Guido of Arezzo

Guido of Arezzo (Italian: Guido d'Arezzo; c. 991–992 – after 1033) was an Italian music theorist and pedagogue of High medieval music. A monk from the Order of Saint Benedict, he is regarded as the inventor—or by some, developer—of the modern staff notation that had a massive influence on the development of Western musical notation and practice. Perhaps the most significant European writer on music between Boethius and Johannes Tinctoris, Guido wrote the Micrologus, the most widely distributed medieval treatise on music, after Boethius's De institutione musica.

Biographical information on Guido is only available from two contemporary documents; though they give limited background, a basic understanding of his life can be unravelled. By around 1013 he began teaching at Pomposa Abbey, but his antiphonary Prologus in antiphonarium and novel teaching methods based on staff notation brought considerable resentment from his colleagues. He thus moved to Arezzo in 1025 and under the patronage of Bishop Tedald of Arezzo he taught singers at the Arezzo Cathedral. Using staff notation, he was able to teach large amounts of music quickly, and he wrote the multifaceted Micrologus, attracting attention from around Italy. Interested in his innovations, Pope John XIX called him to Rome. After arriving and beginning to explain his methods to the clergy, sickness sent him away in the summer. The rest of his life is largely unknown, but he settled in a monastery near Arezzo, probably one of the Avellana of the Camaldolese order.