Émilie du Châtelet

For October’s posts we decided that instead of a particular theme, to celebrate 1 year of having the blog we would do an author’s choice which means this month it is going to be a mix of themes. This month I get to go first and even though my list of women that I want to look into might be longer than War and Peace I thought who better to go with then someone that shares your name?

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Émilie du Châtelet was a French mathematician and a famed lover of the controversial playwright Voltaire. Her scientific work includes what is still considered the definitive French translation of Newton’s Principia. Yet after her death, Émilie was all but forgotten, and if she was remembered at all, her achievements were often belittled, lost in the shadow of the “great men” in her life. However, modern-day historians have rediscovered Émilie, and her story is inspiring new generations of female mathematicians and this lost history is something that stood out to me.

Émilie du Châtelet - Wikipedia
Émilie du Châtelet. Image from Wikipedia

Gabrielle Émilie le Tonnelier de Breteuil was born in Paris on December 17th, 1706 as the only daughter of 6 children. Her father was Louis Nicolas le Tonnelier de Breteuil, who was a high ranking official of the court of Louis XIV. As part of French aristocratic society, Émilie’s family entertained often and distinguished scientists and mathematicians were frequent visitors to the household. As a young woman she learned to speak 6 languages and was educated in maths and science alongside her other studies, and perhaps a little ahead of his time her father recognised her talents and ambition making an effort to introduce her to his scientific visitors as well as arranging for Bernard de Fontenelle to visit and talk about astronomy with her when she was 10 years old.

There is some debate as to whether Émilie’s mother, Gabrielle-Anne de Froulay approved of her husband’s interest in their daughter’s education. Gabrielle-Anne had been raised in a convent which at the time was the predominant educational institution available to French girls and women. And while some sources report that her mother did not approve of her intelligent daughter, or of her husband’s encouragement of Émilie’s intellectual curiosity, there are also other indications that her mother not only approved of Émilie’s early education, but actually encouraged her to vigorously question stated fact. Amongst her other intellectual education, her father also arranged training for her in physical activities such as fencing and riding. Émilie also liked to dance, was a passable performer on the harpsichord, sang opera, and was an amateur actress. As a teenager, short of money for more books (we’ve all been there), she used her mathematical skills to devise highly successful strategies for gambling.

On 12 June 1725, she married the Marquis Florent-Claude du Châtelet-Lomont. Her marriage conferred the title of Marquise du Châtelet. Like many marriages among the nobility at the time, theirs was arranged. As a wedding gift, her husband was made governor of Semur-en-Auxois in Burgundy by his father, and the recently married couple moved there at the end of September 1725. At the time of their marriage Émilie was nineteen years old and her husband was thirty-four. Together the couple would have three children: Françoise Gabriel Pauline, Louis Marie Florent, and Victor-Esprit, sadly Victor-Esprit died as a toddler in late summer 1734.

In 1733, at the age of 26, she captivated Voltaire, he was seduced by her brains as well as her beauty. Voltaire was already a notorious upstart commoner with a wicked wit, Émilie, by contrast, was born to the aristocratic life and a polar opposite to him. Having “done their duty” for the Châtelet line, Émilie and her husband lived relatively separate lives, not an uncommon situation in aristocratic families. Less common however, was the remarkable friendship that developed between husband and wife. The marquis supported not only Émilie’s unusual ambition, but also her passionate relationship with Voltaire. Taking a lover was quite normal at that time, especially owing to the arranged marriages, but Émilie and Voltaire scandalised polite society when they set up house together (extramarital love affairs were supposed to be discreet dalliances, not alternative marriages). Critics of Émilie held the opinion that she was too ambitious, too intellectual, too emotional and too sexually liberated. Too much of a feminist, too. She was passionate about her education and pulled no punches when she wrote about the struggles she went through to educate herself in higher mathematics and physics, even writing-

 “If I were king, I would reform an abuse which effectively cuts back half of humanity. I would have women participate in all human rights, and above all, those of the mind.”

Portrait of Émilie du Châtelet, by Nicolas de Largillière c. 1740. (Louvre)

Both Voltaire and Émilie would team together to help to promote Newton’s ideas on physics against those of the accepted Cartesian physics. As mathematics was crucial to Newton’s approach Voltaire would need Émilie’s help. However, disaster struck in April 1734 when Voltaire’s French publisher released his Lettres Philosophiques without his permission. These letters criticized established religions and political institutions and an arrest warrant was issued and Voltaire went into hiding. Émilie raged to her friends that France’s treatment of its greatest writer was unjust. Her appeals to the authorities, as well as those of her husband and other aristocratic friends meant that Voltaire was allowed to return to France, where he lived under a kind of house arrest at the Châtelets’ run-down château at Cirey, in Champagne. 

Émilie moved to Cirey to live with Voltaire and of course tongues wagged, but the couple set about turning Cirey into an informal academy where they studied, wrote, discussed philosophy and hosted free-thinking intellectuals. Émilie would take the couple’s project even further in a 180-page “commentary” that she added to her translation of Newton’s Principia. This included a relatively accessible reader’s guide to the main arguments in Newton’s gravitational theory of planetary motion, and her appendix also included her own reworking of some of the Principia’s key proofs in the language of  calculus. While this project was impressive, her fame among European intellectuals came not from her translation of the Principia but from an earlier work of popular science – called Institutions de Physique (Fundamentals of Physics) – in which she bravely attempted to integrate the work of Newton and Leibniz.

Unfortunately,  Émilie’s story doesn’t end with a happily ever after. In May 1748, she began an affair with the poet Jean François de Saint-Lambert and became pregnant and in a letter to a friend, she confided her fears that she would not survive her pregnancy. On the night of 3 September 1749, she gave birth to a daughter, Stanislas-Adélaïde, but died a week later, at Lunéville, from a pulmonary embolism, at the age of 42. Her daughter also died in Lunéville on 6 May 1751.

Society gossips believed she’d got what she deserved for living so outrageously, so freely. Voltaire had stayed with her until the end and thought they were no longer lovers, he had remained “a tiny planet in her vortex, hobbling along in her orbit”, as he wrote in a letter to a friend.

Émilie had hoped her work on Newton would live forever. But soon after her death, her scientific reputation faded, too. Voltaire lost interest in science, and her Principia languished in a drawer. She had worked 18 hour days during her pregnancy in an attempt to finish it before she gave birth but this work wouldn’t languish in a draw forever as Alexis Claude Clairaut, a French mathematician and astrologer found her work. He had checked her calculus proofs in the months before she died, and he’d refined Newton and Halley’s calculations to obtain the accurate prediction of the return of Halley’s comet in 1759. What better celebration than to publish Émilie’s book in the same year, after all she’d known the comet held a key to securing Newton’s reputation.

While the ending of Émilie’s story is tragic she should be remembered for the amazing mathematician that she was. Far from your ordinary French aristocrat she strived to learn more and allow others to do the same.

Author– Emily Casson






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