In 2009, the opera singer Cecilia Bartoli released the album Sacrificium , a sleek collection of music that castrati sang in the eighteenth century. Castrati—adult men castrated before puberty in order to retain their high soprano voices—had extraordinary breath control, a pure tone, and an unusually flexible vocal instrument. In promotional materials, Bartoli characterized Sacrificium as “a work dedicated to ‘castratos’ and the music that their magic voices inspired … The title of the album refers to the sacrifice castratos did for the sake of music stance lay in the production of voice and the technique necessary to produce the required sound. This essay uses the castrato to shift the conversation in this special issue of NLH from song to the materials of song, i.e., voice and sound, and to position the human voice as instrumentalized matter. The castrato serves as a site for unpacking very unstable notions of voice, matter, instrument, and machine. Because the castrato voice was so explicitly made by surgeons, teachers, and the singers themselves, it foregrounds the technical practices and materials that make any song possible. This pushes against critical discussions of song that too frequently begin from poetry and attempt to explain why song differs from and exceeds language. Shifting the terms from song to singing and then to voice serves as a corrective to a Western philosophical tradition that has for centuries been invested in the return of an Arcadian ideal: an originary fusing of word and song, torn apart by modernity. The castrato voice puts pressure on that fantasy of a time when lyric and song were one, on the spiritualized concept of the voice that comes with it. An alternative reading to this philosophical understanding of the voice, which runs through Plato and Aristotle to Augustine and early modern anatomists, and finally to Freud and Derrida, arises when we situate the voice as sounding instrument alongside other materialities such as organs, scientific instruments, and body parts.