Gabrielle Émilie Le Tonnelier de Breteuil, the Marquise Du Châtelet, was for a long time best known as the lover and companion of Voltaire. But the “divine Émilie,” as he called her, was a brilliant figure of the Enlightenment in her own right. And totally sounds like somebody you’d like to meet.

It’s true that Émilie Du Châtelet was married to someone else during her 15-year long relationship with Voltaire, but her husband is said not to have minded. She and Voltaire collaborated on his book about the elements of Newton’s philosophy, which was radical stuff for a France still enamored with Rene Descartes, but she also published her work and was highly regarded for it. Her Institutions de physique (1740) and translations of Leibniz’s metaphysics impressed even the crustiest academicians. She was, however, barred from all but the public sessions of the Academie des Sciences because of her gender.

Judith P. Zinsser reveals all this and more in her detailing of Du Châtelet’s translation of Isaac Newton’s monumental Principia into French in the 1740s. The Marquise’s work is still considered the standard French translation.

Newton’s masterwork had been written in Latin—the universal language for so long in Europe—and first published in 1687. The third edition of 1726 was the occasion of the work’s first major translation, into Newton’s native English. Du Châtelet did much more than just give a verbatim translation of Newton, however. She explained him.

An autodidact in an age when there was no formal education for women, she was one of the few people, male or female, who understood calculus. So it was actually her commentary on Newton that had the most effect: “Du Châtelet offered three different ways to access Newton’s celestial mechanics. Each builds on the other in terms of the detail given and the complexity of the mathematics required of the reader.”

It’s an understatement to say she introduced Newtonian mechanics to the French-speaking world: she ushered it in, made it welcome, made sure everyone could understand it, and updated it with more recent discoveries (Newton had died in 1727). Such efforts are sometimes as vital as actual discoveries themselves.

It still took until nearly the end of the 18th century before Newton’s theories were universally accepted on the continent. The Marquise was one of the key transmitters of that transformation. In a contemporary review, it was said she “offers us Newton made accessible to everyone.”