The French composer Olivier Messiaen (1908-92) is a musician about whom most remains to be discovered. More than a decade after his death our knowledge of Messiaen is largely conditioned by what he said about himself in lectures and interviews, in his work as a teacher, and in the monumental seven-volume treatise that encompassed the whole of his composing world. But Messiaen's public documents conceal as much as they reveal, seldom explaining...