This article advances a fresh understanding of the ethics and aesthetics that defined George Eliot's fictional maturity, particularly in light of Eliot's fascination with energy science. Victorian scientists discovered that the energy of the world was ineluctably lost or “diffused,” never again to perform productive work. But many mid-Victorians saw diffusion in optimistic terms, in contrast to more disconsolate perspectives at the century's close. In Middlemarch (1873-74), I argue, Eliot utilized the theory of energy diffusion as a model of eternal fulfillment. She did so in two ways. First, energy science provided a heuristic for Eliot's sympathetic vision. While her protagonists reflect the breakdown of interpersonal bonds—the impossibility of any perfect recognition of another's pain—the novel deploys the terms and tropes of diffusion to suggest sympathy's post-subjective effects in the lives of others. Second, I submit that energy science shaped Eliot's distinctive understanding of the novel itself as a mode of cultural production. Through figurations of unproductive energy, Eliot came to imagine how wasteful, prodigal acts of reading could bring about an ethically revitalized world. Energy science thus enabled Eliot to reconcile conventional claims about the social purpose of the novel with incipiently Arnoldian canons of art's autonomy from politics. By reading Eliot's work alongside the work of contemporary scientists, I disclose a radical ideal of literature's unproductive powers, one that linked new ideologies of formal appreciation with the novel's longstanding social promise.