Since the 15th century, the two last strophes of the Eucharistic hymn "Pange lingua" of St. Thomas Aquinas are sung before the administration of the Eucharistic blessing. Valentin Rathgeber has published only 6 Tantum ergo in his Opus XIII. These compositions display the form of strophic chants. Each Tantum ergo ends with an Amen in two to four bars.