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Brief Lives

Émilie du Châtelet (1706-1749)

Andrea Reichenberger presents a fulcrum of the European Enlightenment.

Gabrielle Émilie le Tonnelier de Breteuil, Marquise du Châtelet, was born on 17 December 1706 in Paris, the only girl amongst six children. Her mother was Gabrielle Anne de Froullay, Baronne de Breteuil. Her father was Louis Nicolas le Tonnelier de Breteuil, a member of the lesser nobility. At the time of Émilie’s birth, her father held the position of the Principal Secretary and Introducer of Ambassadors to King Louis XIV. This position provided her at a young age with access to France’s aristocratic and intellectual elites.

Emilie, Marquise du Châtelet

On 12 June 1725, du Châtelet married the Marquis Florent-Claude du Chastellet-Lomont, a military man who was made governor of Semur-en-Auxois in Burgundy. Like many marriages among the nobility, theirs was arranged. Du Châtelet was eighteen at the time, her husband thirty-four. After bearing three children, the Marquise du Châtelet reached an agreement with her husband to live separate lives. So in 1733, aged twenty-six, du Châtelet resumed her studies, resourcefully seeking some of France’s best tutors and scholars to mentor her in mathematics. Initially, she contacted Pierre Louis de Maupertuis, a member of the Academy of Sciences, and Alexis Claude Clairaut, a famous mathematician, credited with Clairaut’s equation, Clairaut’s theorem, and indeed Clairaut’s relation. Perhaps the most important personal relationship – and in any case a very tense one – was with Voltaire (François-Marie Arouet), a French Enlightenment writer, historian, and philosopher well-known for his criticism of Catholicism and his plea for freedom of speech, freedom of religion, and separation of church and state.

Maupertuis and Voltaire were two of the most important influences in du Châtelet’s life. Maupertuis (1698-1759) became director of the Académie Royale des Sciences and the first President of the Prussian Academy of Science. Voltaire (1694-1778) gained fame for criticizing the abuses of absolutism and feudal rule as well as the ideological monopoly of the Catholic Church. To help him avoid arrest after the publication of his anti-establishment Lettres Philosophiques (1734), du Châtelet invited Voltaire to take refuge in her country house at Cirey in Haute-Marne. There, Voltaire became her long-time collaborator. For fifteen years, the pair lived together, sharing their passion for science, setting up a laboratory and performing experiments in optics. In addition, they built up a collection of twenty-one thousand books, which was larger than the libraries of most European universities.

The years du Châtelet spent with Voltaire at Cirey were some of the most productive years of her life. In 1737, the Académie des Sciences in Paris set the topic for their Grand Prix to be on the nature of fire and its propagation. Both Voltaire and du Châtelet submitted entries. Although neither of them won (the prize was won by Leonard Euler), both essays received honourable mention and were published. Du Châtelet thus became the first woman to have a scientific paper published by the Academy.

At that time both Voltaire and du Châtelet were working on Newton’s ‘natural philosophy’. Voltaire’s Eléments de la Philosophie de Newton (1738) contributed to the spread of Newton’s ideas on gravity, optics, and light in France, making them more understandable and accessible to the lay reader. Du Châtelet’s Institutions de Physique, first published in 1740, was more critical towards Newton’s doctrines, confronting them with Leibniz’s theory on living forces, and further alternative approaches to physical phenomena offered by Leibniz.

Du Châtelet’s major work was a translation of Newton’s Principia. She used the third Latin edition of Philosophiae Naturalis Principia Mathematica, which had been published in London in 1726 (the so-called ‘Pemberton edition’). She began work on the translation in 1745, and the Royal Privilege for printing it was granted to her in the following year. A part was published in 1756, under the direction of Clairaut, with a preface written by Voltaire. The complete work appeared in 1759, and was for many years the only translation of the Principia into French. Du Châtelet also added a commentary to the translation. The first part tells the history of astronomical models back to the Babylonians and Pythagoras, up to Newton’s death. The second part presents algebraic equivalents for disputed and difficult sections of the Principia; for example, planetary orbits under the force of attraction, or the refraction of light based on the principles of attraction.

Du Châtelet did not live to see the publication of her magnum opus. On the night of 4 September 1749 she gave birth to a daughter, Stanislas-Adélaïde (the father was the French poet and writer Jean François de Saint-Lambert), but died on 10 September at Château de Lunéville from a pulmonary embolism. She was 42. Her daughter died twenty months later.

Émilie du Châtelet’s Way To & Beyond Newton

In the fall of 1735, the Italian scholar Francesco Algarotti, who was preparing a book about Newton, visited Cirey. As early as 1728, he had carefully replicated several of Newton’s optical experiments at the University of Bologna. In Cirey, Algarotti finished his popular scientific work Il Newtonianismo per le Dame (Newtonianism For Ladies), first published in Venice in 1737. This bestseller, translated into several languages, made Algarotti a European celebrity and a representative for what became in the eighteenth century a vast Newtonian industry. Under Émilie and Voltaire, Cirey became a center of this intellectual and philosophical movement.

Partly inspired by Algarotti’s visit, the Marquise and Voltaire began to study Newton’s optical and gravitational theories intensively. By 1736, Voltaire, in close exchange with du Châtelet, was working on his book Éléments de la Philosophie de Newton, but at the same time du Châtelet was critically distancing herself from Voltaire’s reading of Newton. Although her anonymous review Lettre sur les Éléments de la Philosophie de Newton in the Journal des Savants (1738) helped to support Voltaire’s publication, she was working on a profound transformation of Newtonian science. Two years later, she published Institutions de Physique, first anonymously (1740), then under her name (1742). Mainly positive reviews of this book appeared in English, French, Italian, and German during her lifetime. The Institutions covered a wide range of philosophical topics, from the basic principles of reasoning and our knowledge of God, to questions concerning the proper views of space, time, matter, and the laws of nature. The work provides long discussions of the latest research regarding gravity, including presentations of Galileo’s and Huygen’s results, as well as of Newton’s more comprehensive work.

Scholars have often suggested that du Châtelet attempted to integrate the Cartesian, Newtonian, and Leibnizian philosophies together, but this interpretation is not beyond dispute. In fact, du Châtelet’s Institutions sought to reconcile complex ideas from many leading thinkers of the time, among them the English physicist James Jurin, the Swiss mathematician and physicist Daniel Bernoulli, the Dutch botanist, chemist and natural philosopher Herman Boerhaave, his compatriot Willem Gravesande, and the German polymath and philosopher Christian Wolff. Du Châtelet based her approach on a critique of Descartes and Newton, highlighting the importance and proper use of hypotheses, thereby establishing a new methodological basis for searching for truth in sciences. She argued that the common tools connecting the Cartesian, Newtonian, and Leibnizian philosophies and sciences were demonstrations, performed in the style of Euclid’s geometrical demonstrations.

From Controversies to Innovations

With her translations and publications, du Châtelet came to play a leading role in Enlightenment thought and discourse on science, based on empiricism and rational thought, and driven by the ideal of scientific advancement and intellectual progress.

Scientific controversies and prize essay questions had become central to this discourse, and Du Châtelet was one of the few women who actively participated in them. While doing so she paved the way for fundamental new insights, especially in physics: from the nature and propagation of fire to what we call today infrared radiation; from the controversy about the ‘true quantity of motion’, to energy conservation; and so on.

As I mentioned, her major work was a translation of Newton’s Principia. A part was published in 1756, seven years after her death, under the direction of Clairaut, with a Preface written by Voltaire. The complete work appeared in 1759. Other work undertaken by du Châtelet was a translation of Mandeville’s La Fable des Abeilles (1714/1723). She omitted sections, added material, and wrote a Preface. She further reflected on happiness and liberty, and wrote a Grammaire Raisonnée. Du Châtelet is the only female French author of a work included in the corpus of ‘clandestine philosophical literature’ – a genre that flourished in the eighteenth century that included subversive political pamphlets, satires of court life or of the nobility, and forbidden religious texts. In an anonymous, and very long, tract concerning the Bible, Mme du Châtelet questions Biblical doctrines from Genesis to Revelation, reading the Old and New Testaments from the ethical, philosophical and scientific views of a Voltaire-influenced scholar who saw in the Church a formidable apparatus of coercion. It is both the hidden face of a great scholar of the Enlightenment, and an original contribution to the growing anti-ecclesiastical tide of the eighteenth century.

Du Châtelet’s Influence on the German Enlightenment

The scientific and intellectual networks of the eighteenth century were interconnected in complex and multifaceted ways. This can be seen from the impact of Du Châtelet’s works on the German Enlightenment. One of the first academics to read du Châtelet’s Institutions de Physique was the Swiss mathematician Leonhard Euler (1707-1783), with whom she corresponded. Translations of du Châtelet’s works played a paradigmatic role in the dissemination of ideas across linguistic borders. In 1741, the German translator, essayist and writer Gottsched translated du Châtelet’s dispute with the Cartesian Jean Jacques d’Ortous de Mairan, a leading member of the Académie Royale des Sciences. Du Châtelet argued in favor of Leibniz’s ‘living force’ and its measurement, which is obtained from the integral taken along the path a body travels while acted upon by a force. As was shown by the Swiss mathematician Daniel Bernoulli in 1724, this measurement represents the gain or loss of living force in terms of ½ mv². In other words, it’s equivalent to what we now call ‘kinetic energy’.

In 1743, Wolf Balthasar Adolph von Steinwehr translated du Châtelet’s Institutions Physiques. Steinwehr was an extraordinary professor of philosophy at the University of Göttingen, and the editor of the German journal Neue Zeitungen von Gelehrten Sachen (The New Journal of Things Learnt). Steinwehr’s German translation became a hot topic in German newspapers and journals. In the same year, the mathematician Abraham Gotthelf Kästner published an article entitled Letter on Empty Space in Return of the Marquise du Chatelet’s Philosophy of Nature. Kästner stated that du Châtelet was ‘too little British and too much German’ – meaning that she followed Leibniz and German philosopher Christian Wolff too closely, and Newton too little, by (correctly) rejecting absolute empty space. An anonymous author defended du Châtelet in a later issue. Kästner replied, mocking Leibnizians as ghost-seers, because according to Leibniz’s monad theory, atoms should be understood as ‘soul-like entities’. This led to an on-going debate, in the journal and beyond it. For instance, in 1745, the Berlin Academy of Sciences opened a prize essay competition entitled L’examen de l’hypothese des Monades. The competition inadvertently gained fame because Euler, as one of the members of the selection committee, made the faux pas of publishing an anonymous pamphlet in which he attacked the doctrine of monads. An examination of du Châtelet’s ideas can also be found in Immanuel Kant’s early work, Thoughts on the True Estimation of Living Forces (1747/1749).

Influence Beyond the German Enlightenment

Du Châtelet was recognized and discussed not only in Germany, but also in France, Italy, the Netherlands, and even further afield. For example, Ruđer Josip Bošković (1711-1787), a Croatian scientist and philosopher, was influenced by du Châtelet when he became engaged in the study of Newton’s theories. In his Philosophiae Naturalis Theoria (1748), Bošković proposed the idea of an omniscient spirit which, based on knowledge of Newton’s laws and knowledge of all of the forces and initial positions at one moment, would have complete knowledge of the past and the future. Following essentially identical postulates, the French scientist Pierre Simon Laplace (1749-1827) presented the classical formulation of the principle of determinism nearly half a century later, in 1814. This spirit or ‘intelligent entity’ was later dubbed Laplace’s Demon, although the demon’s origin in fact dates back to du Châtelet’s Leibniz interpretation of the éternel Géomètre.

Another example: Eugenios Voulgaris, one of the major Greek thinkers of the Enlightenment, was influenced by the German reception of Mme du Châtelet’s Institutions Physiques. Voulgaris played an important role for the re-appearance of metaphysics in natural philosophy during the Greek Enlightenment.

Last, but not least, Émilie du Châtelet’s conception of the role of hypotheses within an architecture of knowledge based on fundamental principles, not only challenged Newton’s ‘hypotheses non fingo’ (his claim that ‘I do not make hypotheses’), but inspired Abbé de Condillac’s, Georges-Louis Leclerc’s, Comte de Buffon’s and Albrecht Haller’s fruitful reflections on the hypothetico-deductive method.

Andrea Reichenberger is Research Group Leader at the Department of Mathematics, University of Siegen (Germany). Her research activities focus on women’s contributions to logic, mathematics, and computer science. Her doctoral dissertation on Émilie du Châtelet was published by Springer in 2016.