Combined with the "questioning everything" he was either a blast at parties or an insufferable bore.
From the New York Review of Books: Lynn Hunt
March 7, 2019 Issue
...MUCH MOREDiderot and the Art of Thinking FreelyThe most radical thinker of the eighteenth century, Denis Diderot (1713–1784), is not exactly a forgotten man, though he has been long overshadowed by his contemporaries Voltaire and Jean-Jacques Rousseau. After the French Revolution of 1789, the French right routinely blamed every ill of modern life on Voltaire and Rousseau. The expressions “It’s the fault of Voltaire” and “It’s the fault of Rousseau” became so familiar that Victor Hugo could satirize them in a ditty sung by the urchin Gavroche in Les Misérables (1862): “Joy is my character; ’tis the fault of Voltaire; Misery is my trousseau; ’tis the fault of Rousseau.” Voltaire and Rousseau were among the first to be buried in the French Pantheon of the nation’s heroes; Diderot has yet to be, despite a concerted campaign leading up to the three-hundredth anniversary of his birth in 2013.
by Andrew S. Curran
Other Press, 520 pp., $28.95
Catherine and Diderot: The Empress, the Philosopher, and the Fate of the Enlightenment 
by Robert Zaretsky
Harvard University Press, 258 pp., $27.95
Diderot was simultaneously too much a man of his time and too much ahead of his time. He devoted the best years of his life to organizing, editing, and writing many of the 74,000 articles of the Encyclopedia (1751–1772), a vast compendium of knowledge amounting to seventeen volumes of text and eleven volumes of plates, and laced with acerbic commentary that alarmed the authorities for attacking religion and subverting government. Known mainly to scholars today, at the time the project served as a thrilling treasury of Enlightenment ideas, if you knew where to find the nuggets hidden under the most unlikely headings. In the article “Nonetheless, However, Nevertheless, Notwithstanding,” for example, Diderot argued that even anti-Christian—i.e., atheist—writers could “nonetheless” be good parents, good friends, and good citizens. Since many articles were unsigned and the known contributors came from every corner of French life, no one could be sure what other ideas were Diderot’s.
As if that exhausting labor were not enough, Diderot anonymously contributed heaps of pages to another sprawling but influential work, this one on European colonialism. The History of the Two Indies appeared under the name of his friend the ex-Jesuit Guillaume Raynal. Diderot’s involvement in turning the second and third editions (1774 and 1780) into incendiary denunciations of European colonialism and the slave trade remained largely unknown before the second half of the twentieth century; the papers he left to his daughter were only inventoried in 1951, thanks to the work of Herbert Dieckmann, a German émigré professor then at Harvard, and scholars are still sorting out what came from Diderot’s pen.
As a man of his time, Diderot loved company and he loved Paris, the very place that Voltaire and Rousseau were always fleeing. His connection, unlike theirs, was not with public opinion but with the people he could talk to: his wife and daughter, his lovers, his countless friends, and, eventually, one ruling monarch in faraway Russia, Catherine the Great. In an age of conversation, he stood out for his volubility. When excited, he could hardly contain himself and would frequently grab his interlocutor’s arm or leg to drive home his point. Catherine found it helpful to keep a table between them during their Saint Petersburg tête-à-têtes. A passionate enthusiast about a staggering range of topics, from science and metaphysics to painting and novels, Diderot tirelessly promoted his colleagues but proved too gullible. For four years he gave work to a penniless copyist who turned out to be a spy planted by the Paris chief of police, a friend of Diderot’s from his school days. In the worst of all betrayals, the Encyclopedia’s publisher secretly bowdlerized the final volumes in order to forestall the censors, leaving its furious editor with no option other than nursing his wounds in private.
Diderot was far from being an intellectual magpie who simply scavenged bits to build a nest out of other people’s ideas. He took seriously his own pronouncement in the article “Encyclopedia” in volume 5:I have said that an Encyclopedia could only be attempted in a philosophical century; and I said it because this work requires a more courageous spirit than can commonly be found in centuries of pusillanimous taste. We must examine everything, stir up everything without exception and without restraint.When he roused the authorities with his first novel (The Indiscreet Jewels, 1748, the “jewels” being vaginas that talked when bidden by a magic ring) and a deliberately provocative philosophical tract (Letter on the Blind, 1749), which even Voltaire found too boldly atheistic, the thirty-five-year-old transplant from the provinces was sent to prison by royal command. The king did not need to specify the charge or set the term. Diderot could conceivably have languished there forever....
Anatomy of a Blogger, after Diderot’s Encyclopédie, ou dictionnaire
raisonné
des sciences, des arts et des métiers by Mike Licht via flickr
