This essay explores the philosophy and poetry of the nervous system in Erasmus Darwin's late 18th-century science of life, arguing that Darwin's theory of animation constitutes an unrecognized chapter in the history of what is now called "biosemiotics." I show how Darwin's earlier modern approach to epigenesis and plasticity-concepts resurgent not only in present day developmental biology and neuroscience, but also in continental theory and philosophychallenges these present discourses to grasp mimesis, poiesis, and rhetoric as intrinsic to the logic of life and to any possible science of the biological sign. Uncovering this possibility means displacing Catherine Malabou's influential neo-Kantian approach to plasticity, which, like that of Kant himself, works to suppress the natural histories of meaning that epigenesis opened in the late 18th, as well as the late 20th, centuries. From the alternative, materialist perspective opened in Erasmus Darwin's work, rhetoric and poetics are implicated in the historical and actual conceptualization of epigenetic plasticity and biosemiosis not because biology is a fictive discourse, but because neural formation and communication actually comprise processes of transposition, association, double-meaning, part-for-whole substitution, and species-specific distortion for which metaphor, metonymy, allegory, synecdoche, and (anthropo-)morphism are technically correct and illuminating names. From this perspective, the most baffling and notorious feature of Erasmus Darwin's own use of words can also be conceived anew. His