Perhaps a purely theoretical work, Bach's Art of the Fugue has intrigued performers for centuries. What instruments should play it? Should it be left unfinished? How to shape such an uninteresting theme? The Juilliard String Quartet answers all these questions, leaving the work unfinished but their interpretation complete, startlingly modern and a joy to hear. Play Contrapunctus IX for a taste of a whirlwind of intersecting melodic lines at a devilish speed.