It was in the 14th century that musicians began assembling polyphonic settings of the parts of the ordinarium missae (Kyrie, Gloria, Credo, Sanctus, and Agnus Dei - and in those days often Ite missa est) to form a multipart cycle (Worship). In all likelihood, the settings of the mass from Barcelona, Tournai, and elsewhere were not the work of individual composers, but collections of works by a variety of authors. The Messe de Nostre Dame compo…