Saint Sixtus III and Saint Leo I – The Theotokos Celebrated and Preached (Doctrina Pontificia IV, nn. 19-29)

Saint Sixtus III (432-440) and Saint Leo I (440-461) are the two popes who immediately after Ephesus consolidate the Council’s definition theologically and liturgically. Sixtus III built the Basilica of Saint Mary Major in Rome, Leo I created one of the richest Marian theologies of the Western Fathers, especially in his Christmas Sermons.

Saint Sixtus III (432-440), n. 19

Sixtus III is the pope of the celebration of Ephesus. His most visible work is the rebuilding of the Basilica of Saint Mary Major on the Esquiline, in Rome, dedicated to the Mother of God immediately after the definition of Ephesus, the first great Marian shrine of Western Christendom. The inscription on the triumphal arch seeks to express the Ephesian definition in images: “Virgo Maria, tibi Xystus nova tecta dicavi / digna salutiferi talia dona tui” (Virgin Mary, to you I, Sixtus, have dedicated these new roofs / worthy gifts of your Savior).

Document n. 19 of Doctrina Pontificia IV recalls the pontifical text of Sixtus on Mary the Virgin Mother of God, in direct line with Ephesus.

Saint Leo I, the Great (440-461), nn. 20-28

Saint Leo I is one of the greatest doctors of Western Mariology. His Christmas sermons (numbered I, II, VI, VII, IX in the list of Doctrina Pontificia IV) are a perfect union of dogmatic depth and rhetorical eloquence. Documents nn. 20-28 cover:

• nn. 20-22: Epistles on Mary the Virgin Mother of God, doctrinal texts addressed to the bishops and to the Emperor
• n. 24 (Christmas Sermon I): Mary Virgin Mother, “Nativitas Christi ex intacta Virgine procedens”
• n. 25 (Christmas Sermon II): Mary ever virgin, Leo insists on virginity in partu: “intacta virginitas, quae nullum sensit corruptionem”
• n. 26-27 (Christmas Sermons VI and VII): Mary Virgin Mother, the twofold motherhood: carnal and spiritual
• n. 28-29 (Christmas Sermon IX and Epiphany): Mary immaculate Virgin Mother, an anticipation of the doctrine of the Immaculate Conception: “de Spiritu Sancto et Virgine natus est… nullum peccatum contraxit”

Key Text of Saint Leo I

“Haec enim generatio singularis est atque praecipua, quam nec Venus impulit, nec Lucina ministravit; sed Spiritus Sancti gratia perfecit. Haec nativitas non habet pari, quae divinae potentiae singulare miraculum est; propterea mater quidem non ignoratur, sed pater nusquam reperitur… Deus natus est in homine”

This birth is singular and supreme: Venus did not impel it, Lucina did not attend it, but the grace of the Holy Spirit accomplished it. This birth has no equal, for it is a singular miracle of divine power: therefore the mother is indeed known, but the father is nowhere to be found… God was born in man.

The Council of Chalcedon (451), n. 23

The fourth ecumenical council, presided over by the legates of Leo I, confirms the definition of Ephesus and adds the precision of the two natures in Christ, which reaffirms the divine motherhood of Mary: she is truly the Mother of the Word who is one single person with two natures, divine and human.

Further reading

Explore Mariology, Lumen Gentium chap. VIII, Redemptoris Mater, and the Postgraduate Program in Mariology.

See also: Theotokos: What “Mother of God” Means and Why It Is a Dogma