The first system of learning music developed in the 11th century by Guido d'Arezzo. He assigned each note a name, ut, re, mi, fa, sol, and la (thus the origin of solfeggio), and designed the system of placing notes on horizontal lines to notate pitches (thus the origin of the staff). The Guidonian hand is another of his inventions, it is a system of assigning each part of the hand a certain note, thus, by pointing to a part of his hand, a group of singers would know which note was indicated and sing the corresponding note. a mnemonic device for remembering pitches named after the theorist Guido of Arezzo (ca. 991-d. after 1033). Each pitch and its hexachordal names was assigned to a knuckle of the hand. By moving up and down the fingers, one could call to mind the particular pitches that made up a melody. See hexachord.