How did John Dunstable compose? What principles did he follow when he sat down to plan a piece of music? Manfred Bukofzer's collected edition of his works is now twenty-six years old, and when we consider how little of his music is performed and known as sound, over a quarter of a century after its publication, it is plain that I am not the only person to find him an enigma. We hear a great deal more of Dufay's music: his concise, elegant phrasing, neat, sectional, easily apprehended construction, constant variety of texture and integrated, purposeful bass-lines make Dunstable seem obscure, remote and inhuman by comparison – for all his mastery of the long melodic vault and springing ribs of cross-rhythm. One can follow the harmonic logic and the bar-to-bar detail of rhythm and phrasing, but not the plan of the whole, with the one exception of the isorhythmic works, which accordingly are performed more frequently than his other sacred music. One feels much more at home with their clear, logical structure and steady, purposeful crescendo of rhythmic excitement.