Guido d’Arezzo

Guido d’Arezzo (born c. 990, Arezzo? [Italy]—died 1050, Avellana?) was a medieval music theorist whose principles served as a foundation for modern Western musical notation. Educated at the Benedictine abbey at Pomposa, Guido evidently made use of the music treatise of Odo of Saint-Maur-des-Fossés and apparently developed his principles of staff notation there. He left Pomposa in about 1025 because his fellow monks resisted his musical innovations, and he was appointed by Theobald, bishop of...