The inimitable Nancy Mitford’s account of Voltaire’s fifteen-year relationship with the Marquise du Châtelet—the renowned mathematician who introduced Isaac Newton’s revolutionary new physics to France—is a spirited romp in the company of two extraordinary individuals as well as an erudite and gossipy guide to French high society during the Enlightenment. Mitford’s story is as delicious as it is complicated. The marquise was in love with another mathematician, Maupertuis, while she had an unexpected rival for Voltaire’s affections in the future Frederick the Great of Prussia (and later in the philosophe’s own niece). There was, at least, no jealous husband to contend with: the Marquis du Châtelet, Mitford assures us, behaved perfectly. The beau monde of Paris was, however, distraught at the idea of the lovers’ brilliant conversation going to waste on the windswept hills of Champagne, site of the Château de Cirey, where experimental laboratories, a darkroom, and a library of more than twenty-one thousand volumes enabled them to pursue their amours philosophiques. From time to time the threat of impending arrest would send Voltaire scurrying across the border into Holland, but his irrepressible charm—and the interventions of powerful friends—always made it possible for him resume his studies with the cherished marquise.