For 10 points, name this 14th century poet-composer, known for the Notre Dame Mass.
His expressive use of changes in modality in works like Se mesdisans and Loyaute weil tous jours likely inspired the distinction between Musique artificielle and the Musique naturelle made by his student Eustache Deschamps. Amongst his works for religious occasions is his Bone pastor, qui pastores, which is his earliest dated work. Syllabic treatment of the text distinguishes his polyphonic rondeau Puis qu'en oubli while Douce dame jolie is likely the most famous amongst his virelais. Various musical inserts are strewn through his Le Voir Dit, and it was likely via the influence of works by Johannes de Muris and Philippe de Vitry that this man came to embody ars nova style. Those techniques were applied in a six movement work that ends with the isorhythmic movement Ite Missa, Est and is believed to be written for Reims Cathedral. That work is the first setting of Ordinary Mass associated with a single composer. For 10 points, name this 14th century poet-composer, known for the Notre Dame Mass. 
His expressive use of changes in modality in works like Se mesdisans and Loyaute weil tous jours likely inspired the distinction between Musique artificielle and the Musique naturelle made by his student Eustache Deschamps.
{Guillaume} de {Machaut}