Guillaume de Machaut, renowned fourteenth-century French composer and poet, wrote the first polyphonic Mass and many other important musical works. Friend of royalty, prelates, noted poets and musicians, Machaut was a cosmopolitan presence in late medieval Europe. He also served as canon of the cathedral of Reims, an ancient and influential archiepiscopal see and the coronation site of French kings. This exploration of Machaut's life and work focuses on his music based on ecclesiastical chants: twenty-three motets, the David Hocket, and the Mass of Our Lady. The meaning of his music can often be understood through study of its context in fourteenth-century Reims. Machaut emerges as a composer deeply involved in the great crises of his day, one who skilfully and artfully expresses profound themes of human existence in ardent music and poetry.