On this date in 1706, Gabrielle Emilie le Tonnelier de Breteuil, later known as the Marquise du Chatelet, was born in Paris. The daughter of the Baron de Breteuil, she showed great aptitude and was given broad latitude to study. Emilie was translating Virgil by age16. She married Marquis Florent du Chastellet in 1725 at the age of 19. He was governor of Semur-en-Auxois and later took on a military career. They had three children before essentially parting ways, although Emilie resisted any idea of divorce. Living a social life in Paris, Emilie met Voltaire, with whom she lived for her remaining life. It was Voltaire who changed her name to "Chatelet." When Voltaire was facing arrest, they went to live together at her husband's family estates at Cirey, where both of them spent some of their most productive years of work, and were known for working day and night. Emilie wrote treatises on mathematics, physics and philosophy. She is best-known in France for translating Newton's Principia, which, as the only French translation of that work, was reprinted in 1966. The Marquise reportedly fell in love at the end of her life with Marquis de Saint-Lambert and became pregnant by him. Voltaire was said to have entered into the campaign to persuade her husband that he was the father. She gave birth to a daughter on Sept. 10, 1749. Emilie died six days later, at the age of 43, and her daughter died soon after. Emilie had dedicated her Deistic manuscript, Doubts about Revealed Religion, which was posthumously published in 1792, to her companion, Voltaire. D. 1749.