From Gallican Chant to Dufay. The essays collected here, written between 1989 and 2007, concern different aspects of medieval music in France from the 8th century up to the mid-15th, covering a wide range of subjects Gallican survivals in Gregorian chant, the Cluniac and Cistercian versions of it, rhythm and variation in trouvre song, the origins of Aquitanian polyphony, the evolution of counterpoint up to the 13th century, the intellectual novelty of the Parisian motet, the mathematical underpinning of the Ars nova and the presence of triads in the music of Dufay.