The poet-musician Notker Balbulus (ca. 840-912), a monk in the Swiss monastery of St. Gall, popularized sequences, poems sung during Mass following--as a sequence to--the Alleluia.

Born not far from St. Gall, Notker, or Notger, Balbulus lost his father in early childhood and was brought up by an old soldier who had served in Charlemagne's army. As a young boy, Notker went to study at St. Gall, then entered the monastery as a monk, and later became its librarian. Always interested in literature, he there found congenial poet friends and like them wrote historical, poetic, and musical works. As a historian, he collected a book of legal deeds and other official documents of his monastery, adding some occasional poems, expanded the existing book of lives of the saints, and chronicled the deeds of Charlemagne. Most of his poetic works were collected in his Liber hymnorum (ca. 860-887). Though...