Tolstoy's most cogent and focused statement on aesthetics, the 1896 treatise What is Art?, answers the question posed by its title with the blunt statement that “art is infection.” This paper observes that a consistent system of metaphors of infection is central not just to What is Art?, but to every stage and genre of Tolstoy's writing–polemical, autobiographical, and literary works, early journals and late-life rantings. Arguing that the complex of disease metaphors running through the entirety of Tolstoy's work affords the reader one way of conceptualizing Tolstoy's massive oeuvre as a single coherent corpus, the essay reads specific moments from a range of Tolstoyan texts in order to sketch out infection's relation to the themes of mortality, morality, and the artistic imagination that loom most largely in Tolstoy's thought. Reexamined in this light, the apparently strained relationship between the aesthetic and ethical aspects of Tolstoy's artistic theory turns out to be more nuanced, compelling, and more resonant with the Kantian aesthetic tradition than previously recognized.