Writing in 1751, Voltaire celebrated and yearned for the vibrancy of the previous decades when Europe had seemingly experienced an intellectual renaissance. This golden age, the ‘Age of Louis XIV’, as he came to term it in his eponymous historical work (the Siècle de Louis XIV), had surpassed all previous centuries in terms of the various discoveries and institutions it had helped foster in the sciences and the arts. These, unlike political matters, would stand the test of time and forever attest to the capacities of human reason. During this period, Voltaire wrote, ‘the human mind made the greatest progress’ , ‘[acquiring] throughout Europe greater lights than in all the ages that preceded it’, mainly through the tireless and often anonymous labours of several geniuses who, spread across Europe, ‘[had] enlightened and comforted the world during the wars that spread desolation through it’. This ‘Republic of Letters’ had gradually imposed itself throughout Europe, oblivious to the religious and political schisms that had torn it apart: ‘The arts and sciences, all of them thus received mutual assistance from each other, and the academies helped to form this republic [...] the truly learned of every denomination have strengthened the band of this great society of geniuses, which is universally diffused, and everywhere independent’. Even though this network’s influence had considerably waned in Voltaire’s time, it had subsisted over the years bringing comfort to mankind over the ‘evils which ambition and politics scatter through the world’.
Ironically enough for the future author of Candide (1759) and creator of the infamous character Dr Pangloss, it was none other than the German thinker Gottfried Wilhelm Leibniz (1646-1716), ‘perhaps a man of the most universal learning in Europe’, who had animated the universal network of communication that underpinned the intellectual revolution that had taken place decades earlier. Indeed, through Leibniz’s intervention, ‘there never was a more universal correspondence kept between philosophers than at this period’. Already as a young man, steadily expanding his network of correspondents, Leibniz prided himself on having entered into literary commerce with many of the most learned scholars in Europe. In a letter of August 1671 to Peter Lambeck, historian and librarian at the Imperial Court in Vienna, he highlights the wide geographical distribution of his network, listing the most notable names according to country – Athanasius Kircher and Francesco de Lana in Italy, Otto von Guericke and Hermann Conring in Germany, the royal librarian Pierre de Carcavi, Louis Ferrand, and others in France, Henry Oldenburg and John Wallis in England, Johann Georg Graevius and Lambert van Velthuysen in the Low Countries, and so on. Leibniz chose his correspondents purposefully. By establishing an epistolary commerce with the secretary of the Royal Society, Henry Oldenburg, in 1670, at an early stage in his career, Leibniz sought entry into the leading scientific institution of his day. Moreover, he was successful in this enterprise, producing within a year a new physical hypothesis dealing with many of the concerns of the London virtuosi at the time. In the case of Antoine Arnauld, he sought to subject his philosophical ideas to the scrutiny and criticism of one of France’s most astute thinkers who was also a leading Catholic theologian. Since Leibniz was, alongside his various other projects, seeking to bring about Christian reconciliation, he was additionally able to test the acceptability of his irenic theses to the Roman Catholic Church through his discourse with Arnauld. As with Arnauld, Leibniz first met the scholar Simon Foucher during his momentous stay in Paris from 1672 to 1676. He valued the sagacity Foucher had displayed in his opposition to Malebranche’s philosophy and used the medium of their correspondence to air some of his own fundamental metaphysical ideas. Foucher for his part kept Leibniz, now living in provincial Hanover, abreast of intellectual news from Paris and in particular of members of his French circle of friends – scholars such as the churchman Pierre Daniel Huet, the editor of the Journal des savants, Jean Gallois, and Melchisédech Thévenot, an important figure in the foundation of the Académie royale des Sciences. Already in his new physical hypothesis, Leibniz had declared the improvement of the human condition to be ‘the sole aim of philosophy’. His groundbreaking work in diverse fields such as mathematics (where alongside Newton he was the inventor of the calculus), logic, engineering, geology, and the biological sciences, and his promotion of the need for scientific academies in Berlin, Dresden, Vienna, and St Petersburg in which theoretical investigations could be combined with practical considerations, all fall within the overall compass of improving life. The Berlin Academy bears to this day the Leibnizian motto ‘Theoria cum praxi’.
While Voltaire’s scathing criticism of his philosophy, particularly the doctrine put forward in the Théodicée that this is ‘the best of all possible worlds’, appeared difficult to answer against the backdrop of natural disasters such as the Lisbon earthquake (1755), much of Leibniz’s scientific and technological thought has been of tremendous prescience and significance – although sometimes only identified as such comparatively recently. His work on a calculating machine based on the binary system anticipated our modern day computers, his ideas on insurance and fiscal policy were designed to ensure a greater degree of protection and justice for the population, mathematical papers on determinants and combinatorics were years ahead of their time. And as his extensive surviving papers and letters are steadily edited in the critical Academy Edition, more wonders of this nature are expected. – Audrey Borowski and Philip Beeley  All quotations are from the Siècle de Louis XIV, chapter 34, ‘Des Beaux-Arts en Europe du temps de Louis XIV’. Translations are from The Works of M. de Voltaire. Translated from the French, by T. Smollett, T. Francklin and others, 36 vol. (London, 1761-1765), vol.9 (1761), p.152-62.