New resources have led to new insights into the history of English vocabulary. The appearance of machine-readable corpora has made it possible to contextualise particular idiolectal usages much more comprehensively than was possible until recently. Such developments have allowed, through the harnessing of the large bodies of data to be found in the Oxford English Dictionary and other resources, a much better understanding of intertextual engagement: what might be called authorial invention, the focus of this chapter. The chapter focuses on authorial invention during the Romantic period, with reference to three writers whose imaginative outputs drew profoundly on their understanding of medicine: Samuel Taylor Coleridge (1772–1834), Mary Shelley (1797–1851), and John Keats (1795–1821). As Richard Holmes has argued, Romanticism drew profoundly on its scientific inheritance, in the cases analysed here derived from direct or indirect encounters with thinkers such as Thomas Beddoes (1760–1808), Astley Cooper (1768–1841), William Cullen (1710–1790), and Erasmus Darwin (1731–1802). However, they transformed this inheritance through what Holmes terms ‘imaginative intensity’.