Lauda Sion

It was written by St. Thomas Aquinas around 1264, at the request of Pope Urban IV for the new Mass of this feast, along with Pange lingua, Sacris solemniis, and Verbum supernum prodiens, which are used in the Divine Office.

The hymn tells of the institution of the Eucharist and clearly expresses the belief of the Roman Catholic Church in transubstantiation and in Real presence, that is, that the bread and wine truly become permanently and irreversibly the Body and Blood of Christ when consecrated by a validly-ordained priest or bishop during the Mass.

The fact that the hymn had been composed for the Holy Mass is testified by the sixth stanza: Dies enim solemnis agitur / In qua mensæ prima recolitur / Hujus institutio.

[1] Lauda Sion is one of only four medieval sequences which were preserved in the Roman Missal published in 1570 following the Council of Trent (1545–1563) by Will of Saint Pius V—the others being Victimae paschali laudes (Easter), Veni Sancte Spiritus (Pentecost), and Dies irae (requiem masses).

According to Dom Guéranger, Lauda Sion: it is here that the utmost power of a Scholasticism, not crude and truncated, like that of today, but juicy and complete, like that of the Middle Ages, was able to bend the rhythm of the Latin language to the clear exposition and demand a dogma, as abstract for the theologian as it is sweet and consoling for the heart of the faithful.