Guido D’Arezzo, << GWEE doh dah REHT tsoh >> (995?-1050?), a Benedictine monk, was an Italian music teacher. He introduced the four-line staff, and is credited with naming the first six notes of the scale ut, re, mi, fa, sol, and la. (Later, do was substituted for ut. ) These reforms made the teaching of music much easier. Pope John XIX liked Guido’s musical ideas, and helped make them popular.
