Gregorian chant, monophonic, or unison, liturgical music of the Roman Catholic Church, used to accompany the text of the mass and the canonical hours, or divine office. Gregorian chant is named after St. Gregory I, during whose papacy (590–604) it was collected and codified. Although popular legend credits Pope Gregory I with inventing Gregorian chant, scholars believe that it arose from a later Carolingian synthesis of Roman chant and Gallican chant. Gregorian chants were organized initially into four, then eight, and finally 12 modes.
