My brother told me the other day there was no sex in Tristan. You don't have to be a close member of the family, or even very familiar with the opera, to know that he was not talking about whether or not Tristan and Isolde manage to achieve physical union before Melot and the King and the rest of the court interrupt them; I have always regarded that moment as the biggest coitus interruptus in music. Granted that they are `inter-assured of the mind', as Donne puts it, the question is academic. My brother decided somewhere around 1954 that there was no one to touch Mozart in opera and the view has sustained him into late middle age. His visit to Tristan had confirmed him in his view: I told him once that Tristan was the opera in which Wagner explores the idea that indulgence of sensual feeling is...