About the fourth century the _neumes_ were in use in the Greek Church; they are spoken of by St. Gregory of Nazianzus. Certain modifications in them were introduced by the Lombards and Saxons. “They were specially in use from the eighth to the twelfth century,” says M. Coussemaker, in his learned work, “Histoire de l’Harmonie au Moyen Age,” “and consisted of two sorts of signs: some formed like commas, dots, or small inclined or horizontal strokes, which represented isolated sounds; others in the shape of hooks, and strokes variously twisted and joined, expressing groups of sound composed of various intervals. “These commas, dots, and inclined or horizontal strokes were the origin of the long notes, the breve and the semibreve, and afterwards of the square notation still in use in the _plain-chant_ of the Church. The hook-shaped signs and the variously twisted and joined strokes gave rise to the ligatures and connections of notes. “From the eighth to the end of the twelfth century--that is, during one of the brightest periods of musical liturgy--the _neumes_ were the notation exclusively adopted over the whole of Europe, both in ecclesiastical singing and also in secular music. From the end of the eleventh century, this system of notation was established in France, Italy, Germany, England, and Spain.” The chief modification to which the notation of music was subject at the end of the eleventh century is due to the monk Guido, of Arezzo. In order to facilitate the reading of the _neumes_, he invented placing them on lines, and these lines he distinguished by colours. The second, that of the _fa_, was red; the fourth, that of the _ut_, was green; the first and the third are only traced on the vellum with a pen. In order that the seven notes should be better impressed upon the memory, he gave as an example the three first lines of the Hymn of St. John the Baptist, in which the syllables _ut, re, mi, fa, sol, la_, corresponded to the signs of the gamut:-- “_Ut_ queant laxis _Re_sonare fibris _Mi_ra gestorum _Fa_muli tuorum, _Sol_ve polluti _La_bii reatum, Sancte Joannes.” The choristers, in singing this hymn, slightly raised the intonation of each of the italicised syllables, which were soon adopted for indicating six of the notes of the gamut. To supply the seventh, which was not named in this system, the barbarous theory of _muances_ (divisions) was introduced, and it was not until the seventeenth century the term _si_ was applied in France.