Emilie du Chatelet was one of the greatest thinkers of the 18th century, a woman whose work was of vital use to Einstein and who, until now, has been largely ignored by history. Fiercely intellectual and passionate, Emilie's relationship with Voltaire was as radical as her thinking; only after swordfights, wild affairs and rigging the French national lottery did the two finally find love together. In an isolated chateau they combined their unique talents, producing theories more than a century ahead of their time. Together they challenged the social norms and great injustices of the era, as well as expanding on Newton's Laws. When they ran out of money, Emilie, with her razor-sharp mathematics, would gamble in Versailles. Their progressive thinking won them only public scorn and even imprisonment in the Bastille for Voltaire. When their love finally ended, Emilie found happiness in an independent life until, tragically, she became pregnant. Then in her forties, it meant an almost-certain death in childbirth. Voltaire returned to comfort her in her last months, when she wrote some of her most important work.

David Bodanis lectured at the University of Oxford for many years. Originally from Chicago, he now lives in London.