Gabrielle ?milie Le Tonnelier de Breteuil, marquise du Ch璽telet (December 17, 1706 - September 10, 1749) was a French mathematician, physicist, and author during the Age of Enlightenment. Her education has been the subject of much speculation, but nothing is known with certainty. Her father brought tutors to the house for her and by the age of twelve she was fluent in Latin, Italian, Greek and German. She also received education in mathematics, literature, and science. She had an arranged marriage in 1725 to the Marquis Florent-Claude du Chastelle. In 1733 she resumed her mathematical studies. In 1737 she published a paper entitled Dissertation sur la nature et la propagation du feu, based upon her research into the science of fire, that predicted what is today known as infrared radiation and the nature of light. Her crowning achievement is considered to be her translation and commentary on Isaac Newton's work Principia Mathematica. The translation, published after her death in 1759, is still considered the standard French translation. Voltaire, one of her lovers, declared in a letter to his friend King Frederick II of Prussia that du Ch璽telet was "a great man whose only fault was being a woman". She died in 1748 from a pulmonary embolism, at the age of 42.