Physiological, political, and poetic studies of the relationship between the human body and voice saw increased attention and took on new significance in British literature of the politically turbulent period between the 1770s and the 1820s. Focusing on Erasmus Darwin, John Thelwall, and Percy Bysshe Shelley, three writers whose works draw together the fields of science, politics, language, and literature, and who were subject to charges of political radicalism and materialist philosophy, Alice Rhodes draws attention to a developing theory of spoken and poetic utterance which, for its subscribers, suggested a fundamental, material, and reciprocal connection between the speaking body and the physical, social, and political worlds around it. By investigating the Romantic-era fascination with the mechanics and physiology of speech production, she explores how Darwin, Thelwall, and Shelley came to present the voice as a form of physical, autonomous, and effective political action.