Jean de Muris (1290-1351) was a French philosopher and mathematician, best known for his promotion of ars nova over ars antiqua. Jury is out whether or not he actually wrote the "Speculum musicae". That voluminous work covers the entire range of musical knowledge of the time. It defends "Ars Antique" and attacks the "Ars Nova". Some say his authorship is unlikely, claiming that he was friends with Philippe de Vitry. Wikipedia
The definitive Wikipedia entry for Jean de Muris. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Jean_de_Muris
