 This mass is an extended fantasia on the tune, using the melody in all voices and in all parts of the mass, in elaborate and ever-changing polyphony.One of the high points of the mass is the "et incarnatus est" section of the Credo, where the texture becomes homophonic, and the tune appears in the topmost voice; here the portion which would normally set "Sing, O my tongue, of the mystery of the divine body" is instead given the words "And he became incarnate by the Holy Ghost from the Virgin Mary, and was made man.