Even in Germany and Austria, where he enjoyed his greatest successes, Franz Schreker remains a shadowy figure, slowly being rediscovered as Alexander Zemlinsky (1872-1942) has been. Like several lesser eminences born in the wake of Richard Strauss, Schreker conducted and taught as well as composed. Just before World War I, and briefly after, he became a musical celebrity, but without the controversy that surrounded his lifelong friend Arnold Schoenberg. After the war, both taught in Berlin -- Schreker as director of the storied Hochschule für Musik starting in 1920, Schoenberg...