I analyse Shelley’s fraught relationship with Byron’s self-monumentalising, flippantly self-mocking poetics and personal pride, arguing that Shelley’s notion of a ‘Promethean’ poet who catches the strains of general human ‘sympathy’ tenses productively against what he saw as Byron’s narrow drive to create an elevated poetic ‘self’. Shelley, though he admired Byron’s poetics in many ways, also saw his friend as being at risk, poetically and personally, of the sort of inflexible remove that the Promethean poet might fall into if their overreaching ambition comes to render them ‘cold’ and removed from their historical moment. Though acts of intertextual intimacy with Byron’s work, Shelley explores various forms of ‘coldness’: some Byronic laments for the trials of human mutability, some distinctively Shelleyan forms of ‘coldness’ that strive to regenerate, through defamiliarisation, the very ‘ashes and sparks’ of creativity that the poet, with their largely unavoidable removal from the world, risks disdaining.

This chapter investigates how Percy Shelley’s poetry of speech draws on a Darwinian materialist understanding of the body and can be read alongside John Thelwall’s theory of rhythmus in its figuring of speech as unstoppable action. Focussing on Shelley’s later works, including A Defence of Poetry, Julian and Maddalo, Prometheus Unbound, and The Mask of Anarchy, this chapter draws out the ways that materialist and embodied models of speech production underpin Shelley’s figuring of poetry as a force of change, and allow him to blur the boundaries between art and science, aesthetics and politics, the internal and the external. It examines how such understandings of the communicative power of voice as a physical and material force that can be felt as action or movement challenge the notion that Shelley’s later poems are indicative of the failure of both poetry as a means of communication and utterance as a means of effecting change.