A monk known as Guido of Arezzo made some major breakthroughs in musical notation. One of these is the introduction of the solfege system. Solfege is a system in which syllables are used to represent different tones of the scale. These syllables, which you probably already know, are: do, re, mi, fa, so, la, ti, do. This genius monk also created a notation system that was a basic version of the one that we use now. When he demonstrated his system to others, they were astonished that they could sing a tune previously unknown to them by "singing at sight".