Émilie du Châtelet, like de Beauvoir, has suffered somewhat in reputation by being in the shadow of a more famous boyfriend—in this case, Voltaire. A brilliant scientist in her own right, she is best known for her translation and commentary of Isaac Newton’s Principia Mathematica into French, which remains the standard text there today. This commentary laid the foundational mathematics for the modern concept of kinetic energy. She also predicted the existence of infrared radiation.

I first meet her at a party at my place, where she turns up with several other faces from the French contingent. The next time our paths cross, she introduces me to Albert Einstein. She appears regularly throughout the narrative, often with de Beauvoir, and like her, brings a welcome female perspective to the events that unfold.