Emilie du Châtelet’s One True Love (was not Voltaire)!

Gabrielle Birchak/ July 12, 2022/ Early Modern History, Modern History, Uncategorized

Gabrielle Emi­lie le Ton­neli­er de Bre­teuil, mar­quise du Châtelet, also known as Emi­lie du Châtelet was born in Paris, France, on Decem­ber 17, 1706. Her moth­er was Gabrielle Anne de Froul­lay, Baronne de Bre­teul, and her father was Louis Nico­las le Ton­neli­er de Bre­teuil, who was the prin­ci­pal sec­re­tary to King Louis XIV. The King always found favor with her father because they both had rep­u­ta­tions of seek­ing the com­pa­ny of oth­er women.

Her ear­ly edu­ca­tion is spec­u­la­tive. What can be known about it comes from resources that describe what edu­ca­tion would be like for a young girl of high sta­tus. She pos­si­bly stud­ied along­side her younger broth­er, who was edu­cat­ed at home.[1] Her father would hire tutors for her. By age twelve, she was receiv­ing an edu­ca­tion in lit­er­a­ture, math, and sci­ence. Du Châtelet was flu­ent in Ger­man, Greek, Ital­ian, and Latin. An inven­to­ry of her father’s books shows writ­ings by poets Jean de la Fontaine and Paul Scar­ron, as well as Euclid and René Descartes. Fur­ther inven­to­ry of her father’s prop­er­ty shows that she had access to bil­liards, cards, board games, fenc­ing gear, and hors­es for rid­ing.[2]

She was musi­cal­ly gift­ed and could play the harp­si­chord, sing opera, and dance. No doubt, du Châtelet received a well-round­ed edu­ca­tion and had a broad inter­est in many things.

But her expect­ed role in life was not to uti­lize those skills. As the baron’s daugh­ter, she was behold­en to a suit­er named Flo­rent-Claude, mar­quis du Châtelet-Lomont. Lomont was twelve years old­er than her. For her fam­i­ly, he was a nec­es­sary fix­ture in their lives because he would be able to solid­i­fy their con­nec­tions to roy­al­ty. Hence, her mar­riage would be a busi­ness deal. Though her father had elite sta­tus, it was not an ances­tral sta­tus. Instead, her father had worked his way up in the roy­al ser­vice, earn­ing his posi­tion among the King’s staff. Her father, de Bre­teuil, rep­re­sent­ed the less­er nobil­i­ty who had risen to elite sta­tus through ser­vice to the crown. Alter­na­tive­ly, her suit­or would come from an ancient lin­eage of Euro­pean roy­al­ty, all for the dowry price of 150,000 livres. In U.S. dol­lars, in today’s econ­o­my that would equate to a lit­tle less than $11,000,000.

Thus, for $11,000,000, her hus­band was made the gov­er­nor of Semur-en-Aux­ois in the French king­dom of Bur­gundy. Though they spent time in Paris between 1726 and 1733, du Châtelet and her hus­band lived in Semur-en-Aux­ois, where she gave birth to three chil­dren. Sad­ly, around 1734, her son, François-Vic­tor, who was only one year old, died. She knew that her mar­riage would not be that of romance or ide­al­ism. Instead, as she wrote in her trans­la­tion of Mandeville’s Fable that she pro­ceed­ed in “the prop­a­ga­tion of the species.”[3]

After her third child was born, she moved back to Paris. In let­ters to friends, she wrote that she want­ed to con­tin­ue her pre­vi­ous activ­i­ties with prom­e­nades, vis­its to the the­ater and the opera, as well as evenings din­ing and drink­ing with friends. How­ev­er, she also had oth­er plans. She had found inter­est in the math­e­mati­cian Pierre-Louis More­au de Mau­per­tu­is. Thus, dur­ing her time in France, she also began to focus on advanced geom­e­try, alge­bra and the physics of Isaac New­ton. She became so immersed in this iden­ti­ty that for many of the paint­ings she com­mis­sioned, she is seen with a book or a pro­trac­tor. No doubt, du Châtelet made it known that her true love was mathematics.

The math­e­mat­ics that she learned from Mau­per­tu­is reflect­ed the edu­ca­tion that he received. He was a promi­nent aca­d­e­m­ic and was elect­ed to the French Acad­e­my and France’s Acad­e­my of Sci­ences, of which he would become the leader of the dai­ly gath­er­ings.[4] He often attend­ed the cafes in Paris and trav­eled with­in the social cir­cles of oth­er New­ton­ian aca­d­e­mics. Sev­er­al years before Mau­per­tu­is met du Châtelet, he trav­eled to the Uni­ver­si­ty of Basel in Switzer­land, where he learned from Johann Bernoul­li, one of the ear­li­est con­trib­u­tors to the devel­op­ment of cal­cu­lus. So, when Mau­per­tu­is met du Châtelet, he was well versed in alge­bra, geom­e­try, and cal­cu­lus. He encour­aged her to read math­e­mat­i­cal works from authors that includ­ed Nico­las Guis­nee and Guil­laume de l’Hôpital, one of the founders of dif­fer­en­tial cal­cu­lus.[5]

Still, her part-time instruc­tor Mau­per­tu­is, was not enough for du Châtelet. She would often write him in an effort to engage in intel­lec­tu­al dis­course. In Jan­u­ary 1734, she wrote him ask­ing if he could give her some math­e­mat­i­cal prob­lems to work on to con­tin­ue her stud­ies. He often did not respond as urgent­ly as she want­ed. While at a wed­ding in April 1734, she wrote a let­ter to him stat­ing, “it is not for me that I wish to become a math­e­mati­cian; it is out of my respect for you.” How­ev­er, short­ly after that, she sought out the math­e­mat­i­cal exper­tise of Maupertuis’s pro­tégé Alex­is-Claude Clairaut. Dur­ing this time, Clairaut also began to tutor François-Marie Arou­et, who went by the pen name Voltaire.

It was in 1733 that du Châtelet met Voltaire. Short­ly after meet­ing her, he had told a friend that he had nev­er seen such an incred­i­ble crea­ture before. Like­wise, by Decem­ber 1733, she also had writ­ten to a friend about how Voltaire charmed her.[6] Even though she was attract­ed to Voltaire and even­tu­al­ly engaged in a long-last­ing inti­mate rela­tion­ship with him while she was mar­ried, she also had oth­er lovers. This was com­mon­place in France. How­ev­er, at times her love life became the sub­ject of pub­lic scruti­ny, which did not serve her well, even today as she is often referred to as Voltaire’s lover.

By 1735, du Châtelet began to com­mit more of her time in Cham­pagne, France, and Brus­sels, which at that time was part of the region of Aus­tria Nether­lands. Her rela­tion­ship with Voltaire flour­ished, and she found great encour­age­ment and sup­port from her lover. Dur­ing this time, she began to define her­self as a think­ing crea­ture. Fur­ther­more, her hus­band Lam­ont equal­ly embraced Voltaire as her lover. He had no prob­lems accept­ing that he was her muse and ful­ly accept­ed that Voltaire was part of the “expand­ed house­hold.”[7] Fur­ther­more, her hus­band and Voltaire had become trust­ed friends, as Lam­ont often helped him devel­op his works.

All the col­ors of nature come from this prop­er­ty of light dis­cov­ered by Mr. New­ton, and which he calls its refrangibility. 

– Emi­lie du Châtelet

Voltaire and du Châtelet car­ried on with great intel­lec­tu­al and sci­en­tif­ic dis­course. They set up a lab­o­ra­to­ry in her home and began to run exper­i­ments with fire. Inter­est­ing­ly, Voltaire want­ed to dis­prove the the­o­ry that fire is a mate­r­i­al sub­stance. Du Châtelet also sought to dis­prove this same the­o­ry. How­ev­er, she dis­agreed with Voltaire’s the­o­ries. Thus, they both immersed them­selves in the research of fire.

By 1737, she was engaged in a friend­ly com­pe­ti­tion with Voltaire on the prop­er­ties of fire. This became the top­ic of an essay she sub­mit­ted anony­mous­ly to the Paris Acad­e­my of Sci­ences for the 1738 sci­ence con­test. Voltaire also sub­mit­ted his essay for the same com­pe­ti­tion. How­ev­er, nei­ther one of them won. Even so, both of their papers were pub­lished along with the top three win­ners of the com­pe­ti­tion. The first place went to the bril­liant Swiss math­e­mati­cian and physi­cist Leon­hard Euler.

Thus, in 1738 her first pub­lished paper, Essay on the Nature and Spread of Fire, made her the first woman to have a sci­en­tif­ic paper pub­lished by the Acad­e­my. What is most excit­ing about this paper is that in chap­ter four, du Châtelet writes about the research she con­duct­ed on assort­ed col­ors of light. What she found was that dif­fer­ent col­ors of light had their own dis­tinct heat­ing pow­er.[8] Thus, du Châtelet fore­saw a behav­ior that we now refer to as infrared radi­a­tion. She pre­dict­ed this dis­cov­ery before it was even dis­cov­ered. She was indeed a bril­liant woman!

A cou­ple of years before they entered the com­pe­ti­tion, in 1736, Voltaire began work­ing on his book Ele­ments of the Phi­los­o­phy of New­ton. Du Châtelet had helped him trans­late Newton’s book and under­stand Newton’s physics. The fron­tispiece to his pub­lished work shows Voltaire trans­lat­ing Newton’s work. The man­u­script is being illu­mi­nat­ed by a mir­ror that is held by a muse. The muse rep­re­sents du Châtelet.

While help­ing Voltaire, du Châtelet became inspired. As a result, she also began writ­ing a trea­tise on New­ton­ian physics. In 1740, du Châtelet anony­mous­ly pub­lished her trea­tise Foun­da­tions of Physics. It was her inten­tion to cre­ate a work that explained Newton’s philo­soph­i­cal sys­tem. How­ev­er, Foun­da­tions of Physics was not only a reflec­tion of Newton’s work but also of the immi­nent math­e­mati­cian, physi­cist, and poly­math Got­tfried Wil­helm Leib­niz. This was a unique move on her part because, in philo­soph­i­cal cir­cles, sci­en­tists were debat­ing the dif­fer­ences between the physics of New­ton and the meta­physics of Leib­niz. Alter­na­tive­ly, du Châtelet’s Foun­da­tions of Physics sur­passed the debate and bril­liant­ly high­light­ed the merg­ing of two the­o­ries with­in one body of work. By doing this, she cre­at­ed a prece­dent that val­i­dat­ed the philoso­phies that Immanuel Kant embraced.

The Foun­da­tions of Physics far sur­passed Voltaire’s work in detail and knowl­edge. This is prob­a­bly because of her exten­sive math­e­mat­i­cal capa­bil­i­ties. Her work looked at the laws of nature, the mechan­ics of New­ton­ian physics, and the find­ings of Galileo Galilei. This work also addressed the­o­ries on space, time, and mat­ter. Foun­da­tions of Physics also detailed gravity’s affect on free-falling objects, the pen­du­lum, and the orbits of our plan­ets. But what makes her trea­tise so unique is that she also includ­ed the­o­ries on meta­physics as she addressed the prin­ci­ples of rea­son­ing con­cern­ing the knowl­edge of God. With­in two years of pub­li­ca­tion, this work had been copied, trans­lat­ed into mul­ti­ple lan­guages, and dis­trib­uted beyond Europe’s borders.

Anoth­er unique and ground­break­ing dis­tinc­tion that came out of du Châtelet’s Foun­da­tions of Physics was her argu­ment in favor of Leibniz’s the­o­ry that a body’s force equals the body’s mass times the square of the veloc­i­ties. Leib­niz had stat­ed that the for­mu­la for force was 

F=mv^2

that he referred to as vis viva, which trans­lates into “a liv­ing force.” While pre­sent­ing her argu­ment in Foun­da­tions of Physics, du Châtelet con­demned the pri­or work of the renowned French math­e­mati­cian Jean-Jacques d’Ortous de Mairan, who argued in favor of René Descartes’s the­o­ry that vis viva was equal to mass times veloc­i­ty, stat­ing that the for­mu­la was

F=mv

instead of

F=mv^2.

What is inter­est­ing about these two equa­tions is that Leibniz’s descrip­tion of vis viva was the ear­ly expres­sion of the con­ser­va­tion of ener­gy that we now refer to as kinet­ic ener­gy. The for­mu­la for kinet­ic ener­gy is

K.E.=\frac{mv^2}{2}.

How­ev­er, de Mairan’s descrip­tion of vis viva, as argued by New­ton and Descartes, described force as a con­ser­va­tion of momen­tum. In oth­er words, de Mairan, New­ton, and Descartes argued that the momen­tum of force is con­served and that force is equal to the object’s mass times the object’s veloc­i­ty. Today this equa­tion defines momen­tum and is writ­ten as

P=mv.

Thus, even though de Mairan and du Châtelet were close to the def­i­n­i­tion of force, he was not hap­py that she had con­demned his work. Thus, he set out to defend his work and dimin­ish her intel­lect. At this point, it was 1741, and the author of Foun­da­tions of Physics was still con­sid­ered anony­mous, even though some knew that the author was du Châtelet.

Thus, the vis viva debate ensued. How­ev­er, his actions back­fired. By call­ing her out, de Mairan put du Châtelet on the same plat­form as oth­er renowned math­e­mati­cians of her time and val­i­dat­ed her intel­lec­tu­al sta­tus with­in the male-cen­tric math com­mu­ni­ty. Fur­ther­more, du Châtelet replied to de Mairan’s defense. Using her excep­tion­al math­e­mat­i­cal skills, she refut­ed each of his points and fur­ther sup­port­ed her stance on the def­i­n­i­tion of vis viva.

In 1742, she pub­lished a sec­ond edi­tion of Foun­da­tions of Physics. This edi­tion was print­ed under her name and includ­ed her vis viva debate with de Mairan. This edi­tion was trans­lat­ed into Ger­man and Ital­ian. In Italy, the Ital­ian trans­la­tion of Foun­da­tions of Physics was used by Lau­ra Bassi, the first female to become the high­est-paid pro­fes­sor in Europe. In 1746, du Châtelet was elect­ed to the Bologna Acad­e­my of Sciences.

Du Châtelet also wrote a French trans­la­tion and com­men­tary on Isaac Newton’s Math­e­mat­i­cal Prin­ci­ples of Nat­ur­al Phi­los­o­phy, which, at that time, was the foun­da­tion for under­stand­ing the fun­da­men­tal laws of physics. Even in her ninth month of preg­nan­cy, she sched­uled her days so that she could devote every spare minute to the trans­la­tion of Newton’s work and her math­e­mat­ics. Her love for math car­ried her through to the birth of her fourth child. How­ev­er, in 1749, her health declined rapid­ly with­in six days after giv­ing birth. She had dif­fi­cul­ty breath­ing and a vio­lent headache, as one of her physi­cians not­ed. She resigned to bed rest and, in the process, devel­oped a blood clot with­in her pelvis or legs. As the blood clot broke up, it trav­eled through­out her body to her heart and lungs. Sad­ly, on Sep­tem­ber 10, 1749, the 42-year-old du Châtelet died of pul­monary embolism.[9]

Du Châtelet died before she had a chance to release her French trans­la­tion of Math­e­mat­i­cal Prin­ci­ples of Nat­ur­al Phi­los­o­phy. However,her trans­la­tion was pub­lished posthu­mous­ly in 1756 and became France’s stan­dard work on physics. Also, after her death, Denis Diderot and Jean le Rond d’Alembert wrote about her philoso­phies, math­e­mat­ics, and sci­en­tif­ic writ­ings in their work known as Ency­clo­pe­die.

So, even though many know Gabrielle Emi­lie le Ton­neli­er de Bre­teuil, mar­quise du Châtelet as the woman in Voltaire’s life, she was much more than his lover. She was a gift­ed and accom­plished math­e­mati­cian. She allud­ed to infrared radi­a­tion, she set the foun­da­tions for a phi­los­o­phy that val­i­dat­ed Kant’s ide­al­ism, and, through her dis­pute with de Mairan, she estab­lished her­self as a promi­nent female math­e­mati­cian in a male-cen­tric world. She was fear­less, out­spo­ken, and devot­ed her­self whole­heart­ed­ly to study­ing math and sci­ence. She knew she would encounter oppo­si­tion by the mere fact that she was a woman. And that did not deter her. She knew that her intel­lect would be her most out­stand­ing defense, and she was not afraid to use her knowl­edge as her great­est weapon. Du Châtelet was also a woman who inspired oth­er women and con­tin­ues to do so with her tremen­dous and accom­plished legacy.

BIBLIOGRAPHY

Boda­nis, David. Pas­sion­ate Minds: Emi­lie Du Châtelet, Voltaire, and the Great Love Affair of the Enlight­en­ment. New York, NY: Three Rivers Press, 2006.

Project VOX. “Du Châtelet (1706–1749).” Research. Accessed June 29, 2022. https://projectvox.org/du-chatelet-1706–1749.

Project VOX. “Essai Sur l’Optique – Chapitre 4: De La For­ma­tion Des Couleurs.” Research. Accessed June 29, 2022. https://projectvox.org/du-chatelet-1706–1749/texts/essai-sur-loptique/04-de-la-formation-des-couleurs.

Slavov, Matias. “A Prob­lem In Du Châtelet’s Meta­phys­i­cal Foun­da­tions Of Physics.” His­to­ry of Phi­los­o­phy Quar­ter­ly 37, no. 1 (2020): 61–76.

Zinss­er, Judith P. Emi­lie Du Chatelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006.

[1] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 28.

[2] Boda­nis, David. Pas­sion­ate Minds: Emi­lie Du Châtelet, Voltaire, and the Great Love Affair of the Enlight­en­ment. New York, NY: Three Rivers Press, 2006, 22.

[3] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 33.

[4] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 67.

[5] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 68.

[6] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 77.

[7] Zinss­er, Judith P. Emi­lie Du Châtelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 105.

[8] Project VOX. “Essai Sur l’Optique – Chapitre 4: De La For­ma­tion Des Couleurs.” Research. Accessed June 29, 2022. https://projectvox.org/du-chatelet-1706–1749/texts/essai-sur-loptique/04-de-la-formation-des-couleurs.

[9] Zinss­er, Judith P. Emi­lie Du Chatelet — Dar­ing Genius of the Enlight­en­ment. New York, NY: Pen­guin Books, 2006, 279.