Noble Blood - The Mind of Émilie du Châtelet (Part 1)

Episode Date: May 5, 2026

History has often reduced the brilliant mathematician and physicist Émilie du Châtelet to her relationship with a famous man (Voltaire). But she was a fascinating figure in her own right, an 18th century polymath at the forefront of conversations about how the world worked. Support Noble Blood:—PRE-ORDER 'THE ARCANE ARTS'— Bonus episodes, stickers, and scripts on Patreon— Order Dana's book, 'Anatomy: A Love Story' and its sequel 'Immortality: A Love Story'  See omnystudio.com/listener for privacy information.

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Every family has its secrets. But what happens when you discover that your dad has been living a double life? That is not the look of an innocent man. Is everyone lying to me about who they are? I felt such desperation. I felt it was what I had to do. Listen to Deep Cover the Family Man on the IHeart Radio app Apple Podcasts, or wherever you get your podcasts.

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Listener discretion advised. Circa 1745, the rising French painter Marianne Loire received a commission. A portrait of a noblewoman was not an unusual assignment, but her sitter was an unusual noblewoman. In the finished portrait, Marianne's subject is seated in an ornate chair with the perfect posture expected from one of her noble class. She wears a loose-fitting robe al-anglis in a deep blue, lined with fur on the bodice and lace on the sleeves. A diamond brooch is pinned to the ribbon around her throat, and the woman's cheeks are flushed with a deep rouge. Her head is turned slightly to the right, and she smiles slightly at the viewer. At first glance, it might be a depiction of any wealthy noble woman,

but the details of the portrait are where we can see the woman's complexity. The table where she's resting her elbow is holding an open book, loose pages of a manuscript, and an aurory, a mechanical model of the solar system. In the woman's left hand, she holds a white carnation, probably signaling its traditional associations with pure love and motherhood, or its nature as a hybrid, cultivated through human science. In the woman's right hand, if you look closely, you can see she's holding a compass, the tool of the mathematician. In 18th century French portraiture, the positioning of the compass symbolized different. fields, holding the points straight up signified abstractions, while downwards represented the measurement of the earth and matter. Here, our sitter holds the points of the compass horizontally,

an indication of her ability in both areas. The portrait is of a woman named Emily Duchat-Lay, who was not only a mathematician, but also a philosopher, physicist, writer, translator, and, yes, noble woman. The compass, and to be clear, I'm talking about a compass that is used to draw a circle, not a navigational compass. The compass is a particularly potent symbol in her life. In 1740, a few short years before she commissioned this portrait, Emily garnered great recognition within the scientific community

after winning a debate with the secretary of, of the Academy of Sciences, Jean-Jacques d'Orte de Moraine. When the publication of her book featured a correct rebuttal to the secretary's argument that force is proportional to velocity, she advised him not to draw a metaphorical epi against her. He responded, I implore you to observe that it would not be an epi. A compass suffices. That is quite enough to check the strikes of a fan.

He meant to dismiss Emily for her femininity. But in her portrait portrayed holding both a compass and a flower, Emily shows the viewer that she's capable of being a woman and being right. I'm Dana Schwartz and this is Noble Blood. In the early 19th century, many years after Emily Deschatley's death, a story began to circulate that explained how, she became a woman of science. The story comes to a simple conclusion.

She was just born that way. According to a French pamphlet of famous women, a servant in the home of three-year-old Emily attempted to improvise a toy out of a mathematical compass for the girl, closing the wooden tool and dressing it to look like a doll. Instead of accepting the gift as it was, the little Baron studied the figure

and undressed it. With this strange tool in hand at just three years old, she intuited its purpose and used it to make a perfect circle. This undoubtedly false anecdote tells us more about how history constructs identity than it does anything about Emily herself. As her biographer Judith Zinser points out, this framing presents Emily as a, quote, prodigy, anomaly, unlike any other female. In reality, we know very little about the early life of

Emily Duchet-Lay. We can say with certainty that she was born on December 17, 1706, in the Parisian parish of Saint-Rouche. She was the only girl of six children, though two of her brothers would die very young. At her birth, her father gifted her the minor title of Baron de Prouli, though it would automatically go to his eldest son upon his death. Her father was the breezily named Louis Nicola de Tonne de Bretois, a baron of a lesser noble family that had seen a recent rise in status, thanks to the favor of Louis XIV. Emily's grandfather was one of the King's most successful courtiers. And while his elder sons followed in his ambitious footsteps, Emily's father, Louis Nicolas, was perfectly happy just riding his dad's coattails. He was given

titles that came with privileges but no responsibilities, like being one of the king's, quote, first gentlemen of the bedchambers. That was a job that entailed watching the king used the toilet and keeping him company as he enjoyed his tea each morning. As one of the king's favorites, Louis Nicholas enjoyed certain other privileges, such as being sent away on diplomatic missions to cover up scandalous affairs. The greatest of such was his affair with a young Italian financier married to a Parisian official, in which he ultimately refused to claim paternity of the child he helped conceive. The king sent the woman to a convent in disgrace. As an adult, Emily defended her illegitimate sister's claim to inheritance against her cousin's attempts to silence

the by then 50-year-old woman. Emily was successful, and Parisian courts awarded her half-sister a settlement. Eventually, into Louis Nicholas's 40s, both the king and Louis Nicholas's family were fed up with his behavior, and it was arranged for him to marry 27-year-old Gabriel Anne de Foulet. While the Routes were still considered new blood, the Fouletes were elite members of the court. Gabrielle's mother was a lady in waiting to Queen Anne of Austria, and her father was a grand marshal of the king's army. In a memoir written by one of Emily's younger cousins, Gabrielle is described as an exceptionally beautiful woman, who was strict and superstitious, but well read in both theology and astronomy. Emily's father also had intellectual interests,

and he hosted a salon in the family home each Thursday. Louis Nicholas's salon drew big names from Parisian society, including the memoirist San Simone, the secretary of the French Academy of Sciences, Fontainelle, and one Voltaire himself. It's possible that Emily and her future collaborator and lover Voltaire might have met at one of these salons when Emily was just a child, but Voltaire actually dates their first meeting two years later. Emily's education was most likely typical for girls of her status. She would have had a governess who taught her basic reading, writing, and arithmetic, as well as, of course, how to be well-mannered and recite her prayers. When she was a little older, around seven or eight, evidence points to the possibility that she received a period of convent education. One of the major teaching orders for girls of the time described their responsibility as, quote, to teach the little girl's Christian piety, the virtues and good morals, and the works and exercises appropriate to their sex.

End quote. In Emily's first completed intellectual work, a translation and expansion of English philosopher Bernard Mandiville's social commentary, the Fables of the Bees, Emily dedicates space in her introduction to critiquing the state of girls' education. She began writing a bit hyperbolicly, quote, let us reflect a bit why at no time in the course of so many centuries a good tragedy, a good poem, a respected tale, a beautiful painting, a good book of physics, has ever come from the hand of a woman. Why do these creatures whose understanding appears in all things equal to that of men seem to be stopped by an invisible force on this side of a barrier. I leave it to naturalists

to find a physical explanation, but until that happens, women will be entitled to protest against their education. As for me, I confess that if I were king, I would wish to make this scientific experiment. I would reform an abuse that cuts out, so to speak, half of humanity. I would allow women to share in all the rights of humanity, and most of all those of the mind. In an earlier draft, she had explicitly stated, quote, if I were king, I would establish secondary schools for women. And quote, Emily was vigilant about her own education as an adult, making seeking up for lost years with tutors once she could hire them on her own. Secondary school for women was at this point just a fantasy.

By the time Emily was 15 or 16, potential marriages were already being negotiated. The lucky man would ultimately be Florent Claude, Marquis de Chet-Lay. In the eyes of society, he was a great match. He was older, 34 to her 18, a colonel in the King's Army, and a member of one of France's oldest noble lines. The Duchetles were one of the few families who could trace their lineage back to the 12th century princes who fought in the Crusades. From their marriage alliance, Emily gained new status and privileges, while her husband gained much-needed money. As summed up by one Versailles-Courte-Courtier, Monsieur Le Marquis de Chattelet, is a man of the highest rank, but is not rich. The marriage alliance was understood as exactly that, an alliance.

Neither Emily nor her husband would have been conditioned to have any romantic ideas about their union. However, the pair was luckier than many. They were not in love, no, but, they maintained a respectful and supportive relationship. Florent Claude was not an intellectual like his wife, but nonetheless he supported her pursuits steadfastly. He proudly boasted of her work to the court of Lorraine and took her book, Institutions de Physique,

to the printer on her behalf. Quote, happily I am sure of Monsieur de Chattelet, Emily once wrote to an associate, he is the most respectable and most estimable man I know. He was also away on military campaigns more often than not, which left Emily plenty of time and space to explore both her intellectual and amorous passions. Emily understood her responsibility as a wife was to carry on her husband's very prestigious family noble line, or as she plainly called it, quote,

the propagation of the species. The couple's first child, a daughter, was born almost exactly a year after their marriage. Their son and heir, Florent Louis, was born a year later. Emily gave birth to a third child, a son in 1733, but he would die within his first year. Emily spoke about his death objectively, calling it, quote,

one of the misfortunes of motherhood. But she also expressed her surprise at the extent of her distress and anger. In the dinner set catalogued amongst her possessions after her own death, 12 place settings are still accompanied by a single gilded baby spoon. When her living son was old enough,

Emily took his education upon herself after realizing his tutors were not up to her stuptom. standards. And though she rallied for better girls' schooling, Emily did not teach her daughter the same way. Her daughter received the traditional convent education and married well, young. Perhaps if Emily had been king. In the late 1720s and early 1730s, when her children were still very young, Emily lived the typical life of a young noble woman, engaging in what? what she would later call, Les Chos frivol.

Such frivolities, she believed, led to, quote, the neglect of my mind and understanding. Her daily routine, as established through her letters, went something like this. Each morning, her ladies' maid would wake her by drawing

the heavy curtains that lined her bedpost, and she'd take her preferred breakfast of coffee with cream and a roll, then would begin the long process of dressing, powdering her hair, and applying rouge and mouche. The rest of the morning was spent receiving visitors, followed by a trip to Paris's botanical gardens with her good friend, the Duchess de Saint-Pierre,

before returning home to dress for the theater at six. Nights would be spent at friends' homes or at one of Paris's many special events, like the annual opera ball, for which Emily had a custom yellow silk domino mask. She could not handle alcohol and thus avoided it, but she adored food and gambling. It was a world of, in her words, late nights and excesses. What's particularly interesting about Emily's critique

is that it's not moralizing or religious. These excesses and frivolities were not universally bad in her opinion, but rather bad for her. We do not know what eventually sparked her shift in priorities. As she later explained, it was, quote, by chance that she encountered people who think, and through them came to the key realization that she, too, was a thinking creature.

It would be years before she realized her full potential and published her own work, but by the early 1730s, a seed had been planted. In her discourse on happiness, she would go on to explain that because women have been, quote, condemned to be excluded from war, politics, and diplomacy,

she had to seek glory through another avenue. The answer for Emily was to seek glory through science and philosophy. In 1733, at age 26, Emily returned to Parisian society, after the birth of her third child. While she still indulged in her frivolities, her main focus now was on her new lessons in advanced geometry, with the mathematician and future president of the Academy of Sciences, Montpertu. While it was not uncommon for noble women to take on tutors,

Emily was certainly the most enthusiastic of her tutor's clients. She was no more known to wait in her carriage outside of his favorite cafe so their lesson could begin as soon as he was finished. Women were, of course, not allowed inside those spaces. Emily became the subject of Parisian gossip, believed to be covering up an affair with her tutor under the guise of behaving as an eager student. These rumors were likely borne out of a previous scandal. An effect she did have with a military officer that allegedly ended with him and another woman and Emily with a bottle of pills. While that affair was real, the truth of its dramatic ending is unknown. With her tutor, however, her passion was solely for mathematics.

Speaking of affairs, it's time to bring out our guest star of the episode. It was in the spring of 1733 that Emily became reacquainted with Voltaire. While the pair had briefly met in adulthood in 1729, their meeting on an April night in 1733 in St. Pierre's Opera Box marked the true beginning of their relationship. While Voltaire looms large in our cultural imagination, Emily's attraction to him wasn't a game. For one, the large looming man was actually quite small. He stood at approximately 5'3, compared to Emily's 5'6, and he was described by contemporaries as so slight he appeared as if he had consumption.

Their difference in stature was accompanied by a difference in status as well. Emily had married into one of France's oldest noble family. while Voltaire belonged strictly to the bourgeoisie. There was also the matter of his tempestuous relationship with the king's government and religious authorities, which often led to self-imposed exiles to avoid arrest. At the same time, Voltaire was polite, witty, wealthy, famous, and utterly enchanted by Emily.

He later told a friend, quote, there is a lady in Paris named Emily who, in imagination and in reason, surpasses the men who like to think they know a lot about the one and the other. The two would maintain years of friendship and intellectual collaboration before sex and love became involved. We can't know exactly what the two spoke about that first night at the opera box, but over the course of their long conversation, Voltaire offered to lend Emily a book. A few weeks after that meeting, he sent her a note explaining that he had fallen ill following a recent move and regretted that he

could not bring her the book he promised. He flirtatiously suggested she visit him to pick it up, but playfully noted, quote, I have more desire to see you than you have to console me. His evaluation of the disparity in their immediate feelings would prove evident even once their courtship began. He once told their friend, Abid de Sade, uncle to that Sade, incidentally, that Emily was a, quote, tyrant because one must pay tribute by speaking of metaphysics before speaking of love. strangely, no letters have survived between Emily and Voltaire themselves. Information regarding their intimate friendship is pulled from their descriptions to third parties. Emily did begin to visit Voltaire throughout the summer of 1733, usually accompanied by her friend Sanpierre and her lover. One such night, Voltaire's three guests played cards while he,

began to compose his verse, Epistle on Calumny, defending Emily from Parisian gossip. The poem begins, quote, Listen to me, respectable Emily. You are beautiful. Thus half of humankind will be your enemy. You possess a sublime genius.

You will be feared. In October of the same year, Voltaire enlisted Emily's help, working on his new play about Mexican history. Today, in the National Library of Russia, where Voltaire's personal library resides, thanks to Catherine the Great's purchase after his death, one can still find Emily's notes in the margins of his copy of the history of the conquest of Mexico. At the same time, Emily made progress in her own studies. A letter from Voltaire to his friend Assad, written in November, tells us that Emily, Emily had recently learned English in only 15 days. She had enlisted an Irish military officer as her tutor,

and after five lessons she could read fluently. Truthfully, he confessed to his friend, Madame de Chalet is a prodigy. She had also likely begun new mathematics lessons with her tutor's new protege, Clareau. Clareau's style of instruction was more in like, with Emily's thinking, and Emily would later use his lessons to teach her son. Most importantly, the two shared a passion and excitement for mathematics that her former tutor did not. In the 1740s,

while she worked on her translation of Newton's Principia, it was her new tutor Clareau, with whom she checked her calculations. By that time, she had surpassed the skills of her first teacher, who had struggled with Newton's calculus. An incident in the spring of 1734 would be a major turning point in both Emily and Voltaire's relationship and, respectively, their personal lives. In April, Voltaire's Letters Philosophic was published without royal sanction and therefore illegally in France. By May 3rd, a warrant was out for his arrest. He knew this was coming. The essays featured veiled mockery of the church,

but he went forward with publication despite warnings from friends. Voltaire began to move from place to place and planned to go into exile if necessary, comparing himself to Calvin and Ovid. A local officer presented an order for Voltaire's arrest personally to Emily. She wrote with Destrored. to Sad, envisioning, quote, my best friend with horrible health in prison, where he will surely die of sadness if illness doesn't kill him. She began to actively defend Voltaire to the

government and found an ally in her husband. The marquis, known chill guy, was fond of Voltaire despite his relationship with his wife, and he would continue to protect the trouble-prone philosopher for many years to come. authorities ultimately awarded the Marquis and Marquise Duchat-Lay the, quote, official authorization to sequester Voltaire, basically supervised house arrest. Exiled from Paris, Voltaire moved to the Duchat-Lay estate in Champagne. Writing to his closest correspondent, Voltaire praised, quote, Emily renders good offices to her friends with the same vivacity that she learned the languages

of mathematics, and when she has rendered all the services imaginable, she believes she has done nothing. Resuming her own life in Paris, Emily found herself at a loss, as she explained to Saad in July, quote, I am not accustomed to living without him, nor to the thought of losing him without recourse, that would poison all the sweetness of my life. She faced two more losses in quick succession. First, the death of her infant son, who he already mentioned. And then her tutor went to Basil with his mentor without warning, and her lessons ceased. Paris suddenly lost its luster, and she made the decision to join Voltaire in Champagne. By the fall, the pair fell into a routine of cohabitation. They both referred to the estate as my hermitage and considered it a place

devoted to intellect. For the next year, Emily spent her time between Paris and Champaign, between a life of society and a life of study. Their romantic relationship must have begun during this period, because in May of 1735, Emily referred to. refers to Voltaire as more than a friend for the first time. Reminiscing on her time in champagne, she reflected that she had, quote, tasted the happiness of living in the country with my lover. After much internal debate, she came to the decision that she would leave Paris for good, becoming a full-time resident at the hermitage. Friends advised her against such a drastic move and didn't believe she was capable of abandoning her beloved Parisian lifestyle.

Her response was decisive. Quote, I love Voltaire enough to sacrifice all that I could find pleasurable and agreeable in Paris for the happiness of living with him without dangers, and the pleasure of tearing him away in spite of himself from his imprudences and his destiny. In the summer of 1735, her servants packed her poor. bags. That's the end of part one of our story about Emily Duchet-Lay, but keep listening after a brief sponsor break to hear about a particularly interesting conversation that shaped Emily's life. Close your eyes, and you can hear the entire world come alive. 2026 FIFA World Cup

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Apple Podcasts, or wherever you get your podcast. Emily's decision to leave Paris for the countryside was supported by a figure from her childhood. Fontenelle, her father's associate, and former secretary of the Academy of Sciences. On June 15th, Emily went for a two-hour walk in the Tulare Garden with the then-78-year-old writer. Bringing up her dilemma, he responded in a way she would understand as a fellow mathematician.

He said, quote, It is only a question of calculating, and wisdom always holds the counters in her hand. It was that very night she made her decision to leave. When she wrote her discourse on happiness in the late 1740s, she would repeat that advice word for word. Noble Blood is a production of IHeart Radio and Grim and Mild from Aaron Manky. Noble Blood is hosted by me, Dana Schwartz. Writers for Noble Blood are Hannah Johnston, Hannah Zwick,

Paul Jaffe, Natasha Lasky, and me, Dana Schwartz. The show is edited and produced by Jesse Funk and Nome's Gripen with supervising producer Rima Il Kali and executive producers Aaron Manke, Trevor Young, and Matt Frederick. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. Joy is essential and it's also elusive, but now there's a new and exciting way to start your journey toward a more joyful example. Joy 101. It's a new podcast hosted by me, Hoda Kotby. If you're craving inspiration to maximize your joy, tune into these candid, uplifting, and moving on-air chats. Open your free IHeart Radio app. Search Joy 101 and Listen Now. Joy 101 with Hoda Kotby is presented by CVS. Every family has its secrets. But what happens when you discover that your dad has been living a double life?

That is not the look of an innocent man. Is everyone lying to me about who they are? I felt such desperation. I felt it was what I had to do. Listen to Deep Cover the Family Man on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. I've been hearing for decades that the markets can solve climate change. Today, we have more incentives for market solutions than ever, and emission are rising. On this season of drilled, Carbon Cowboys, the story of three market solutions

colliding in one multinational boondoggle. You got to give Bruce of the guy's credit. They're Republican. They don't give a shit about it in this now. Listen on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. This is an IHeart podcast. Guaranteed Human.