This essay examines the role of mathematical logic in Jacques Roubaud’s response to his wife’s death in The Plurality of Worlds of Lewis. At the heart of his thinking is a basic problem: each poem addresses the “you” of his beloved wife, yet that “you” no longer has a referent in the world. Refusing the consolation of the traditional elegy, Roubaud turns instead to David Lewis’s notorious book of formal logic, On the Plurality of Worlds, in which Lewis makes a mathematical argument in favor of the existence of multiple worlds. If Alix Cleo no longer exists in this world, perhaps she exists in other possible worlds. I demonstrate how the mathematical logic of possible worlds is necessary to move beyond the impasse of Some Thing Black to construct what is finally a more satisfying formal response to her death in The Plurality of Worlds of Lewis. In the process, I show how Roubaud’s emphasis on potentiality reveals important consequences for the way we understand the work of literature in relation to that of science and mathematics.