In a 1907 letter to Stefi Geyer (the young violinist for whom he wrote the First Violin Concerto), Bartók writes: “It’s not the body that’s mortal and the soul that’s immortal, but the other way around. The soul is transitory and the body (that is, matter) is everlasting! . . . The body, as matter, is ‘immortal’ indeed, for matter in this world is never lost; it only changes its form” (Béla Bartók Letters, 76, emphasis in the original). Bartók’s Bluebeard’s Castle (1918; first version, 1911) can be read as an attempt to give expression to the idea of “immortal,” as well as agential, matter, beginning with the castle itself. The drama of the opera revolves around the opening of the castle’s seven doors by the light-bringing human characters, Judith and Bluebeard, leading to the inner chamber. Here Judith becomes absorbed into the object world of the castle as Bluebeard simultaneously becomes swallowed by the closing “night forever” of the opera’s final curtain. The sweating, weeping, sighing, bleeding, and shrieking castle was originally conceived by librettist Béla Balázs as the third character of the opera: it is both a noisy environment into which the characters are thrust and a sonic agent in itself, its “voice” (and the discordant voices of its objects) as central to the opera as those of its human characters.