Pondering Diderot’s Encyclopedia Never Ceases to Blow My Mind

In the fall of 2011, I signed up for a French literature course at Eastern Michigan University. I loved the class and am indebted to our professor, Benjamin Palmer, who improved my understanding of great literature and its relationship to history. I enthusiastically enrolled in a second semester that winter and again enjoyed every minute. Throughout that academic year, however, nothing impacted me more than my firsthand encounter with an 18th-century copy of Diderot’s Encyclopédie.

The story of how Denis Diderot produced this masterwork, a 28-volume encyclopedia containing more than 76,000 entries, is mind-boggling. In 1746, he and the French mathematician, Jean-Baptiste d’Alembert, set out to create an encyclopedia that would describe and illustrate all available human knowledge. D’Alembert is often listed as a co-author but there is no doubt that without Diderot’s fanatical devotion, the project would have never come together.

In fact, there were many contributors but Diderot was chief among them, producing more than 7,000 articles. He also acted as editor, soliciting and proofreading thousands of contributions, working with engravers who created etchings of illustrated submissions, updating pages when new discoveries were made, and creating a master index of all articles and artwork. When completed, the Encyclopédie contained 17 volumes of articles and 11 volumes of illustrations.

It’s difficult to imagine the coordination and concentration needed to complete such an immense undertaking. Added to the complexity was the perpetual overhead of remaining in the good graces of a hypersensitive king and the even touchier Catholic church. Both of these powerful institutions had strong reservations about disseminating knowledge to the average citizen—Diderot’s ultimate target audience.

Indeed, Diderot was often under police surveillance and at one point he was sentenced and incarcerated in the prison of Vincennes. Many of his supporters suffered even greater persecution and frightened contributors withdrew from their prior commitments. More than a decade before the first edition was completed, both Louis XV and Pope Clement XIII banned production and financing of the exhaustive Dictionary of Reason, as the Encyclopédie’s subtitle proclaims.

Rather than fleeing the country, however, Diderot continued the dangerous enterprise from his home in Paris. With financial support from Catherine the Great of Russia and secret backing from the king’s censor (Malesherbes) and the king’s mistress (Madame de Pompadour), Diderot labored on.  When printing in France became too risky, Diderot found publishers in Switzerland. While not known for his discretion, he managed to quietly produce new volumes, sending only the engraved plates out of the country for printing while authorities turned a pre-negotiated blind eye.

I’d only learned a part of this story from Professor Palmer back in 2011 when he led our class to an archival room in the campus library. Once seated in pairs behind long tables, we obediently donned the vinyl gloves that were to stay on throughout our visit. It wasn’t long before a tired-looking gentleman wheeled in two metal carts, loaded with an entire 28-volume set for us to examine.

Looking back, I realize that I had no idea what to expect. Printed in Italy sometime in the 1770s, the ancient books were enormous. Each cart appeared to weigh more than the unassuming curator charged with loading them up. Our soft-spoken host explained that only he could remove the volumes from the carts but that he was happy to deliver any volume to our seat where we could examine them one at a time. 

My partner and I chose one of the volumes of illustrations and opened to a random page. Seeing the astonishing level of detail contained on each plate blew my mind. As we leafed through, I found myself wanting to linger on certain pages—partly to absorb the content and partly to marvel over what lay in front of my eyes. Knowing our time was limited, however, we were careful to maintain a pace that allowed us to peek at a few different volumes, sampling several dozen plates before our hour was up.

One aspect that surprised me was the depth of knowledge already gathered about human anatomy. Detailed drawings of intricate portions of the circulatory system, skinless models of musculature not unlike what you’d find in a doctor’s office today, multiple views of the bones and tendons of the hand, cross-sections of the human head: these make up a tiny sampling. Even more engrossing were the sections on technology and craftsmanship: the inner workings of shipping locks; military use of trebuchets and catapults; drawings showing how to make knives, cookware, lace, furniture, paper, clocks, you name it. If it existed in late 18th-century Europe, you’ll likely find it in Diderot’s encyclopedia. There are 54 illustrations dedicated simply to the manufacture of glass.

The artistry employed to produce these frozen snapshots of human history is equally spellbinding—beauty encased in an idealized coating of precision. Yet, the illustrations account for less than half the work. The 17 volumes devoted to articles contain roughly 20 million words. It’s hard to imagine organizing that much information by hand. Now consider that each article, where appropriate, includes cross-references to pages in the related volume of illustrations.

Of particular interest was Diderot and d’Alembert’s Tree of Human Knowledge, which Professor Palmer had alluded to in class. This controversial 6-page foldout attempts to categorize all areas of human understanding by placing leaves of comprehension on a massive tree of knowledge. At first glance, the immense diagram seems like a useful way to visualize the encyclopedia’s massive and varied content. However, the Catholic Church viewed the chosen organization of subjects as an overt attempt to undermine its authority. Their assessment was not off base.

Unsuspecting readers now found Religion on a sub-branch of Meta-physics which was subordinate to Philosophy rather than dominating a category of its own in which man’s ability to reason plays no role. Subjects such as Black Magic, Divination, and Cosmology descend from the same hierarchy. The relative size of each leaf also says something about its importance—theology occupying no more space than mineralogy.

With tens of thousands of articles, the Encyclopédie is hardly a revolutionary treatise against religion or even monarchies. But Diderot, d’Alembert, and other contributors lightly salted the text with mild challenges to the political and spiritual authorities of the day. Like this gem, filed under Political Authority: “No man has received from nature the right to command other men.” Or, the multi-page logistical analysis of what it would have taken to actually build Noah’s Ark. The matter was treated with all seriousness but any halfway astute reader recognizes the absurdity of such a vessel.

It’s impossible to overstate the sacrifice that Diderot made by seeing the Encylopédie through to completion. He often took on articles that no one else seemed interested in writing, spending his days mastering subject matter— often through firsthand observation—and his nights cranking out essays by candlelight. He proofread and rewrote countless articles from less competent authors and was frequently harassed by personal threats and police raids. His finances suffered as did his eyesight.

Diderot’s seemingly unflinching commitment to enlightening the common man stifled his ability to advance his own philosophical arguments. While Diderot produced several other works throughout his lifetime, he never enjoyed the same level of notoriety nor the financial rewards that his friends and fellow contributors, Voltaire and Rousseau, achieved. Perhaps the most debilitating blow came after 20 years of toil, just as Diderot could finally see the project coming to a close. To his horror, Diderot learned that his publisher, Le Breton, had stricken passages that he deemed potentially offensive to Church and State from the final 10 volumes. Le Breton also burned the original manuscripts, rendering their reproduction impossible.

Deeply disillusioned and strapped for cash, Diderot nearly abandoned the project. Encouraged by friends and bankrolled by Catherine the Great, the crestfallen mastermind decided to move forward, now putting his energies into striking a deal with the king’s new censor to allow distribution of the Encyclopédie in France. Another 6 years would pass before the final volumes were sent to the original subscribers.

Sadly, Diderot never recovered from Le Breton’s betrayal. He died 12 years later, believing he’d failed to leave a significant imprint on posterity but satisfied that he’d at least lived an honorable life. He undoubtedly never thought that his work would one day be accessible in dozens of languages to anyone in the world with access to a global information network. But, I like to imagine that he fell asleep at night assured that certain students of French literature, living in the 21st century, might happen upon his back-breaking masterpiece and reverently stand in awe of his dedication to man’s enlightenment.

Other Resources

• Book Review, Enlightening the World by Philipp Blom
• Open Edition Books, Savoir et Matières
• University of Chicago RTFL Encyclopédie, Research & Archival Materials
• University of Michigan, The Encyclopedia of Diderot & Alembert, Collaborative Translation Project
• HistoryofInformation, Diderot & d’Alembert’s Encyclopédie, the Central Enterprise of the French Enlightenment
• Oregon State University, Banning Information in 18th Century France
• University of Melbourne, Mirror mirror on the wall, whose was the most influential encyclopaedia of them all
• Longreads Blog, How’s Diderot’s Encyclopedia Challenged the King
• ZSR Library, Encyclopédie, ou Dictionnaire Raisonné des Sciences, des Arts et des Métiers