Two books about her have been published this year, numerous book reviews have hailed her role in the Enlightenment, and an op-ed in the Financial Times today extolled her accomplishments. This week marks the 300th anniversary of the birth of Marquise du ChÃ¢telet, Gabrielle Ã‰milie le Tonnelier de Breteuil. A Parisian aristocrat — in our times most famous for being the mistress of Voltaire — du ChÃ¢telet to this point has almost been forgotten for her own contributions to the intellectual and scientific life of the Age of the Enlightenment in Europe. Educated by tutors, she delved deeply into the sciences — most notably physics and mathematics. Du ChÃ¢telet translated Isaac Newton's Principia Mathematica and included her own commentary. In her own text, Institutions de physiques, she elaborated on Leibnitz's ideas. Her work on conservation of energy provided critical insights that led to Einstein's E=MC² equation. The Marquise also was interested in moral philosophy, metaphysics, and political theory and collaborated with Voltaire during their years at the Chateau de Cirey. She had three children with her husband, had several other lovers besides Voltaire, and died after childbirth in her early forties. An amazing person.