Guido of Arezzo
In the 12th century, a development in teaching and learning music in a more efficient manner had arisen. Guido of Arezzo's alleged development of the Guidonian hand, more than a hundred years after his death, allowed for musicians to label a specific joint or fingertip with the gamut (also referred to as the hexachord in the modern era). Using specific joints of the hand and fingertips transformed the way one would learn and memorize solmization syllables. Not only did the Guidonian hand become a standard use in preparing music in the 12th century, its popularity grew more widespread well into the 17th and 18th century. The knowledge and use of the Guidonian hand would allow a musician to simply transpose, identify intervals, and aid in use of notation and the creation of new music. Musicians were able to sing and memorize longer sections of music and counterpoint during performances and the amount of time spent diminished dramatically.
Guidonian hand
Exact notation to the hexachord system can be found in a reproduction of "Ameri Practica artis musice" (1271), or in the 1784 source "Scriptores ecclesiastici de musica sacra potissimum".