Lessons from John Graunt.

Correspondence to: Dr K J Rothman, Epidemiology, 1 Newton Executive Park, Newton Lower Falls, MA 02161, USA John Graunt, 17th century citizen of London, thought of himself as a haberdasher. History knows him, however, as the first epidemiologist and demographer. He made his mark because he grasped the potential in an overlooked data source of his day-the weekly Bills of Mortality-and he mined this resource admirably in his only scientific work. His book, published 333 years ago, was a slim edition with a donnish title: Natural and political observations mentioned in a following index, and made upon the Bills of Mortality. 1