in the 20th-century symphonic repertoire, both sacred and secular, continued to progress through the music of marcel dupré, maurice duruflé, and herbert howells. other composers, such as olivier messiaen, györgy ligeti, jehan alain, jean langlais, gerd zacher, and petr eben, wrote post-tonal organ music. messiaen's music in particular redefined many of the traditional notions of organ registration and technique.