The manuscript by Sydenham quoted on p. 10 is from Kenneth Dewhurst, John Locke, Physician and Philosopher: A Medical Biography (Wellcome Historical Medical Library, 1963). Henry Ireton’s question to the Leveller leaders in the Putney debates quoted on p. 43 is taken from A. S. P. Woodhouse (ed.), Puritanism and Liberty (J. M. Dent & Son, 1938). Coleridge’s comment cited on p. 97 comes from Kathleen Coburn (ed.), The Notebooks of Samuel Taylor Coleridge, ii. 1804–1808 (New York, 1961), entry 2627.