When did Guido of Arezzo live?
Guido of Arezzo
991/992 – after 1033
Guido of Arezzo (also Guido Aretinus, Guido Aretino, Guido da Arezzo, Guido Monaco, Guido d'Arezzo, or Guy of Arezzo also Guy d'Arezzo) (991/992 – after 1033) was an Italian music theorist of the Medieval era. He is regarded as the inventor of modern musical notation (staff notation) that replaced neumatic notation. His text, the Micrologus, was the second most widely distributed treatise on music in the Middle Ages (after the writings of Boethius).