During Obrecht’s time, the Sanctus was sung during the Canon of the Mass, while the celebrant silently said the prayers and performed the ritual actions that resulted in the miracle of the Transubstantiation, the transformation of the Host into the Body of Christ. It is the concluding portion of the Preface, the first of the Eucharistic prayers that comprise the Canon. The Preface was intoned by the celebrant, and was tailored to the liturgical occasion; all prefaces, however, conclude with a phrase that prepares the words of the angels as told in Isaiah 6:3, “Holy, Holy, Holy …” which become the choral continuation of the Preface: “Sanctus, Sanctus, Sanctus …”

Obrecht binds this Sanctus setting to the rest of his Mass setting for St Donatian in two ways: he commences with the by now familiar headmotive, and he once again takes as his cantus firmus the suffrage antiphon O beate pater Donatiane. The angelic choir’s communal praise of the Lord is thus combined with the communal plea for saintly intervention, emphasizing the purpose of Obrecht’s composition as musical prayer for a soul’s salvation. Especially noteworthy is the passage where bass joins tenor in an imitative treatment of the saint’s name and the name of Christ, foregrounding their presence in the midst of the angelic salutation.

Obrecht’s Sanctus is sung by Cappella Pratensis from the original notation as preserved in the choirbook Jena, Universitatsbibliothek, Ms 32.

For more information, see:
Crocker, Richard L., and David Hiley. 2001 “Sanctus.” Grove Music Online. 30 Jul. 2018.
Hiley, David. Western Plainchant: a Handbook. Oxford: Oxford University Press, 1993. See in particular pp. 161-65.
Strohm, Reinhard. Music in Late Medieval Bruges. New York: Oxford University Press. 1985. See in particular pp. 146-48.
Wegman, Rob C. Born for the Muses: The Life and Masses of Jacob Obrecht. New York: Oxford University Press, 1994. See in particular pp. 169-74.