Guillaume Dufay (ca.1390-1474) Missa Ecce Ancilla Domini Figure major of the music of the 15th century, Guillaume Dufay occupies a central place in the evolution of polyphony at the hinge of the Middle Ages and the Renaissance. La Missa Ecce Ancilla Domini is part of the tradition of masses built from pre-existing material, here linked to the Marian text of the Annunciation. In a writing of great clarity, Dufay deploys a subtle balance between melodic lines and polyphonic architecture.