: it is because he firmly believed in Christ true God and true man that Leo could say to each person “acknowledge your dignity”. Far from a cold jurist of dogma, he is a shepherd who wants to lead his faithful into the joy of the Incarnation. For this the Church venerates him as saint, Father and Doctor; for this one can still place oneself in his school.

As he says in his anniversary sermon, although the universal Church is made up of members of various degrees, she grows entirely in her head, who is Christ^[42].

• Pope Saint Leo the Great (440-461) — the companion article, devoted to the pontificate: Tome to Flavian, Chalcedon, government of the West, Attila and Genseric.
• The Council of Chalcedon (451) — the council that received Leo's Tome as the rule of faith.
• Saint Gregory the Great (540-604) — the other pope “the Great”, doctor and pastor like Leo.
• Saint Prosper of Aquitaine (390-463) — disciple of Augustine, close collaborator of Leo in Rome.
• Saint Cyril of Alexandria (376-444) — the Greek doctor of the Incarnation, in correspondence with Leo.
• The Doctors of the Church in history — the category of Doctors to which Leo has belonged since 1754.