Diderot's Encyclopédie (1751-1772): The Enlightenment in Print

The Encyclopédie, edited by Denis Diderot and Jean le Rond d’Alembert and published in Paris between 1751 and 1772, was the great collective work of the French Enlightenment. Its 17 volumes of text and 11 volumes of plates aimed to survey all human knowledge, from philosophy to pin-making, and to encourage readers to think for themselves. It survived official bans, a papal condemnation and the defection of its co-editor to become one of the most influential publications of the eighteenth century.

Background: from translation to new project

The Encyclopédie began as a commercial translation. In 1745 the Paris publisher André-François Le Breton obtained permission to publish a French version of Ephraim Chambers’s Cyclopaedia (1728), a successful English dictionary of arts and sciences. His first collaborators, the Englishman John Mills and the German Gottfried Sellius, fell out with him, and the project passed to the mathematician Jean-Paul de Gua de Malves.

Gua de Malves soon withdrew. In October 1747 Le Breton and his partners, the booksellers Briasson, David and Durand, gave the editorship to two younger men: Denis Diderot, a writer and translator from Langres, and Jean le Rond d’Alembert, already a respected mathematician and member of the Academy of Sciences.

Under their direction the plan grew from a translation into an entirely new and far larger work. The full title promised a Dictionnaire raisonné des sciences, des arts et des métiers, a “reasoned dictionary” of the sciences, the arts and the trades, written by “a society of men of letters”.

Prospectus and first volume

The project almost ended before it began. In July 1749 Diderot was arrested and held at the fortress of Vincennes for his Letter on the Blind, which was considered atheistic. He was released in November 1749 after promising good behaviour, partly because the publishers pleaded that their investment depended on him.

Diderot’s prospectus appeared in late 1750 and attracted subscribers. The first volume, covering the letter A, was published in June 1751. It opened with d’Alembert’s Preliminary Discourse, which became a manifesto of the Enlightenment.

The Discourse traced the origins of knowledge to the senses rather than to revelation, and presented a “tree of knowledge” adapted from the English philosopher Francis Bacon. Knowledge was divided according to three faculties of the mind: memory (history), reason (philosophy) and imagination (poetry and the arts). Theology was placed as one branch of philosophy, a quiet but significant demotion.

Denis Diderot was born in Langres, in eastern France, on 5 October 1713, the son of a master cutler. He had studied in Paris and lived precariously as a translator and writer, and his own philosophical views moved from deism towards materialism. Tireless and wide-ranging, he spent more than twenty years of his life on the Encyclopédie.

Jean le Rond d’Alembert, born in Paris in 1717, was the illegitimate son of the salon hostess Madame de Tencin and an artillery officer; he was named after the church where he had been abandoned as a baby. His reputation as a mathematician gave the project scientific credibility, and he oversaw the mathematical articles.

Contributors and contents

More than 140 contributors have been identified, though many articles are unsigned. They included Voltaire, who wrote articles such as “Esprit” and “Histoire”; Jean-Jacques Rousseau, who wrote on music and the article “Économie politique”; the physician François Quesnay on agriculture and economics; the administrator Anne-Robert-Jacques Turgot; and the baron d’Holbach on chemistry and mineralogy.

The most prolific was Louis, chevalier de Jaucourt, a wealthy scholar who wrote some 17,000 articles, roughly a quarter of the whole, often paying secretaries from his own pocket. Diderot himself wrote thousands of articles and edited and revised many more.

Unusually for its time, the Encyclopédie treated the “mechanical arts” with great respect. Diderot visited workshops, interviewed craftsmen and commissioned engravings showing how trades such as printing, glass-making, mining, weaving and pin manufacture actually worked. These plates remain one of the best visual records of pre-industrial technology.

Cross-references and hidden criticism

The editors used cross-references (renvois) to link related articles. In his own article “Encyclopédie”, Diderot explained that these could also serve to challenge received opinion, setting one article against another so that readers drew their own conclusions.

A frequently cited example is the article on cannibals (“Anthropophages”), which refers readers to the articles on the Eucharist and Communion. Such devices let contributors hint at criticism of religion and authority that a censor reading a single article might not notice.

Diderot stated the work’s aim in the same article: to change the common way of thinking. Most articles were in fact practical and uncontroversial, but the overall spirit favoured reason, religious toleration, scientific inquiry and useful knowledge over tradition and dogma.

Censorship battles

Opposition came from the Jesuits, the Jansenists, the Parlement of Paris and parts of the royal court. In 1752, after a scandal over a theology thesis by the abbé de Prades, a contributor, a royal decree of 7 February suppressed the first two volumes. Publication nevertheless continued, helped by the sympathetic director of the book trade, Chrétien-Guillaume de Lamoignon de Malesherbes, who reportedly warned Diderot of an impending police search and offered to hide his papers.

Volumes 3 to 7 appeared from 1753 to 1757. The climate then darkened. After Robert-François Damiens attacked Louis XV in January 1757, authorities became more hostile to dangerous writings. D’Alembert’s article “Genève” in volume 7 angered Geneva’s Protestant pastors and drew a reply from Rousseau that ended his friendship with the encyclopedists.

In 1758 the materialist book De l’esprit by Claude-Adrien Helvétius caused a further scandal, and d’Alembert withdrew from the editorship. In March 1759 the royal council revoked the Encyclopédie’s privilege, and on 3 September 1759 Pope Clement XIII placed it on the Index of Prohibited Books, ordering Catholics who owned copies to have them burned by a priest.

Diderot continued almost alone. The government, unwilling to ruin the publishers and the thousands of subscribers who had paid in advance, allowed the plates to appear under a separate permission and tolerated work on the text as long as it was discreet.

In 1764 Diderot discovered that Le Breton had secretly cut passages he thought dangerous from the proofs of the final volumes. Diderot was furious but carried on. The last ten volumes of text, 8 to 17, were issued together in 1765, bearing the false imprint of a Neuchâtel printer to give the authorities cover.

The eleven volumes of plates followed between 1762 and 1772, completing the work 25 years after Diderot and d’Alembert took charge. Supplements and an index produced by other publishers in the 1770s and 1780s were not edited by Diderot.

By the numbers

Spread and influence

The first edition was expensive and printed in about 4,000 copies, but cheaper reprints and editions in quarto and octavo formats from Geneva, Neuchâtel, Lausanne, Bern, Lucca and Livorno multiplied its reach. Historian Robert Darnton has estimated that roughly 24,000 to 25,000 copies of the various editions were sold before 1789, a large share of them in France.

The Encyclopédie influenced later reference works, including the Encyclopaedia Britannica, first published in Edinburgh from 1768. Its ideas, shared with works such as Voltaire’s Candide and Rousseau’s The Social Contract, helped create a public used to questioning authority.

Historians no longer describe the Encyclopédie as a direct cause of the French Revolution, and many of its contributors were moderate reformers rather than revolutionaries. It did, however, spread a confidence that reason, science and practical knowledge could improve human life, which became central to modern Western culture.

Myths and facts

Myth: the Encyclopédie was a radical, anti-religious pamphlet. Most of its articles were technical or descriptive, and some contributors were clergy. Its critical passages were scattered and often disguised.

Myth: Diderot wrote the Encyclopédie. He was its driving editor and a major author, but it was a collective work, and Jaucourt alone wrote more articles than Diderot.

Myth: it was the first encyclopedia. It built on earlier works, above all Chambers’s Cyclopaedia. What was new was its scale, its treatment of the trades and its critical spirit.

Timeline

• 1745: Le Breton plans a French translation of Chambers’s Cyclopaedia.
• 1747, October: Diderot and d’Alembert become editors.
• 1749, July–November: Diderot is imprisoned at Vincennes.
• 1751, June: Volume 1 is published with d’Alembert’s Preliminary Discourse.
• 1752, 7 February: A royal decree suppresses the first two volumes.
• 1758: D’Alembert withdraws as co-editor.
• 1759: The privilege is revoked and the Pope places the work on the Index.
• 1765: The final ten volumes of text are issued together.
• 1772: The last volume of plates is published.

Why it matters

The Encyclopédie showed that knowledge could be gathered, organised and shared by a community of writers independent of church and crown. By honouring science and craft alongside philosophy, and by teaching readers to compare and question, it became the clearest expression of the Enlightenment’s belief in progress through reason.