Machaut, Guillaume de [Guillaume de Machault] (b Reims, c.1300; d Reims, 1377). Fr. composer, cleric, poet, and diplomat. Secretary to John, Duke of Luxembourg from c.1323 to 1346. Later in service of King of Navarre, King of Cyprus, Duke of Berry, and others. Canon of churches at Reims, Verdun, and S. Quentin. Comp. motet for election of Archbishop of Reims, 1324. Outstanding practitioner of ars nova and among first to comp. polyphonic setting of poetry in fixed forms (ballade, rondeau, and virelai), to write in 4 parts, and to compose integrated setting of entire Ordinary of the Mass. Also among last to compose in the medieval forms of lai and dit. His most important works are probably the Messe de Notre Dame for 4 vv. and the Voir Dit (Tale of Truth), a collection of letters, lyrics, and song-settings (ballades and rondeaux) written in praise of a woman (Péronne d'Armentières). Machaut's works, which incl. 23 motets, have appeared in 3 complete edns., by Ludwig (1926, 1954), Schrade (1956), and Sylvette Leguy (Paris, from 1977).