What is the difference between a performance of Beethoven's Fifth Symphony and the symphony itself? What does it mean for musicians to be faithful to the works they perform? To answer this question, Goehr combines philosophical and historical methods of enquiry. She describes how the concept of a musical work emerged as late as 1800, and how it subsequently defined the norms, expectations, and behavior characteristic of classical musical practice. Out of the historical thesis, Goehr draws philosophical conclusions about the normative functions of concepts and ideals. She also addresses current debates amongst conductors, early-music performers, and avant-gardists.