Tantum ergo

The Latin text of "Tantum Ergo" sung to its traditional melody, which is a mode I Gregorian chant.

"Tantum ergo" is the incipit of the last two verses of Pange lingua, a Medieval Latin hymn composed by St. Thomas Aquinas circa A.D. 1264. The phrases "Genitori genitoque" and "Procedenti ab utroque" for the Blessed Trinity as the closing doxology are adapted from Adam of Saint Victor's sequence for Pentecost. The hymn's Latin incipit literally translates to "Therefore so great".

The singing of the Tantum ergo occurs during adoration and benediction of the Blessed Sacrament in the Catholic Church and other denominations that have this devotion. It is usually sung, though solemn is sometimes done, and permitted.