How would a person who believes that musical works are universals account for instances of musical works which seem to imply that each performance of the same piece is always different, not only in the sense that all performances are different interpretations of the same score, but taking the examples of the arab "maqam", the indian "raga" or western jazz music, in which improvisation and sometimes a radical "mutation" of the work plays an important role, not accidental but essential to the performance of that work? Victor G.