Gabrielle Emilie le Tonnelier de Breteuil was born in Paris in 1706 AD to a well-connected, noble family – her father the baron was a favorite of Louis XIV – and had every privilege a little girl could want. Little is known of her early education (it was likely whatever was appropriate for girls at the time), but when she was 18, the baron arranged for his only daughter to marry into one of the oldest bloodlines in Lorraine. The Marquis du Chatelet brought prestige… but little else. For the first years of her marriage, the new marquise lived a very traditional life: managed the household in Semur, bore a daughter and two sons, and when appropriate enjoyed all the pleasures of Paris.
It was in 1733, when she was again in Semur pregnant with her second son, that Emilie became interested in mathematics. The marquise took up the serious study of Descartes’ analytical geometry, and began translating Newton’s new 'Principia,' adding her own commentary including completion and expansion of some of the Brit’s key hypotheses. Upon publication, the latter became the definitive edition across Europe.
Through the rest of the 1730s and 1740s, she continued to read, study, and write, even while caring for her husband, children, and several lovers. Indeed, her writings on optics, grammar, and a critical commentary on the Old and New Testaments were almost as famous as her scandalous affairs. Among those, Voltaire – who wrote to Frederick II of Prussia that she was “a great man whose only fault was being a woman” – and the mathematician de Maupertuis and the philosopher de la Mettrie. Her last lover, the soldier-poet de Saint-Lambert, was father to her last child; Emilie du Chatelet died in 1749 a week after giving birth.