Olivier Messiaen (1908-1992) was the most influential composer for the organ in the 20th century. Shaped by French tradition as well as the innovations of Debussy, Stravinsky, and Bartók, Messiaen developed a unique style that would become his signature. Using Messiaen's own analytical and aesthetic notes as a point of departure, Jon Gillock offers detailed commentary on the performance of Messiaen's 66 organ works. Gillock provides background information on the composition and premiere of each piece, a translation of Messiaen's related writings, and a systematic explanation of performance considerations. Gillock also supplies details about the organ at La Trinité in Paris, the instrument for which most of Messiaen's pieces were imagined.