I. Guido, or Gnido d'Arezzo, a Benedictine monk, born at Arezzo near the end of the 10th century. He early occupied himself in devising new methods of writing and teaching music. Instead of a group or tetrachords like the Greek method, or of heptachords such as Gregory adopted, he proposed a new system, consisting of hexachords. The six syllables by which he designated his notes were suggested to him, it is said, by a Latin hymn to St. John:

UT queant laxis REonare fibris MIra. gestorum FAmuli tuorum, SOLve polluti LAbii reatum, Sancte Johannes.

To the seventh note, si, he gave no name, and for a long time it continued to be called b. Guido's new method of solmization attracted much attention. Whereas ten years had been required to learn to read music, a chant could be mastered by this method in a few days, and a year sufficed to make a skilful singer. Pope John XVIII. (1024-'33) invited Guido to his court and was greatly pleased with his plan. Guido not only facilitated the reading of music, but simplified the manner of writing it. Since St. Gregory, attempts had been made to improve musical notation. Already the seven letters, formerly written on one line, were placed on parallel lines, to indicate the rising and falling of the voice. Guido, instead of repeating the letter, wrote it at the beginning of the line, and each time it occurred marked a point on the line. He ended by placing the points within the lines, thus rendering the written composition more compact. Guido has the fame of being the inventor of the modern gamut.

II. See Bruni, Leonaedo.

III. Pietro, an Italian writer, born in Arezzo in 141)2, died in Venice in 1557. He was the natural son of a gentleman named Luigi Bacci, and was brought up by his mother, Tita. While still very young he was obliged to leave his native city on account of having written a sonnet against indulgences, and went to Perugia, where for a long time he supported himself as a bookbinder. Thence he went on foot to Rome, and obtained employment in the service of Popes Leo X. and Clement VII.; but, having composed 16 sonnets for as many licentious designs of Giulio Romano, he was forced to retire to Arezzo (1524), and soon afterward to the court of Giovanni de' Medici. At length he returned to Rome, where he made love to a cook, and composed a sonnet in her praise. A Bolognese gentleman, Achille della Volta, was a rival lover, and finding Aretino one day alone, stabbed him five times in the breast and maimed his hands (1525). Displeased with the refusal of the pope to punish his assailant, Aretino sought once more the court of Giovanni de' Medici. This prince having been killed in battle in 1526, Aretino resolved to have no more protectors, but to support himself by his pen.

With this view he went to Venice in 1527, where he chiefly passed the rest of his life, becoming reconciled with the pope in 1530. His end was peculiar. Having heard of some excesses of his sisters, he found them so comical that he threw himself back in his chair laughing, fell over backward, and was killed.