Guido D’Arezzo

(c. 995–after 1033)

   The most famous music theorist of the late Middle Ages, he was active in Arezzo, Italy from 1025, with a visit to Rome probably about 1028 at the behest of Pope John XIX, who had heard of his teaching methods.

   In his treatise Aliae Regulae (c. 1020–1025) Guido proposes using a system of lines to express the pitch height of neumes (notes) more precisely than the old practice of using staffless neumes. He used two lines, one yellow to represent C and one red for F, because below those pitches occur the troublesome half-steps. In his Epistola de Ignoto Cantu (c. 1028, before 1033) Guido introduces his method of sight-singing by which a student abstracts pitch relations, relating them to the familiar hymn to St. John Ut {}queant laxis. Its first phrase begins with the syllable ut on the pitch C, the second phrase with the syllable re- (from resonare) on D, and so on until the familiar solfege pattern ut re mi fa so la is associated with locations in cognitive pitch space.

   These two innovations utterly revolutionized the use of musical notation in Europe and allowed the learning of newly composed music far faster than the rote methods which they replaced. In short, they underlie the entire polyphonic tradition of the west. In his Micrologus (1026–1032), the second most widely copied treatise on music after De Institutione Musica of Boethius, Guido discusses modes, polyphony, and the rhythmic relations in chant.