St. Leo the Great’s Teaching on Petrine Primacy

By Thomas V. Mirus ( bio - articles - email ) | Sep 01, 2026 | In Lives of the Popes

Previous installment

In the previous installment we looked at St. Leo the Great’s activities within his local sphere of authority in Rome and southern Italy. Before we proceed further to his government over the West and then the East, we need to understand what Leo believed and taught about his own authority as the Bishop of Rome.

In short, as Erick Ybarra details in his book on the papacy, and as even many Protestant scholars admit, the fundamental teachings of the First Vatican Council on the pope’s supreme, universal, and perpetual doctrinal and disciplinary authority are fully present in the words and policies of Leo, as found in his sermons and in his letters, especially to the Eastern churches.

St. Leo held that as a reward for his faith in Christ, St. Peter was given the office and the strength to be the rock on which the Church was founded. That steadfastness in faith was passed through Peter to the other Apostles, such that they both shared in and submitted to his authority. Just before the Passion, when the faith of all the Apostles would be tested, Jesus prayed for Peter specifically, “as though the stability of them all would be more secure if the spirit of him who was chief remained unconquered. So in Peter the courage of them all is strengthened, and the assistance of divine grace is so disposed that the steadfastness, which is imparted through Christ to Peter, is conveyed through Peter to the Apostles” (Sermon 4).

In Leo’s sermons given on the anniversary of his own consecration as bishop of Rome and on the feast of Sts. Peter and Paul, one is struck by his emphasis on the real personal presence and guidance of St. Peter continuing in the Roman see. The bishops of Rome are not only the vicars of Christ, but the vicars of St. Peter. Leo speaks of “not only the apostolic but also the episcopal dignity of blessed Peter who has not ceased to preside over his see and continues an ongoing sharing with the eternal Priest. For the solidity which he, having been made Peter the rock, received from Christ the rock, has passed on to his heirs” (Sermon 5). That is, Christ is the original Rock, who passed on His rock-ness to St. Peter, through whom “the universal Church has become a rock” (Letter 156).

Now he [St. Peter] performs the duties entrusted to him with wider scope and greater power, and executes all parts of his obligations and responsibilities in and with that person [his successor] through whom he has been honored. Hence if a right action is done by us or a right decision made, if anything is obtained from God in His mercy by daily prayers, it is a consequence of his good works and merits, whose power still survives and whose authority redounds in his see. (Sermon 3)

All the other bishops derive their authority from Christ through Peter:

Now the Lord willed that this responsibility should be the concern of all the Apostles in such a way that He has assigned it primarily to the most blessed Peter, head of all the Apostles; and intends that from him as from the head His gifts should be conveyed to the whole body, so that whoever dares to secede from the foundation of Peter may know that he is excluded from...the divine mystery. (Letter 10)

Thus the love of the whole Church “embraces Peter in Peter’s see” (Sermon 2).

The other bishops share with the pope the identical honor of the episcopal order, just as all the Apostles shared it with Peter. But Peter did not pass on his jurisdictional authority to the other Apostles or to all subsequent bishops—only to his successors in Rome, as Leo said on the anniversary of his consecration:

And so, dearly beloved, with reasonable obedience we celebrate today’s festival by such methods, that in my humble person he may be recognized and honored, in whom abides the care of all the shepherds, together with the charge of the sheep commended to him, and whose dignity is not abated even in so unworthy an heir. (Sermon 3)

The other Apostles had local authority, and passed it on to their successors, but Peter’s is universal: “Our care extends throughout all the churches” (Letter 5).

Of the immediate and direct authority of the pope over all Christians, Leo says:

And still out of the whole world, only Peter is chosen. He is put before the calling of all nations and at the head of all the Apostles and all the Fathers of the Church. Although in the people of God there are many bishops and many pastors, Peter in his own right governs all whom Christ rules as the head. Dearly beloved, God in his goodness has granted to this man a great and marvelous sharing in His power and if He wished that other rulers have something in common with him, he never gave anything to others unless he gave it through him. (Sermon 4)

The practical application of which is quite simple: “only that should be ratified in heaven which had been settled by the judgment of Peter” (Sermon 51).

This translates to a duty imposed on the bishop of Rome, for him to strengthen the brethren and defend the local authority of bishops throughout the world:

For although every shepherd presides over his own flocks with a particular responsibility...we have a duty which is shared with them all; in fact the function of each one is a part of our work: so that when men resort to the see of the blessed Apostle Peter from all quarters of the whole world, and seek from our bounty his love of the whole Church entrusted to him by the Lord, the greater our duty to everyone, the heavier we feel the burden to be which rests on our shoulders. (Sermon 5)

And it also means that the pope is obligated by Christ Himself to keep watch and expunge heresy and wickedness from anywhere it might crop up in the worldwide Church:

And if we do not repress such things with the vigilance we ought, we cannot excuse ourselves to Him who intended us to be watchmen, for permitting the pure body of the Church, which we ought to keep clean from every stain, to be defiled by contact with wicked schemers. (Letter 4)

St. Leo took these responsibilities with the utmost seriousness, as we shall see.

St. Leo’s preaching

Having quoted extensively from St. Leo’s sermons on the Petrine office, I may as well give you a glimpse of his preaching more generally. I highly recommend buying the collection of St. Leo’s sermons published by the Catholic University of America Press. The volume of his letters is more of historical interest, but the sermons are immediately accessible and applicable for today’s Catholics. His preaching is certainly majestic and profound, but also warm, direct, and recognizable as the voice of a pastor across the distance of millennia.

The sermons (which tend to be short) are largely organized according to the liturgical year. There are quite a number for Advent, Christmas, and Lent. Throughout the high liturgical seasons he would offer wonderful insights, which remain fresh today, about the incidents of the Gospel—Herod and the Magi, the Star of Bethlehem, the repentance of St. Peter and the despair of Judas, the Jewish authorities ironically bringing about the end of their own religion by using its holiest days to kill the Messiah, Simon of Cyrene, the weeping women, etc.

Often he preached to prepare his flock for special days of almsgiving, or of fasting in Lent and on the Ember Days of September and December. Fasting and almsgiving were integrally connected for him, since the idea was that you would take the money you would have spent on food and give it to the poor. His discussion of these practices is by no means overwhelmingly ascetical or intimidating, but that they are obligatory and necessary for Christians he leaves no doubt. He often remarks on how these special days are opportunities to get back on track and make up for any ways we may have slacked off in the pursuit of holiness.

And whatever the topic, Leo’s sermons, like his letters, are filled with references to and explanations of the correct doctrine of the Incarnation.

To give a brief sample of the richness of St. Leo’s preaching, I will quote a few of my favorite passages from his sermons. (In addition, on our sister podcast, Catholic Culture Audiobooks, James Majewski has narrated three of St. Leo’s sermons on Lenten fasting in an episode lasting about thirty minutes, using the CUA Press translation.)

Sermon 54, given on Palm Sunday:

Blessed Peter the apostle was the first to learn how much this humility bestowed upon all the faithful. When the violent storm of a cruel assault had overwhelmed him, he was turned by a sudden conversion to the restoration of his energy. He drew a remedy from the Lord’s example, and the trembling member returned at once to the firmness of its Head. This servant could not be greater than his Lord, nor this disciple greater than his Teacher, a Teacher who would not conquer the anxiety of human frailty without first experiencing fear—and conquering it.

Then “the Lord looked at Peter.” Standing amid the insults of priests, the lies of witnesses, the injuries of those who struck him and spat on him, he met the troubled disciple with his eyes, the same eyes with which he had foreseen that Peter would undergo a struggle. In so doing, the gaze of Truth entered into Peter, directed toward the place where the amendment of his heart was to be grounded. It was as if the Lord’s voice were resounding within him and saying: What are you thinking, Peter? Why do you withdraw into yourself? Turn to me, trust in me, “follow me.” This is the time for my Passion; the hour of your suffering has not yet come. Why do you fear what you yourself will also overcome? Let not the weakness which I have accepted disturb you. I was anxious for you, but you should not worry about me.

One of my favorite sermons by St. Leo is Sermon 95, on the Beatitudes:

“Blessed are those who mourn, for they will be comforted.” These mourners, dearly beloved, to whom eternal consolation is promised, do not share in the feelings of this world. Those laments which are poured out by the weeping of the whole human race do not make anyone blessed. The groans of the holy are of another kind. There is another cause of consecrated tears. Devout sorrow grieves at the sin of another or its own, not at what divine justice does. Religious sorrow grieves at what is committed by human iniquity, where the one doing the evil ought to be more wept for than the one suffering it. Their own malice directs the unjust to their penalty, but patience leads the just to glory.

In Sermon 18, anticipating the Ember Days of fasting in December, Leo reflected on how with the relatively recent end of the Roman persecutions, the devil had changed his strategy against the faithful, making it necessary for them to stay on guard by fasting:

After the sharp point of terror has been made dull, the cause of the struggle remains, a struggle which is stirred up terribly by the crafty enemy in the fury of persecution, but brought in all the more harmfully by the appearance of peace. When the battles are out in the open, the crowns are also evident. This, too, nourishes and inflames the strength of patience, that, when disaster is nearest, the promise is also at hand. After the public attacks of the wicked ones cease and the devil restrains himself from the slaughter and torture of the faithful, lest by the intensity of his cruelties there be a manifold increase of our triumphs, the raging adversary turns his bloodthirsty hatred to quiet treachery, and those he could not overcome with hunger and cold, with sword and fire, he will wear out with an easy life, he will snare with willfulness, inflame with ambition, and corrupt with luxury.

Sermon 37, on the Epiphany:

Christ loves the Childhood that he first took up in both soul and body. Christ loves childhood, the teacher of humility, the rule of innocence, the image of gentleness. Christ loves childhood, to which he directs the characters of older people, to which he brings back old age. Those whom he would raise up to an eternal kingdom he disposes to follow his own example.

So that we may be able to recognize clearly how this wonderful change might be accomplished and by what alteration we might return to the level of childhood, let blessed Paul teach us and say, “Do not be made into children with respect to your senses, but become very little with respect to wickedness.” It is not to the amusements of childhood and to our imperfect beginnings that we must return, but we must extract from childhood something fitting for later years. May disturbances pass speedily and peace return quickly. May there be no memory of offenses, no desire for importance, but only a love for sharing things together and a natural equality. It is a great good not to know how to harm and not to have a taste for malice. To inflict and to pay back injury belongs to the wisdom of this world, but “to repay evil for evil to no one” represents the childhood of Christian self-possession.

Sermon 45:

Consequently, as the just soul walks along the way of truth, so the gentle soul walks along the way of mercy. Yet these roads are never divided, as if parts of these virtues were sought by different paths, as if it were one thing to grow in mercy and another to progress in truth. People are not merciful if they are strangers to truth, nor are they capable of justice who are beyond the reach of compassion. Those who are not endowed with both virtues enjoy neither. Love is the power of faith; faith is the strength of love. Only then is the name true and the fruit true of both when the union remains intact.