Mme du Châtelet informs you sir that tonight at her desk, while scribbling some note about Newton, she felt a little summons. This little summons was a daughter who appeared immediately. She was laid down on a quarto tome of geometry.
Voltaire, Letter to the Marquis d’Argenson, 4 September 1749
Émilie du Châtelet, wrote Voltaire, ‘was a great man whose only fault was being a woman’. Du Châtelet has paid the penalty for being a woman twice over. In her own lifetime, she fought for the education and the publishing opportunities that she craved. Since her death, she has been cast in the shadow of her lover, Voltaire, who excelled in self-promotion. ‘I was destined for immortality from the time of my birth,’ he boasted, and his reputation still distorts Enlightenment history.1
For more than two centuries du Châtelet (1706-49) has been cast as Voltaire’s mistress, as though she were his possession or at best an intelligent secretary. Voltaire himself told a different story. He appreciated the effect of du Châtelet’s presence on his own work, and praised her as a ‘great & powerful Genius, the Minerva of France’. Figure 16, organised by Voltaire, illustrates how he acknowledged her scientific superiority. It is the frontispiece of a book about Newtonian philosophy. Du Châtelet and Voltaire worked on it together, but only his name is on the title-page. In the picture, du Châtelet hovers above Voltaire’s head, casting Newton’s divine wisdom down onto his hand – Voltaire is the scribe, and she is the knowledgeable interpreter.2
In this allegorical image, Newton sits suspended in the clouds, floating like a saint between God and ordinary mortals. This sanctification started in his own lifetime and has continued ever since. Like Descartes, Newton has become such a heroic figure in science’s past that history and legend sometimes blend into one another. In conventional accounts of his life, it can be hard to pick apart myth and reality. Newton and his achievements have been tailored to fit the heroic model of scientific discovery. Alexander Pope’s famous couplet, originally intended for Newton’s tomb in Westminster Abbey, launched Newton’s posthumous career as a legendary figure from England’s distant past:
Fig. 16 Émilie du Châtelet as Voltaire’s Newtonian inspiration. Frontispiece of Voltaire’s Élémens de la philosophie de Newton (1738), engraved by Jacob Folkema after Louis-Fabricius Dubourg.
Nature, and Nature’s Laws lay hid in Night.
God said, Let Newton be! and all was Light.3
In these lines, Pope presents Newton as a divine messenger who flicked the switch of Enlightenment illumination, thus immediately and single-handedly revealing the truths of nature that lesser beings had groped for unsuccessfully.
The falling apple story is another way of presenting the same concepts. Newton himself originated this myth of instantaneous insight, this tale of a Eureka moment when he (allegedly) realised in a flash of inspiration that the same laws that make an apple fall to the ground must also control the paths of the planets through the heavens. Was Newton really inspired by a falling apple? Other anecdotes about Newton that were once common knowledge have now been forgotten – such as discovering that his dog Diamond had upset a burning candle over yet another scientific masterpiece and destroyed it for ever, or borrowing his fiancée’s finger to tamp down the tobacco in his pipe. Because these have been rejected as fables, does it make the falling apple tale more or less likely?
Sound-bite versions of the past tell the same story more prosaically. A typical one-sentence encapsulation reads: Isaac Newton was one of the greatest geniuses who ever lived, and he revolutionised the way that people thought about the world. Here is a slightly fuller account of that interpretation . . .
Isaac Newton was born in 1642, the same year that Galileo died, when the Catholic Church still judged it heretical to believe that the Earth goes round the sun. By the time of his own death, in 1727, views about the universe had changed for ever, and scientific truth had defeated religious obstinacy. His greatest book was his Principia (or Mathematical Principles of Natural Philosophy) of 1687. Written in Latin and geometry, Newton’s Principia became a new scientific Bible. As well as setting out his three laws of motion, which form the basis of modern mechanics, Newton’s Principia described the force of gravity that holds the universe together. For the first time, one simple mathematical law could be used to describe events in the heavens as well as on the earth. Revolving planets, falling apples, bouncing billiard balls – from now on, a single neat formula wrapped up their behaviour and converted the chaos of nature into stable, predictable order.
Newton’s other major work was the English Opticks, not published until 1704, but summarising a lifetime’s research into telescopes, prisms and rainbows. After centuries of debate, Newton had demonstrated once and for all that ordinary sunlight is made up of seven basic colours. It was in Opticks that he stressed the importance of experiments, and he bequeathed clear, detailed instructions to his successors. He also included a long list of speculations that dominated scientific enquiry for the next hundred years, not just in physics, but in chemistry, biology and the social sciences as well.
Newton spent thirty years immured within Cambridge, absorbed in esoteric mathematical calculations and alchemical investigations, a lonely scholar whose work was too abstruse for all but the most brilliant to understand. But for another thirty years after that, he was the doyen of European science, holding court at his London home, presiding over the Royal Mint and the Royal Society. Voltaire crowned Newton the king of natural philosophy, the genius who had surpassed all his predecessors to rule supreme. ‘Honoured by his compatriots,’ reported Voltaire, ‘he was buried like a king who had done well by his subjects . . . Very few people in London read Descartes, whose works, practically speaking, have become out of date.’4
Nothing in this potted biography is factually false, yet does it convey a true impression of Newton’s life and influence? Even assessing the validity of apparently straightforward statements can be difficult, because many of them depend on opinion rather than fact. According to Voltaire and other Enlightenment ideologues, Newton represented the power of reason over religion. Yet how can this be compatible with Newton’s own books, in which he gave God an indispensable role in the day-to-day running of the cosmos? The past is always open to revision, and older interpretations now seem misleading. Newton’s ideas were not immediately accepted; following his experimental instructions did not always yield the results he claimed. Instead of celebrating Newton as the first modern scientist, many historians now regard him as the last of the great alchemical magicians.
So how much faith can we put in Voltaire’s claim that Newton toppled Descartes overnight? For one thing, this was a battle between two countries as well as between two cosmologies. Enlightenment natural philosophers boasted about their love of truth, but the intellectual world was riven with international rivalries, which were just as bitter as political hostilities. As an English mathematician commiserated with a French colleague, ‘We have our Newton, the Germans their Leibniz, and you your Descartes.’5 Voltaire had his own axe to grind. After a period in exile, he pursued his agenda of taunting the French authorities by lauding England and denigrating France. By deliberately exaggerating Newton’s success, Voltaire could criticise French culture.
Newton did eventually oust Descartes in France, but only after a long propaganda campaign waged by his supporters. One person who played a key role in bringing Newton before the French reading public was Émilie du Châtelet, a superbly energetic woman who committed herself to academic study with almost obsessive fervour. ‘Ambition is an insatiable passion,’ she reflected, and she made herself into a leading expert on Newton. The birth of du Châtelet’s fourth child killed her, yet by then she was internationally renowned for her scientific knowledge.
Du Châtelet had an impressive range of expertise. Her annotated translation of Newton’s Latin Principia remains the only complete version in French. As well as her scholarly text synthesising Europe’s three rival philosophers (see Figure 12), she collaborated in producing two simpler accounts of Newton’s ideas which helped to displace Descartes’s supremacy. In addition, she wrote and translated works on other subjects – the nature of fire, happiness, the Bible, Greek poetry, morality. No wonder that she was praised in print for ‘holding an advantage over Newton himself: she united the depth of Philosophy with the most acute & delicate taste for Literature’.6
‘Judge me for my own merits,’ protested du Châtelet; ‘do not look upon me as a mere appendage to this great general or that renowned scholar.’ Figure 16 shows her interposed between two famous men, Voltaire and Newton, as if she were a medium of communication between them. Listening to her plea for recognition in her own right entails giving her an independent existence, uneclipsed by the shadows of these two Enlightenment geniuses. But how faithfully can this be done? Like other women of this period, she seems to behave inconsistently, and gives contradictory accounts of herself. Sometimes du Châtelet sounds as if she had reconciled herself to a secondary role as translator and interpreter, as though she sited herself in Newton’s shadow. ‘God has refused me any kind of genius,’ she confided to one correspondent; ‘I spend my time unravelling truths discovered by other people.’7
In some ways her behaviour conformed to stereotypical expectations for an aristocratic hostess: she loved clothes, dancing and entertaining. On the other hand, this apparent resignation to her feminine status clashed with her dedication to Newtonian natural philosophy, which meant constantly transgressing the norms for her society. Du Châtelet did engage in unconventional activities, yet at the same time she remained confined by traditional demands. Some of these she imposed on herself; in other cases, she seems to yield to pressure from her contemporaries. As if conditioned from birth into a form of psychological captivity, even in the midst of achievement she self-deprecatingly judged herself to possess only a second-rate talent.8
Faced by overt exclusion as well as ingrained doubts about her own capacity, du Châtelet was trapped between conflicting, unsatisfactory stereotypes – the learned eccentric, the flamboyant lover, the devoted mother. Even now, biographers plump for one or another of these hackneyed models. ‘I am in my own right a whole person,’ she insisted.9 Hopefully she would have appreciated this version of her life.
Émilie du Châtelet was tall and beautiful. Many intellectual women would object to an account that started with their looks, but du Châtelet was extremely concerned about her appearance. She was proud of being included in the frontispiece of a book on Newtonian philosophy (Figure 17), which shows her dressed in an elegant low-cut gown, strolling in some palace grounds. She is discussing Newton’s ideas with her Venetian friend Francesco Algarotti, who had written the book while he was staying at her country mansion. ‘Did you recognise me in the picture?’ she boasted to Pierre Maupertuis, her close friend and mathematics teacher. Du Châtelet spent a fortune on her clothes and jewellery, acquiring the money from her husband, a succession of lovers, and card games in which her mathematical skills made her an impressive opponent – although she was also a heavy loser.10
Her success at court and with men made her an easy target for jealous rivals: ‘Imagine a tall, dry woman . . . with a narrow face, a pointed nose, a dark flushed complexion . . . and there you have the face of the fair Émilie, a face with which she is so pleased that she spares no effort to display it: curls, top-knots, stone jewellery, glass jewellery, everything in great profusion.’11 Malicious, yes, but hardly the description of a frumpy scholar. Du Châtelet lived at a high pitch, and devoted the same intensity to gambling, dressing and loving as she did to learning. When deadlines were close, she allegedly scarcely slept, plunging her hands into ice-cold water to keep herself awake. The major goal of life, she believed, was to be happy, and she gained the reputation for living enthusiastically. One should, she taught, indulge, yet also balance one’s passions for food, sex and work.
Fig. 17 Émilie du Châtelet discussing Newton with Francesco Algarotti. Frontispiece of Francesco Algarotti’s Il Newtonianismo per le dame (Naples, 1737), engraved by Marco Pitteri after Giambattista Piazetta.
Obviously brilliant as a child, du Châtelet resented the discrimination that made it impossible for her to pursue the same path through life as a man. On the other hand, unlike now, there were no conventional career tracks to follow even for a man who wanted to study science. Like women, men had to carve out their own routes to success, especially if they were not born into rich families. Protecting her own interests was important for du Châtelet. Women, she wrote, need to foster their own happiness, and so should study ‘to console them for everything which makes them dependent on men’.12
Born into a wealthy aristocratic family, du Châtelet (née Gabrielle Émilie Le Tonnelier de Breteuil) benefited from an enlightened father. Instead of sending her to a convent school, he decided that she should be taught at home, and – like Elisabeth of Bohemia – she received the sort of education that was more typical for boys than for girls. She could apparently speak six languages when she was only twelve years old, including English as well as Italian. Languages, modern literature, the classics – she excelled in them all. Free to browse in her father’s well-stocked library, she displayed such precocity that her father enjoyed showing her off to his intellectual friends.
As with young male prodigies, du Châtelet’s learning was almost exclusively in the humanities. She encountered the philosophies of Leibniz and Descartes at seventeen, but it was only ten years later that she started to immerse herself in mathematics and Newtonian philosophy. By then, she was married to an older army officer, the Marquis du Chastellet (Voltaire later revised the spelling), had given birth to three children (two of whom survived) and was simultaneously developing friendships with two other men, Voltaire and Pierre Maupertuis. Maupertuis was a controversial young member of the Paris Academy who had just published France’s first book on astronomy to be based on Newton’s ideas. Because of the strong Jesuit influence, Cartesian philosophy still reigned, and Newtonian natural philosophy was not taught in the schools and universities until the second half of the century. She persuaded Maupertuis to teach her mathematics, although she often accused him of not taking her seriously enough. By studying Newton, du Châtelet allied herself with a radical faction, and so was making a political as well as a scientific decision.
Much to her frustration, as a woman, she was excluded from two places in Paris where Newton was discussed: the Wednesday meetings of the Royal Academy and – less formally – Gradot’s café. Paradoxically, this woman who danced and gambled in Parisian palaces led an isolated life, mocked as a freakish woman yet at the same time unable to enter male academic circles. She was trapped between the sexes. The German philosopher Immanuel Kant respected her ideas, yet felt that she must be some sort of hybrid creature: ‘a woman who . . . conducts learned controversies on mechanics like the Marquise de Chatelier might as well have a beard.’13
Assessing du Châtelet’s character is difficult. For one thing, she self-protectively concealed herself within deceptive outer shells. ‘Émilie puts so much effort into appearing what she is not,’ quipped one of her acquaintances, ‘that no one knows any longer who she really is.’14 To add to the problem, many reports are biased. At the time, snide gossips almost certainly exaggerated any strangeness in her behaviour, and distorted incidents that may or may not have happened. Even modern biographies are not necessarily reliable. According to them, du Châtelet resorted to dressing as a man so that she could drink coffee at Gradot’s with Maupertuis and his friends. This anecdote has been repeated so often that it has acquired the aura of truth, yet no original source has ever been given. Historians sometimes sneer that her attachment to mathematics was a mere flirtation, a ruse to gain the attention of scholars who became her lovers. Perhaps it was initially – being clever doesn’t preclude being beautiful and sexy. But what is certain, and far more important, is that she dedicated herself to a gruelling programme of mathematical study with Maupertuis and other tutors, including his close friend Aléxis-Claude Clairaut.
It remains uncertain whether she had an affair with Maupertuis, but there is no doubt about her relationship with Voltaire – they fell passionately in love. Voltaire was in serious trouble: his book praising England and criticising France had been banned, and a warrant was out for his arrest. Du Châtelet sent him off to Cirey, her run-down estate in the country that had formed part of her marriage arrangements. ‘My Hermitage’ she called it – and Cirey was conveniently near the border so that Voltaire could escape if the authorities managed to track him down.15 While Voltaire started to pour money into renovations, she stayed in Paris, where – as well as studying and enjoying herself – she tried to restore his reputation.
In October 1734, du Châtelet joined Voltaire in Cirey for a couple of months. After making his alterations, and spending more of his money, she retreated to Paris, Maupertuis and the card tables. The following March, Voltaire was awarded his freedom, and he presented du Châtelet with an ultimatum: live separately in Paris, or together in rural seclusion at Cirey. She made up her mind. By the summer, Voltaire and du Châtelet were ensconced together at Cirey, mutually embroiled in a private world of intense intellectual activity entwined with romance.
The first step was to buy books for their libraries and instruments for their experiments. Together they eventually amassed 21,000 books, more than in most European universities, and they each had separate rooms packed with equipment. Du Châtelet took over the great hall, where she tested Newton’s theories with wooden balls swinging from the rafters and metal apparatus forged from the nearby iron mines. She also had her own study, where the desk groaned under instruments, books and mathematical manuscripts. She decorated her chambers in blue and yellow, even coordinating the dog’s basket into her colour scheme. The lavish fittings included several large mirrors, a huge walk-in wardrobe to accommodate her clothes, and a triple-locked jewellery closet. A secret passage led to Voltaire’s suite of rooms – a small oak-panelled antechamber and a long gallery overlooking the gardens. In addition to his valuable ornaments, three pieces of furniture were placed against the end wall: a bookcase, a glass-fronted cupboard packed with scientific instruments and a heating stove disguised as a large statue of Love.
Like many couples, during their fifteen years at Cirey they developed their own daily schedules, so that they could spend time apart as well as together. Du Châtelet liked to rise at dawn while Voltaire was asleep, so that she could organise the household, deal with correspondence and see her children. Then she went upstairs to work, reportedly elaborately dressed and coiffed, until dinner – a very movable feast, as hungry guests discovered. Dinners were long, extravagant affairs, served through trapdoors so that the servants would not interrupt the intense debates.
Sometimes du Châtelet and Voltaire studied together, observing each other’s experiments, discussing their latest ideas and annotating each other’s manuscripts. But du Châtelet also liked to work alone in her room on her private projects. One summer Voltaire became absorbed in research for an essay competition about the nature of fire. After du Châtelet carried out her own investigations, she decided that Voltaire – who relied heavily on Aristotle – had reached the wrong conclusions. Only a month before the closing date, she decided to compete herself, but kept her plans secret in order not to annoy him. After many sleepless nights, she submitted her entry – an erudite memoir of 139 pages. She felt that since her essay would be submitted without her name, it stood a better chance of being fairly judged. ‘I wanted to test my strength under the cover of anonymity,’ she wrote to Maupertuis.16
Neither Voltaire nor du Châtelet won the prize (which went to some Cartesians), but he later persuaded the Academy of Sciences to publish both their entries – the poet/lover combination made good publicity. Knowing that her essay would be appearing under her own name, du Châtelet meticulously checked the details to protect her reputation, and became engaged in a head-on confrontation with one of the Academy’s leading natural philosophers, who took her arguments seriously enough to oppose her publicly in print.
Du Châtelet and Voltaire welcomed visitors, but did not permit them to disrupt the daily schedule of study. Some of the intimate details of life at Cirey have survived in the letters of gossipy correspondents, although they can hardly be totally reliable – it must have been enormously tempting to twist a relatively innocuous event into something more dramatic for entertaining a distant reader. Her husband was often away at war, but he soon adapted himself to the unconventional ménage, coming to stay and also publicising their manuscripts. In addition, to compensate for being excluded from more orthodox academic circles, du Châtelet invited France’s leading scholars to join her intellectual court. Several eminent mathematicians and natural philosophers came to Cirey, including a hired tutor who stayed for two years, Maupertuis (who became great friends with Voltaire) and Clairaut, who was heralded as France’s new Newton.
* * *
During their second summer at Cirey, du Châtelet read Italian classics and studied natural philosophy with Voltaire. By the time of Algarotti’s visit, Voltaire recalled later, ‘he found her sufficiently skilled in his own language as well as familiar with the works of Newton to give him some very excellent information from which he profited’. Algarotti was impressed by Newton. ‘Who would ever have believed,’ he remarked, ‘that England, which was reputed a country of dolts, should so excel and give laws in the sciences?’ Algarotti had studied at Bologna, a progressive city where women’s education was encouraged. Even one of the university’s professors, an expert on Newton, was a woman – Laura Bassi, the envy of learned women all over Europe. By the standards of the time, Catholic Italy permitted girls to study a wide range of subjects. Bassi was afforded the status denied to du Châtelet, and other ambitious Italian girls were following her example by taking courses in natural philosophy.17
Algarotti completed his Newtonianism for the Ladies while he was staying at Cirey, and it first appeared, in Italian, in 1737. Like many educational books of that period, it is written as a dialogue between the author-teacher and the reader-pupil. Algarotti portrays himself instructing an imaginary Marquise who was glamorous, flirtatious and not very bright. The text is packed with sexual innuendoes and references to female vanity. Taken at face value, this slim book seems a laudable attempt to extend scientific education towards women. Viewed more sceptically, it undermines female equality by reinforcing the notion that women are inherently incapable of serious thought. Mathematics, thought Algarotti, was certainly beyond their capacity. The frontispiece (Figure 17) showed the refined young man – a swan, sneered Voltaire – with a real-life Marquise, his hostess and Newtonian colleague, du Châtelet. Before publication, she had been thrilled; afterwards, she was angry at being linked with his flighty heroine. ‘His book is frivolous,’ she fumed, and accused him of aiming at the boudoir market.18
The following year, 1738, a second Cirey book on Newton appeared, this time in French: Elements of Newton’s Philosophy, with Voltaire’s name on the title-page. Voltaire had smuggled it out to Holland for publication, but had found time to insert some last-minute jibes about his Italian rival’s flowery style and to write a long poem explicitly addressing the book to a non-imaginary Marquise – Émilie du Châtelet. Far more solid than Algarotti’s superficial sketch, this Newton was well illustrated and clearly explained the basic principles of Newton’s discoveries in mathematical astronomy and optics. For the first time, Newtonian ideas were accessible to a wide range of French people, and this book was a huge success.
The publication of Elements is often seen as a turning point in French science. According to many older accounts, Voltaire single-handedly convinced the nation of Newton’s superiority to Descartes. More convincing versions describe a slower rate of change and point out that Voltaire seized a particularly opportune moment to publish. This was exactly the right time to market an introductory text because French people were already half-converted to Newtonianism. Maupertuis had been promoting Newton (and himself) by sending back dramatic reports of his exploits in Lapland, where he led an expedition to settle a crucial question about the shape of the Earth. According to Descartes, it was elongated like a lemon; according to Newton, it was slightly flattened at the poles. Maupertuis, just as adept at self-publicity as Voltaire, converted the ambiguous results into an outstanding victory for Newton – and also for Maupertuis, who became France’s new scientific hero.19
As another blow to the traditional story, although Elements of Newton’s Philosophy came out under Voltaire’s name, it was a joint production. The frontispiece (Figure 16) shows Voltaire sporting his poet’s laurel wreath, assiduously transcribing the words of his female muse – ‘Minerva dictated and I wrote,’ he told a friend. Du Châtelet is holding a mirror, a doubly appropriate symbol that immediately identifies her as the goddess of truth, but also alludes to her interest in her appearance. To reinforce the message, Voltaire included a foreword that made his debt to her clear: ‘The solid study that you have made of several new truths and the fruit of considerable work, are what I am offering to the Public for your glory.’
It is impossible to reconstruct their individual contributions precisely, especially as the book was extensively edited in Holland, but du Châtelet’s involvement was substantial. And it was she, not he, who sent an abstract to one of France’s top scientific journals. To prepare himself, Voltaire plunged into Newton’s Opticks – unlike du Châtelet, he could not cope with the complicated mathematics of Newton’s Principia. As Voltaire bought himself more and more equipment – a telescope, an air-pump, thermometers and barometers – he confided to a friend that ‘in all of this, Madame du Châtelet is my guide and my oracle’. Just as Voltaire’s private letters refer to their collaborative study of the ‘Émilienne philosophy’, so too he was not embarrassed to declare his intellectual allegiance publicly. ‘Let me stand next to you,’ proclaims his florid verse preface, ‘and show Truth to the French nation.’20
Early 1737: at last du Châtelet had some time to think. The house renovation work was more or less complete, Algarotti had been and gone, Voltaire no longer needed her help with their Newton. While they studied together, she had been carving out her own position, and now she set off in a new direction. Voltaire, who hero-worshipped Newton and was weaker than her mathematically, often accepted what other scholars told him, whereas du Châtelet was an astute critic who formulated her own ideas. When a new edition of Elements of Newton’s Philosophy came out ten years later, Voltaire saluted her: ‘I used to teach myself with you. But now you have flown up where I can no longer follow.’ Du Châtelet’s own two scholarly books about Newton grappled with the philosophical relationships between the Cartesian, Leibnizian and Newtonian systems.21
Unlike Voltaire, du Châtelet believed that good science demands metaphysical foundations. She was not satisfied with knowing how the universe works: she wanted a rational explanation of why it works. The nature of matter, the role of God, good and evil – these were the sort of issues that du Châtelet worried about. She accused Descartes of providing answers that were wrong; she criticised Newton and Voltaire for avoiding the questions. Newtonian science, she pointed out, purports to be based solely on experimental observations, yet inevitably entails metaphysical assumptions about the existence of scientific laws.22
For about a year and a half she prepared a new manuscript, Foundations of Physics, in which she tried to integrate the ideas of Descartes, Leibniz and Newton (see Figure 12). She wrote in complete secrecy, trapped in a dilemma. She desperately needed constructive criticism, but risked painful mockery by revealing that she, a woman, was engaged in such innovative work. Many learned women experienced similar conflicts. Almost a hundred years later, the English mathematical physicist Mary Somerville was working on a mirror-image project – elucidating the cosmological ideas of ‘the French Newton’, Pierre Laplace, for an English audience. ‘I hid my papers as soon as the bell announced a visitor,’ Somerville confessed, ‘lest anyone should discover my secret.’ Even close friends remained unaware that she was producing a book that would modernise university teaching and make her famous.23
At the last moment, du Châtelet panicked. Several chapters had already been printed, but she withdrew the book, embarked on an intensive course of mathematics with a private tutor and rewrote large sections to incorporate Leibniz’s views. Perhaps – it seems a likely step – she had decided to confide in Maupertuis, who was fresh back from Lapland. But now she faced another nightmare: rumours spread that she was plagiarising her hired tutor’s work. Vainly hoping to quell the gossip, she rushed into print.
In welding together three conflicting systems, du Châtelet suggested a novel yet welcome approach. Helped by the Newton that du Châtelet and Voltaire had worked on together, Newtonian ideas were spreading through Europe, but there were some fundamental clashes between the ideas of Europe’s three eminent natural philosophers. In the universes of Newton and Descartes, mechanical forces operate on passive matter. By incorporating Leibnizian ideas about active substances, du Châtelet helped to forge a new version of Newtonian physics that resolved the problems of describing force and movement. But not everyone accepted this Leibnizian intrusion, and she became involved in a long-running international controversy that eventually resulted in new physical laws of energy. Her arguments were known and discussed: her public dispute with the eminent Secretary of the Paris Academy was analysed by Kant in his first published work.
Du Châtelet’s Foundations of Physics was well received. It was reviewed in prestigious journals, and Maupertuis promoted it – and her – lavishly, writing that her book would have done credit to a leading member of Europe’s prestigious academies. Unlike some commentators, he complimented her extraordinary achievement as a woman, yet without patronising her. The author’s brilliance, he observed, is surpassed only by her modesty, since she chose to publish anonymously. After her identity had been revealed, du Châtelet was elected to the Bologna Academy – but never to the Paris Academy of Sciences.
In the years after Foundations of Physics finally appeared, du Châtelet continued to experiment and to study, but she kept getting side-tracked. Her days were not entirely under her own control. She spent months on end in Brussels, overseeing a protracted legal case about her husband’s property, and moaned about the time she devoted to obtaining a military commission for her son. Voltaire was a time-consuming partner who demanded editorial assistance as well as emotional care, and they spent a lot of time travelling, sometimes to escape the police. Although she pestered her aristocratic friends in Paris to back him, Voltaire’s defiantly anti-establishment writing antagonised many people. And as well as running several households, du Châtelet got swept up in other exciting activities – dinner parties, gambling, amateur theatricals.
Like many women, du Châtelet turned to translation, intellectual work that tolerates frequent interruptions. She had already translated literary works, and now she was absorbed in natural philosophy. Good translations are vital for spreading new ideas, and modern international science could not have developed without them. For du Châtelet, translation meant more than just converting words into another language. She believed she should create her own version of a text, one that incorporated her own ideas as well as those of the original author. Newton had written his Principia in Latin, and had used complicated arguments; even the English version had errors. Du Châtelet aimed to give academics a scholarly study that interpreted Newton’s ideas as well as translating his words into Europe’s international language – French.24
Her work may have been intermittent, but it was thorough. To start with, she studied Newton’s three different editions of the Principia, as well as his further attempt (published separately) to explain how his mathematics described the cosmos. Then there were all the commentaries, by English and Dutch disciples as well as by critics. And on top of that, French and Swiss mathematicians had developed his theories algebraically. She corresponded with experts, especially two who were also Cirey visitors: François Jacquier, a Jesuit priest and physics professor who lived in a monk’s cell decorated with a trompe l’œil portrait of Newton; and Clairaut, her long-standing mathematics tutor, who had travelled to Lapland with Maupertuis and was now France’s leading authority on Newtonian astronomy.25
By 1745, she had started to translate, snatching the early hours of the morning to work in peace. Clairaut was so impressed by the accuracy of her thought and the clarity of her language that he recommended her work to the royal censors, whose approval was necessary for all books published in France. But the whole project got delayed as she immersed herself deeper and deeper. Du Châtelet decided to undertake not only the literal translation of the text itself, but also three further types of translation. For newcomers, she converted the complex mathematics into elegant prose, supplemented by her own examples. Next, she turned to calculus, translating Newton’s geometry into the new continental algebra. And finally, she summarised recent mathematical research and experimental vindications of Newton’s theories.
Like Maupertuis, Clairaut was adept at self-promotion. In 1747, he made a dramatic announcement to the Paris Academy – Newton’s law of gravitation was wrong! Newton had undertaken the complicated calculations involved in working out how the moon moves under the simultaneous tug of the Earth and the sun. This was, he said, the only problem that ever gave him a headache. Now, twenty years after Newton’s death, Clairaut claimed that the moon was not where it should be according to Newton’s physics. While everyone argued, Clairaut spent eighteenth months checking his figures, and then emerged theatrically to declare that Newton was right after all. Both Clairaut and Newton gained publicity from this manoeuvre.
Meanwhile, a domestic drama was being played out at Cirey. To her surprise, du Châtelet discovered that she was pregnant. Then aged forty-three, she was an elderly woman by contemporary standards. Although Voltaire was not the father, he helped her deceive du Châtelet’s husband into thinking that the baby was legitimate. Plagued by gloomy premonitions, du Châtelet intensified her work schedule, working eighteen hours a day to finish in time. And she did finish, with a couple of weeks to spare. But her predictions of mortality were correct. A few days after her daughter was born, she fell ill. On her final day, 10 September 1749, du Châtelet asked for her Newton commentary and recorded the date on it. Then, lapsing into a coma, she died.
As obituarists vied to produce witty digs disguised inside flowery compliments, du Châtelet’s manuscript mysteriously vanished. Nevertheless, someone evidently had a talent for timing, because ten years later her Principia was – like the earlier Elements of Newton’s Philosophy – published at a new peak of public interest in Newton. Clairaut had just helped to achieve yet another victory for Newtonian astronomy. For decades, French astronomers had been arguing about Edmond Halley’s forecast that the 1682 comet would return in 1758–9. Using the latest mathematical techniques, Clairaut recalculated the date, but made his propaganda more effective by refusing to divulge his methods. Everyone waited to see if he was right.
And he was: the comet arrived on schedule, the newspapers heralded Clairaut as the new Newton, and du Châtelet’s sparkling new translation appeared in the book shops. A publicity machine for France’s ‘illustrious female scholar’ moved into action. ‘The public has been waiting impatiently for years,’ enthused one journal, insisting that the unexplained delay made the book ‘even more stunning, by contributing to philosophy’s moment of triumph’.26 This advertisement of Newton’s victory was overconfident. Extraordinary as it now seems, there were fierce debates in France during the 1770s about a French experiment that claimed to disprove gravity: objects were apparently getting heavier rather than lighter as they were moved up a mountain away from the centre of the Earth. Although this was an elaborate hoax, its success illustrates how powerfully and for how long anti-Newtonian lobbies operated in France.27
It took the best part of a century for Newton to displace Descartes and become France’s new God of Reason. Du Châtelet played a vital role, because she explained Newton’s ideas with unsurpassed clarity, and also made them more palatable by integrating them with other philosophical systems. The Encyclopédie, itself packed with propaganda for Newton, praised seven writers who had made Newtonianism easier to understand. Only one of them lived in France – Émilie du Châtelet.