Ite, missa est

Ite, missa est, meaning “go, the Mass is ended”, is the formal dismissal marking the end of the Mass ritual, and one of the most ancient formulae of the Roman rite. It is technically part of the Ordinary, because it is common to most Masses, and some of the earliest polyphonic settings of the Mass Ordinary from the 14th century (e.g. the Missa de Nostre Dame by Guillaume de Machaut and the anonymous Masses of Toulouse and Tournai) provide polyphony for this text. Fifteenth century polyphonic settings of the Mass Ordinary, however, include only the Kyrie, Gloria, Credo, Sanctus, and Agnus Dei, leaving the dismissal to be delivered in plainsong, as it is here in this Mass for St. Donatian. The deacon sings the brief but florid dismissal phrase, with its extended melisma on the second syllable, to which the choir responds with an echo of the same melody, substituting the words Deo gratias or “Thanks be to God.”

Anna DeLoi with M. Jennifer Bloxam

To learn more about the Ite, missa est, see:
Sherr, Richard. 2001 “Ite missa est.” Grove Music Online. 1 Aug. 2018.
Jungmann, Joseph A. The Mass of the Roman Rite: Its Origins and Development, Vol. 2. New York: Benzinger Brothers, 1955. See in particular pp. 432-37.
Hiley, David. Western Plainchant: A Handbook. Oxford: Oxford University Press, 1993. See in particular pp. 116-20