I first became interested in Gabrielle-Émilie le Tonnelier de Breteuil, Marquise du Châtelet, while I was living and working in the Château de Breteuil many years ago, and I happened to ask the present Marquise de Breteuil, “Who is the beautiful woman in that painting?” I discovered that Émilie was a married gentlewoman of high rank, famous in France for her remarkable knowledge of physics and for her illicit affair with Voltaire, philosopher, playwright and poet, who was twice imprisoned in the Bastille for flouting the government of France.

The novel evokes four adventurous years during which Émilie managed a personal revolution: in the way she lived, the way she worked, and the way she was known to the world. She battled to save Voltaire from prison, made her country château a bastion of free thought, created her own laboratory, and began her translation into French of Isaac Newton’s Principia Mathematica, a contribution to physics that has never been superseded.

Passionate, ambitious and headstrong, Émilie craved the absolute. Voltaire said: “What Émilie sees, she wants. And she has a very good eye.” The man she wanted was Voltaire. They were both writers, yet the key to their love affair is not to be found in their letters to each other, for those letters vanished in 1749. Instead I offer a new key: Émilie’s ‘voice’, as she tells her own story.

It begins in April 1734 when a warrant for Voltaire’s arrest is issued in the name of the king. From the Château of Montjeu in Burgundy, Émilie persuades Voltaire to go into hiding at Cirey, a tumbledown castle in the Champagne countryside, while she returns to Versailles to argue for him at court. Voltaire is ready to use his wealth to create a haven at Cirey, but only if Émilie will join him. Tempted back to Paris, they face some crucial questions. Emilie is married to the Marquis du Châtelet: can she defy royal and religious authority to live with Voltaire, or is this a dangerous dream bound for disaster? If they seek refuge together, how will she find ways to keep her unpredictable lover out of prison while pursuing her own work?

I created The Propagation of Fire out of dramatic, true events in the life of a real woman who sought to shape her own destiny. I see her as a model of courage for the women of any age. Three centuries ago, in a time and a country where rights for women scarcely existed, she chose an authentic life directed by her great intellect and her magnificent passions. In this, she both belongs to our times and surpasses them.

Most of my research was in French, and a delightful portion of it was in France. For some of my discoveries, click below.