This book shows how, in his enormously influential (1689), John Locke embraces the new rhetoric of seventeenth-century natural philosophy, adopting the strategies of his scientific contemporaries to create a highly original natural history of the human mind. With the help of Locke's notebooks, letters, and journals, Peter Walmsley reconstructs Locke's scientific career, including his early work with the chemist Robert Boyle and the physician Thomas Sydenham. He demonstrates too how the Essay embodies in its form and language many of the preoccupations of the science of its day, from the emerging discourses of experimentation and empirical taxonomy to developments in embryology and the history of trades. Widely research and lucidly and engagingly written, constitutes an important new reading of Locke, on that shows both his brilliance as a writer and his originality in turning to science to effect a radical re-invention of the study of the mind.