The danger of that - and there's a grave danger that I, myself, have to be very aware of - is that you become so involved and intrigued in the language that sometimes you lose track that that is only a means to an aesthetic experience that the listener has to get.

Though he gave his last public concert before the age of forty he continued writing music for another half-century and beyond. His performances of works by avant-garde composers and his own innovative and even shocking pieces made him a cause célèbre on both sides of the Atlantic.