GUIDO, D' AREZZO, who stands very prominently in all musical histories as the discoverer of the path which led to the invention of the modern system of notation, and of the true art of teaching singiog, together with other improvements, was born at Arezzo in Tuscany, towards the end of the 10th century. When young he entered the Benedictine monastery of that city, probably as a chorister, and after wards became a monk of the order. There he first conceived a new method of writing music, and of instructing in the art ; and having well digested his plan, he there also carried it into effect, at a school opened by him for the purpose. On the old system, it is stated, ten years were consumed in acquiring a knowledge of plain song only ; Guido's, we are told, reduced the years to as many months. His success excited, as commonly happens, the jealousy of his brethren, and he was driven to seek an asylum in another monastery. This we learn from his letter to Michael, a brother monk ; and from the same it appears that the fame of his school having reached the ears of Pope John X1X., he was invited to Rome, and had the honour not only of explaining to the sovereign pontiff the nature of his new method, but of teaching the holy father to sing by it.
On his return from Rome he visited the abbot of Pomposa, in the duchy of Ferrara, who persuaded him to settle in that place. Here it was he wrote his ' Micrologus; or brief discourse on music, in which most of his inventions are described, as well as his method of instruc tion. But his doctrine of aolmisation, or the use of the syllables ut,
re, mi, &c., is not mentioned in that work ; it is explained in a small tract under the title of 'Argumentum nevi Cantua inveniendi.' The date of his death is unknown : it was probably about the middle of the 11th century.
To Guido we are indebted for the invention of the Staff, namely, the lines and spaces ; for the reformation of the Scale, as also of the mode of notation, and for the art of Solmisation. Musical instruments being, it is to be presumed, very imperfect in his day, he taught his scholars to sing by a monochord, for the proper division of which he gives precise rules : but his;reliance was on a system of hexa chords, or scales of six notes, which he substituted for the ancient tetrachords, and on the syllables he applied to the different sounds. To this invention Guido is mainly indebted for the fame he has so long enjoyed. The art of counterpoint, and other important dis coveries made before and after his time, have been attributed to him, but the assertions which have assigned to the ingenious ecclesiastic that to which he has no title, and never claimed, have been fully refuted.