Who knew that one of mankind’s greatest scientists also worked as a gumshoe on London’s mean streets, or that this same absent-minded professor helped England fix its monetary policy from an office in the Tower of London? Thomas Levenson brings all sorts of surprises to light in his own sleuthing of a little known but significant episode in British history involving Sir Isaac Newton -- subject of his recent book, Newton and the Counterfeiter: The Unknown Detective Career of the World's Greatest Scientist.

Levenson stumbled onto his story while working on a larger history of science: He read a letter in Newton’s files from a “human voice in desperation:” William Chaloner, stuck in Newgate Jail in 1699, facing the gallows for treason (counterfeiting). Levenson was unable to link together this unlikely pair for a decade, until he struck gold in a stash of 400 documents signed by Newton while he served as a civil servant in the British Mint.

The tale Levenson pieced together follows Chaloner from his rural origins to a cunning criminal career in plague-stricken 17th century London, as well as Newton’s passage from world-renowned natural philosopher in isolated Cambridge University, to a promised sinecure in the Royal Mint. The tale of their intertwined fates illuminates a time when science was beginning to make its mark not just on the intelligentsia, but on all of society. Levenson describes how the scientific revolution meant “a much broader change in thinking,” new ways of problem-solving that gave even common people a leg up.

Newton entered his second career in London to find the English currency in a state of crisis: rampant counterfeiting, as well as the loss of silver from existing currency. One of the geniuses behind this state of affairs was Chaloner, who had come to “coining” by way of such money-making schemes as pornographic watches. Levenson describes “Newton’s mind at work” as he builds chains of evidence and pursues his prey with elaborate traps, including informants and double agents placed in counterfeiting gangs.

Levenson finds “evidence of Newton’s ruthlessness,” as he brings Chaloner to the gibbet with a case that “was rhetorical and persuasive more than precisely accurate.” In their calculation and drive, both men somehow captured the new scientific spirit of the times. Says Levenson, “When big ideas happen, they don’t just happen in own spheres. There’s an effect that spreads well beyond them. And if they matter to the way people lead their lives, then people will find out about them and do things with them...”