For chorus of four part mixed voices. The original published score states with organ accompaniment ad libitum. Messiaen later in life designated the work for mixed choir a cappella, but the score was not revised. Thus the piece isoften performed without accompaniment. The text is by St. Thomas Aquinas (1225-1274), used as an antiphon for the feast of Corpus Christi.

• O Sacrum Convivium!