A Collect is the first of the Proper prayers of the Mass, consisting of a single long sentence said or recited by the celebrant prior to the Epistle. Its text, which varies according to the feast or season, is usually comprised of five sections: an invocation to God, a clause describing some aspect of God, a petition to Him (often in the name of the saint whose feast day it is), the goal of the petition, and a conclusion (these sections are labeled in the score). In a Mass for St. Donatian sung entirely in chant, therefore, the saint would not be named until this point in the service; Obrecht’s choice of a plainsong cantus firmus for the Kyrie that invokes St. Donatian thus insures that the saint is made present immediately after the opening.
The Collect is introduced by the celebrant’s recitational invitation to prayer (Dominus vobiscum). The prayer itself is delivered by the celebrant using a simple reciting tone designed for maximum intelligibility.
To learn more about the Collect, see:
Fortescue, Adrian. “Collect.” Catholic Encyclopedia Online. http://www.newadvent.org/cathen/04103a.htm
Harper, John. 2001 “Collect.” Grove Music Online. 16 Jul. 2018. www.grovemusiconline.com