Just like the kings of France, France’s greatest philosophers had their mistresses too. But unlike the mistresses of kings, like Madame de Pompadour or Madame de Montespan, who found their way into the history books, most philosophers’ mistresses stayed anonymous. Today I want to talk about the exception, the mistress of the greatest French philosopher of the 18th century, a woman who made it into the history books not just because of him, but because of her own remarkable personality and sharp mind.
So Who Was the Marquise du Châtelet?
Her name was Gabrielle Émilie Le Tonnelier de Breteuil (1706-1749). She was born into the family of the barons de Breteuil, whose château I wrote about before, and from childhood she was known for her sharp mind. By age 12 she already knew Latin and Italian, could play the harpsichord and sing. At 15 she began translating the Aeneid, by the Roman poet Virgil, into French (in verse).
Soon after, she decided none of this was quite enough, so she added English to the list of languages she had mastered and began studying mathematics with Maupertuis (1698-1759), considered one of the greatest philosophers of his time and later known as Voltaire’s rival. And finally, I can’t skip the important essay she wrote on happiness.
At 19, she married the marquis du Châtelet, who was 11 years older than her, and from then on she was known as the marquise du Châtelet (the marquis served as governor of the town of Semur-en-Auxois in Burgundy, where she lived during the early years of her marriage). The couple had three children, but conveniently, her husband, an officer in the king’s army, spent most of his time away, which left her plenty of time to take a few lovers of her own. The most famous of them was the duc de Richelieu (1696-1788), without question the greatest lover in 18th-century France, who gave even Casanova a run for his money.
The Affair with Voltaire
In 1733, Émilie met the man whose name would be linked to hers forever, the famous French philosopher François-Marie Arouet, known as Voltaire (1694-1778). They met at a dinner and found themselves talking about Latin poetry, mathematics and astronomy. The marquise’s “geek chic” was so strong that Voltaire fell for her instantly, even though according to Madame du Deffand (1697-1780) she had “a tiny head, a flat chest, huge hands, a pointed nose and skin like pumice stone.”
The marquise and Voltaire became one of the dazzling couples of the 18th century, and when they weren’t in bed together, they studied mathematics and Newton’s physics side by side. “God, how delightful it is to be in your arms, what happiness it is to be able to be with the one I love,” Voltaire wrote to his beloved in 1734. That same year, the two moved to the Château de Cirey, in northeastern France. In this isolated château, the two of them studied the sciences together, and Voltaire spent no small amount of time writing several of his books.
During this period, the marquise’s husband joined the couple, but he was careful not to intrude on them too much, living in a separate apartment and eating at separate hours. All of France was stunned, not because the marquis was willing to live with his wife’s lover under one roof, but because the lovers had stayed faithful to each other for so long.
The idyll between Voltaire and the marquise lasted until 1747. Voltaire, who was 53 and quite the hypochondriac, stopped satisfying his beloved sexually, worried about his health. That year, the marquise met Captain Jean François de Saint-Lambert (1716-1803), who was ten years younger than her, and the affair between them began to bloom.
In October of that year, Voltaire caught the two of them in a rather embarrassing situation, and after some back and forth, challenged Saint-Lambert to a duel at dawn. Madame du Châtelet, alarmed at the thought that one of her lovers might kill the other, came to Voltaire at two in the morning and declared her eternal love for him.
But on that occasion, she reminded him that he himself had told her his powers were failing him, so he had no reason to be offended that his friend was standing in for him there, since that effort could only have put his own health at risk. Voltaire accepted this philosophical argument. The next day the two lovers made peace, and Voltaire told Saint-Lambert, “I’ve forgotten everything that happened. I was wrong to be jealous of you. You’re at the age when a man can enjoy love and passion. Enjoy them while you can, because time passes so quickly…”
The Bitter End of a Love Triangle
And so began a love triangle between the marquise, Voltaire and Saint-Lambert, and the three of them moved between Paris, Cirey and the Château de Lunéville in Lorraine, where they were hosted by the duke of Lorraine, Stanislas Leszczynski (1677-1766), father of the queen of France. At this château, the marquise discovered she was pregnant by Saint-Lambert. To disguise the father’s identity, the marquise, Voltaire and Saint-Lambert traveled to the Château de Cirey and invited Émilie’s husband to join them.
The marquis didn’t mind much about the romantic triangle woven between his wife and her two lovers, and he happily played the part assigned to him. After dinner, the husband dutifully climbed into the marquise’s bed, granting a kind of “seal of approval” to the baby who would be born (Voltaire, witty as ever, argued the child should be filed under “Miscellaneous” in the catalogue of Madame du Châtelet’s works).
But the love triangle formed in 1747 ended tragically in September 1749. That month, the marquise gave birth to a baby girl, who died shortly after. At 43 years old, and since the birth had not been easy, her body couldn’t hold on, and six days later Madame du Châtelet died. Voltaire, stunned with grief, walked out of the marquise’s room and collapsed.
It was Saint-Lambert who managed to bring him back to himself somewhat, and Voltaire turned to him in rebuke and said, “You’re the one who killed her. What were you thinking when you decided to get her pregnant?” Voltaire asked for the marquise’s ring, which he believed held his portrait, as a keepsake, but when he received it, he discovered it held Saint-Lambert’s portrait instead. To this, Voltaire said, “That’s how women are! I took the duc de Richelieu out of the ring, and now Saint-Lambert has taken me out. That’s how the world works…”
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