The life of Isaac Newton (1642–1727) is hardly unknown. Reclusive though Newton may have been in the prime of his invention, long before the end of his life he had become a moving tourist attraction. French abbés, German academic tyros and Italian astronomers considered a visit to Newton to be worth the detour, whether they were seeking interpretations of ancient history, demonstrations of alchemical furnaces, or guidance on mathematical analysis. As President of the Royal Society from 1703, Newton took control of a body at least part of whose purpose was international communication and used it shamelessly to promulgate his own version of his past. Thanks to his careful supervision of both evidence and the forms of inquiry, the committee of the Royal Society that was charged with determining who had been the first mathematician to discover the calculus came down firmly on Newton’s side. From then on, the myth of Newton’s youthful genius began to acquire more and more lustre. It was burnished enthusiastically by a succession of star-struck admirers, whose accounts of their hero were drawn together by a calculating nephew-in-law, with an eye to supplementing his considerable inheritance through a biography of, and posthumous publications of writings by, the great man. Poetry, paintings, portrait medals and a memorial in Westminster Abbey followed the scientist’s death in what the art historian Francis Haskell referred to as ‘the apotheosis of Newton’. Yet always there was a darker undertow.

The authors of well-meaning English instructions for youth discovered that the tales of Newton’s chamber-fellows or secretaries, revealing absent-mindedness and obsession, could easily be drawn into the penumbra of eccentricity that surrounds genius. Newton’s Continental biographers were less charitable. The nineteenth-century mathematician Augustus de Morgan worried instead about what he