Sacris solemniis

Sacris Solemniis is a hymn written by St. Thomas Aquinas (1225–1274) for the Feast of Corpus Christi (now called the Solemnity of the Holy Body and Blood of Christ). The strophe of Sacris solemniis that begins with the words "Panis angelicus" (bread of angels) has often been set to music separately from the rest of the hymn. Most famously, in 1872 César Franck set this strophe for voice (tenor), harp, cello, and organ, and incorporated it into his Messe à trois voix Opus 12. The hymn expresses the doctrine that the bread and wine are changed into the Body and Blood of Christ. In the Roman Catholic tradition the concept of transubstantiation is presented as an explanation of how this change happens.

The phenomenon whereby the strophe of Sacris solemniis that begins with the words "Panis angelicus" is often treated as a separate hymn has occurred also with other hymns that Thomas Aquinas wrote for Corpus Christi: Verbum supernum prodiens (the last two strophes begin with "O salutaris Hostia"), Adoro te devote (the strophe beginning with "Pie Pelicane, Jesu Domine"), and Pange lingua gloriosi (the last two strophes begin with "Tantum ergo", in which case the word ergo ["therefore"] makes evident that this part is the continuation of a longer hymn).