On Continuum this week will be a special program devoted Gregorian Chant, from a ten-CD set of the History of Music. Specifically, this volume covers musical Europe in the era of Gregorian unification. Gregorian chant developed mainly in western and central Europe during the 9th and 10th centuries, with later additions and redactions. Although popular legend credits Pope St. Gregory the Great with inventing Gregorian chant, scholars believe that it arose from a later Carolingian synthesis of Roman chant and Gallican chant. Performers include Anonymous 4, The Deller Consort, Ensemble Organum, and The Theatre of Voices. The recording used is Harmonia Mundi Volume 3 of the Century Collection.