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 why a work was written or what complexities went into its making. The composer was similarly reticent about his private life. This is the first book to explore the world that Messiaen was at pains to keep hidden. Based upon unprecedented access to Messiaen's private archive granted to the authors by the composer's widow, Yvonne Loriod-Messiaen, Peter Hill and Nigel Simeone trace the origins of many of Messiaen's greatest works and place them in the context of his life, from his years at the Paris Conservatoire and his passionate first marriage to Claire Delbos through the immense achievements of his final decades.