The next stage in musical development was the important work of Guido of Arezzo (1030), a Benedictine monk of Pomposa, who wrote voluminously on musical theory and on the condition of the music of his time. It has been the rule with historians of music to attribute to Guido many discoveries which were doubtless made by other monks. Thus, he is credited with the invention of counterpoint, solmisation, the staff, the hexachord, the harmonic or Guidonian hand (see page 137), and the monochord. It is doubtful if research will ever be able to establish with accuracy exactly what we owe to Guido, but it is certain that he invented solmisation, by applying to the diatonic scale certain syllables of a hymn dedicated to John the Baptist, and they introduced new light and greater facility into the study of music. The modification of Guido's solmisation by the substitution of the more vocal syllable "do" for "ut," has been generally adopted; but the French, whose u is, by nature, sufficiently vocal, have not felt the need of this change. In the early middle ages the entire study and teaching of science and art, so far as it is known, was in the hands of the monks. They did their utmost to maintain a clear distinction between learned and popular music. Thus it happened that the folk-song, the utterance of the people, had its own line of development. The earliest attempts in writing learned music date from the time of Hucbald, a Benedictine monk of Flanders (840-930 A. D.) and of the staunchest of his followers, Jean Perotin; but Hucbald was not the inventor of counterpoint. The principle of imitation and the foundations of canon and fugue, were laid in Northern Europe; the first great school of composition was established in the Netherlands. Elsewhere in this work will be found a systematic and full treatment of this period. We need therefore only direct attention to that essay on the subject, which establishes the chronological connection of the Netherland masters with the great era of ecclesiastical music at Rome. The first Roman school owes its salient characteristics to the marked preference accorded Flemish singers in the choir of the Sistine Chapel, at Rome. The founder of the school was the Belgian, Constanzo Festa, who obtained a place in the choir, in 1516. His compositions and those of his pupils show distinct traces of the influence of the successors of Josquin des Près, but they possess sufficient individuality to prove the existence of innate genius of a very high order. Festa is believed to have been the first Italian composer who became a thorough master in counterpoint. But his Netherland tendencies did not prevent his foreshadowing that tenderness, purity and simplicity which distinguished the works of the great Italian masters who followed him.