Du Châtelet had a 15-year affair with Francois Marie Arouet de Voltaire. Voltaire recognised her talents. Châtelet helped Voltaire write his book, "Elements of Newton’s Philosophy". She had an unwanted child with Jean François de Saint-Lambert when she was 42. She translated "Principia Mathematica" by Isaac Newton into French while she was pregnant. She died from an infection six days after giving birth to her daughter. It was 1749.