Jacob of Liège
Jacob of Liège might also refer to Pope Urban IV
Jacob of Liège, aka Jacobus Leodiensis or Jacques de Liège, is believed to have written the Speculum Musicae (The Mirror of Music) during the second quarter of the 14th century.
This, the largest surviving medieval work on music, was previously attributed to Jean de Muris. It now seems likely that it was written by someone with the name Jacobus, who was probably born in the diocese of Liège, before going to study in Paris in the late 13th century, and who returned to Liège to complete the final two books of his seven-volume treatise, Speculum musicae.[1]