 What you are hearing now is an excerpt from a tenor mass that Guillaume Dufayi composed entitled Mise, c'est la fin chapelle. This tenor mass uses the ballade that we just heard earlier as the basis for the rest of the composition. Apparently, Dufayi is the first composer to take a secular song and use it in a sacred context. What's even more important is that Dufayi used this technique so well that it influenced composers for the next century.