"In illo uno unum": detailed explanation of the Papal Coat of Arms and Motto chosen by Leo XIV for his Pontificate

The coat of arms and the motto of Pope Leo XIV reflect his membership in the Order of Saint Augustine and the spiritual vision of his papacy.

Pontifical coat of arms of Pope Leo XIV

The shield is diagonally divided into two sections:

Top left: Against a blue background, a white lily stands out, symbolising the purity and grace of the Virgin Mary. This element refers to Pope Leo XIII, whose papal coat of arms also features the "fleur-de-lis." In this way, Pope Leo XIV inserts himself into the venerable tradition of Marian devotion, already evident during his first visit to the Basilica of Our Mother of Good Counsel. Other recent papal coats of arms with lilies are those of John XXIII and Paul VI. It happens that the papal election took place on the same day that a Marian devotion is celebrated: Our Lady of the Rosary of Pompeii and, in the Order of Saint Augustine, Our Lady of Grace.

Bottom right: it presents an image on a light background that recalls the Order of Saint Augustine: a closed book with a heart pierced by an arrow. The image recalls the experience of Saint Augustine's conversion, which he himself referred to with the words "vulnerasti cor meum verbo tuo," "You have pierced my heart with your Word." Likewise, the union of the heart with the book refers to other realities of Christian and Augustinian life: the need for a deep inner life, along with the call to know the Truth and the voice of God, through the reading and study of the Word.

Mitre instead of tiara

Just like Benedict XVI and Francis, Leo XIV displays the episcopal mitre on his shield, instead of the papal tiara, which had been used until John Paul II. It is a gesture that continues the one already undertaken by Paul VI, by ceasing to use the tiara. Moreover, it happens that the surname of Leo XIV is Prevost (in modern French it would be Prévôt), a word that corresponds to "provost" (from Latin praepositus), which designates the person placed at the forefront to lead a community. Something that Prevost himself alluded to in his doctoral thesis on the role and authority of the prior in the Order of Saint Augustine. He quoted a play on words from the saint of Hippo: "Praeposti sumus, et servi sumus; praesumus, sed si prosumus" ("We are in charge and we are servants; we are the first if we are the last; we are in command if we are of use"). Likewise, Leo's papal coat of arms, like that of his predecessors, is essentially the episcopal coat of arms he had before being elected Roman Pontiff. Therefore, one can see a vocation of the Bishop of Rome who collaborates with the other bishops of the world and presides over them in charity.

About the motto "In illo uno unum"

The motto chosen by the Pope is his own episcopal motto: "In Illo uno unum," a phrase taken from Saint Augustine's commentary on Psalm 127, which means "In Him who is One (Christ), we are One." The literal expression of the Bishop of Hippo within which the motto is inserted is as follows: "These Christians, with their Head, who ascended to heaven, are one Christ; it is not He one and we many, but, being many in that one, we are one."

This motto emphasises the unity of Christians in Christ and the communion within the Church, and expresses the profound Christocentric vision of the unity of the Church: only in Him can true unity be found.