The first biography of the composer Gérard Grisey shows how the artist's sensuality and rigor came together to form the musical genre known as spectralism. The French composer Gérard Grisey (1946-98) changed the course of music history with his small but potent output. Labeled "spectral" music, his compositions looked to the physics of sound and the capacities of human perception for material and inspiration. Born in Belfort, Grisey was the son of a French Resistance veteran turned car mechanic and a homemaker. His first instrument was as humble as his background: the accordion. But Grisey rose from his provincial background to the heights of his profession. This first biography of Grisey traces his journey from rigid Catholicism to broader mysticism; his studies in Olivier Messiaen's legendary composition class; the development of the first "spectral" works in the 1970s; Grisey's stint teaching at the University of California at Berkeley, during which he suffered severe depression; the development of his late, post-spectral style; and his untimely death at the age of 52, shortly after completing his masterpiece on death, the Four Songs for Crossing the Threshold. Drawing on original archival research, interviews with more than fifty of Grisey's colleagues, friends, and lovers, and the study of previously overlooked sketches, this biography shows the delirium and form at the heart of Grisey's life and art—the structured sensuality that allowed him to revolutionize the music of the twentieth century.