Machaut, Guillaume de (1300–1377)

French poet and composer. Born in Champagne, he was in the service of John of Bohemia for 30 years and, later, of King John the Good of France. He gave the ballade and rondo forms a new individuality and ensured their lasting popularity. His Messe de Nostre Dame about 1360, written for Reims Cathedral, is an early masterpiece of ars nova, ‘new (musical) art’, exploiting unusual rhythmic complexities.