ca. 991 - May 17, 1050? (Both his date of birth and date of death are in question)

Guido of Arezzo (possibly to be identified with Guido de St Maur des Fosses), a musician who lived in the 11th century. He has by many been called the father of modern music, and a portrait of him in the refectory of the monastery of Avellana bears the inscription Beatus Guido, inventor musicae. Of his life little is known, and that little is chiefly derived from the dedicatory letters prefixed to two of his treatises and addressed respectively to Bishop Theodald (not Theobald, as Burney writes the name) of Arezzo, and Michael, a monk of Pomposa and Guido's pupil and friend. Occasional references to the celebrated musician in the works of his contemporaries are, however, by no means rare, and from these it may be conjectured with all but absolute certainty that Guido was born in the last decade of the 10th century. The place of his birth is uncertain in spite of some evidence pointing to Arezzo; on the title-page of all his works he is styled Guido Aretinus, or simply Aretinus. At his first appearance in history Guido was a monk in the Benedictine monastery of Pomposa, and it was there that he taught singing and invented his educational method, by means of which, according to his own statement, a pupil might learn within five months what formerly it would have taken him ten years to acquire. Envy and jealousy, however, were his only reward, and by these he was compelled to leave his monastery- "inde est, quod me vides prolixis finibus exulatum," as he says himself in the second of the letters above referred to. According to one account, he travelled as far as Bremen, called there by Archbishop Hermann in order to reform the musical service. But this statement has been doubted. Certain it is that not long after his flight from Pomposa Guido was living at Arezzo, and it was here that, about 1030, he received an invitation to Rome from Pope John XIV. He obeyed the summons, and the pope himself became his first and apparently one of his most proficient pupils. But in spite of his success Guido could not be induced to remain in Rome, the insalubrious air of which seems to have affected his health. In Rome he met again his former superior, the abbot of Pomposa, who seems to have repented of his conduct, and to have induced Guido to return to Pomposa; and here all authentic records of Guido's life cease. We only know that he died, on the 17th of May 1050, as prior of Avellana, a monastery of the Camaldulians; such at least is the statement of the chroniclers of that order. It ought, however, to be added that the Camaldulians claim the celebrated musician as wholly their own, and altogether deny his connexion with the Benedictines.

The documents discovered by Dom Germain Morin, the Belgian Benedictine, about 1888, point to the conclusion that Guido was a Frenchman and lived from his youth upwards in the Benedictine monastery of St Maur des Fosses where he invented his novel system of notation and taught the brothers to sing by it. In codex 763 of the British Museum the composer of the "Micrologus" and other works by Guido of Arezzo is always described as Guido de Sancto Mauro.

There is no doubt that Guido's method shows considerable progress in the evolution of modern notation. It was he who for the first time systematically used the lines of the staff, and the intervals or spatia between them. There is also little doubt that the names of the first six notes of the scale, ut, re, mi, fa, sol, la, still in use among Romance nations, were introduced by Guido, although he seems to have used them in a relative rather than in an absolute sense. It is well known that these words are the first syllables of six lines of a hymn addressed to St John the Baptist, which may be given here:

In addition to this Guido is generally credited with the introduction of the F clef. But more important than all this, perhaps, is the thoroughly practical tone which Guido assumes in his theoretical writings, and which differs greatly from the clumsy scholasticism of his contemporaries and predecessors.

The most important of Guido's treatises, and those which are generally acknowledged to be authentic, are Micrologus Guidonis de disciplina artis musicae, dedicated to Bishop Theodald of Arezzo, and comprising a complete theory of music, in 20 chapters; Musicae Guidonis regulae rhythmicae in antiphonarii sui prologum prolatae, written in trochaic decasyllabics of anything but classical structure; Aliae Guidonis regulae de ignoto cantu, identidem in antiphonarii sui prologum prolatae; and the Epistola Guidonis Michaeli monacho de ignoto cantu, already referred to. These are published in the second volume of Gerbert's Scriptores ecclesiastici de musica sacra. A very important manuscript unknown to Gerbert (the Codex bibliothecae Uticensis, in the Paris library) contains, besides minor treatises, an antiphonarium and gradual undoubtedly belonging to Guido.