In order to promote new forms of thinking about posthumanism, my research paper would like to focus on the extent to which John Keats’s theories of artistic creation seem to point beyond traditionally (European-centred) Romantic traditions. In particular, my paper aims to combine ecocritical explorations of Keatsian ecosystems (Bate 2000; Scott 2014; Clark 2015; Henning 2018) with new materialist approaches that foreground the interconnectedness of the various (human as well as nonhuman) entities inhabiting ecosystems. In particular, this paper would like to explore the potentiality that Keats’s ideas on poetic receptivity and creation may have for an aesthetic theory that goes beyond human exceptionalism. Relying on recent studies on the importance of Keats’s medical background (de Almeida 1991; Roe 2017), Keatsian receptivity and his notions of ‘negative capability’ and ‘material sublime’ will be placed in the context of medical and materially-oriented discussions of heightened sensibility and expanded sympathy, which emphasise the intersubjective orientation of the nervous system (Bassiri 2013). For Keats, the creative process is inseparable from the enhancement of sympathy: the chameleon-like poet “is continually in for and filling some other body” (Letters, 210) in a yearning that is not just expressive of the might of human mental powers, but rather strives for the dissolution of the boundaries of the self so as to promote the identification with human as well as nonhuman and even inanimate entities (for example a sparrow, or a billiard ball). By so doing, Keats’s aesthetic theory rejects the notion of “the Wordsworthian, egotistical sublime” (Letters, 210) and embraces instead the conception of environmental relations founded on interdependency and mutual shaping, in ways that seem to anticipate ecocritical notions of ‘transcorporeality’ and ‘intra-activity’ (Alaimo 2010) among human and nonhuman beings, and their collective constitution of the world. While in Keats’s aesthetic theory and poetry the dissolution of individual boundaries is never far from the risks of pathology, his ideas about receptivity contribute in significant ways to the de-essentialist perspective that is crucial to any discussion of posthumanism. By focusing on extracts from Keats’s letters dealing with his theory of poetic receptivity and creation and on the environmental intersubjective relations to be found in his poetry (the Odes but also some of his narrative poems), this paper intends to argue for the relevance of Keats’s works for the de-centering of the self that preludes to new possibilities for the human and post-human.