(1713-1784)
French man of letters and philosopher who, from 1745 to 1772, served as chief editor of the Encyclop+¬die, one of the principal works of the Age of Enlightenment.

Diderot was the son of a widely respected master cutler. He was tonsured in 1726, though he did not in fact enter the church, and was first educated by the Jesuits at Langres. From 1729 to 1732 he studied in Paris at the Coll+¿ge d'Harcourt or at the Lyc+¬e Louis-le-Grand or possibly at both these institutions, and he was awarded the degree of master of arts in the University of Paris on Sept. 2, 1732. He then studied law as an articled clerk in the office of Cl+¬ment de Ris but was more interested in languages, literature, philosophy, and higher mathematics. Of his life in the period 1734 to 1744 comparatively little is known. He dropped an early ambition to enter the theatre and, instead, taught for a living, led a penurious existence as a publisher's hack, and wrote sermons for missionaries at 50 +¬cus each. At one time he seems to have entertained the idea of taking up an ecclesiastical career, but it is most unlikely that he entered a seminary. Yet his work testifies to his having gone through a religious crisis, and he progressed relatively slowly from Roman Catholicism to deism and then to atheism and philosophical materialism. That he led a disordered and bohemian existence at this time is made clear in his posthumously published novel, Le Neveu de Rameau (Rameau's Nephew). He frequented the coffeehouses, particularly the R+¬gence and the Procope, where he met the philosopher Jean-Jacques Rousseau in 1741 and established a friendship with him that was to last for 15 years, until it was broken by a quarrel.

In 1741 he also met Antoinette Champion, daughter of a linendraper, and in 1743 he married her–secretly, because of his father's disapproval. The relationship was based on romantic love, but the marriage was not a happy one owing to incompatible interests. The bond held, however, partly through a common affection for their daughter, Ang+¬lique, sole survivor of three children, who was born in 1753 and whom Diderot eventually married to Albert de Vandeul, a man of some standing at Langres. Diderot lavished care over her education, and she eventually wrote a short account of his life and classified his manuscripts.

In order to earn a living, Diderot undertook translation work and in 1745 published a free translation of the Inquiry Concerning Virtue by the 3rd Earl of Shaftesbury, whose fame and influence he spread in France. Diderot's own Pens+¬es philosophiques (1746; Philosophic Thoughts), an original work with new and explosive anti-Christian ideas couched in a vivid prose, contains many passages directly translated from or inspired by Shaftesbury. The proceeds of this publication, as of his allegedly indecent novel Les Bijoux indiscrets (1748), were used to meet the demands of his mistress, Madeleine de Puisieux, with whom he broke a few years later. In 1755 he met Sophie Volland, with whom he formed an attachment that was to last more than 20 years. The liaison was founded on common interests, natural sympathy, and a deepening friendship. His correspondence with Sophie, together with his other letters, forms one of the most fascinating documents on Diderot's personality, enthusiasms, and ideas and on the intellectual society of Louise d'+ëpinay, F.M. Grimm, the Baron d'Holbach, Ferdinando Galiani, and other deistic writers and thinkers (Philosophes) with whom he felt most at home. Through Rousseau, Diderot met +ëtienne Bonnot de Condillac, the philosopher, and for a time the three friends dined together at the Panier Fleuri.

In 1745 the publisher Andr+¬ Le Breton approached Diderot with a view to bringing out a French translation of Ephraim Chambers' Cyclopaedia, after two other translators had withdrawn from the project. Diderot undertook the task with the distinguished mathematician Jean Le Rond d' Alembert as coeditor but soon profoundly changed the nature of the publication, broadening its scope and turning it into an important organ of radical and revolutionary opinion. He gathered around him a team of dedicated litterateurs, scientists, and even priests, many of whom, as yet unknown, were to make their mark in later life. All were fired with a common purpose: to further knowledge and, by so doing, strike a resounding blow against reactionary forces in church and state. As a dictionnaire raisonn+¬ (rational dictionary“), the Encyclop+¬die was to bring out the essential principles and applications of every art and science. The underlying philosophy was rationalism and a qualified faith in the progress of the human mind.

In 1749 Diderot published the Lettre sur les aveugles (An Essay on Blindness), remarkable for its proposal to teach the blind to read through the sense of touch, along lines that Louis Braille was to follow in the 19th century, and for the presentation of the first step in his evolutionary theory of survival by superior adaptation. This daring exposition of the doctrine of materialist atheism, with its emphasis on human dependence on sense impression, led to Diderot's arrest and incarceration in the prison of Vincennes for three months. Diderot's work on the Encyclop+¬die, however, was not interrupted for long, and in 1750 he outlined his program for it in a Prospectus, which d'Alembert expanded into the momentous Discours pr+¬liminaire (1751). The history of the Encyclop+¬die, from the publication of the first volume in 1751 to the distribution of the final volumes of plates in 1772, was checkered, but ultimate success was never in doubt. Diderot was undaunted by the government's censorship of the work and by the criticism of conservatives and reactionaries. A critical moment occurred in 1758, on the publication of the seventh volume, when d'Alembert resigned on receiving warning of trouble and after reading Rousseau's attack on his article Gen+¿ve.” Another serious blow came when the philosopher Helv+¬tius' book De l'esprit (“On the Mind”), said to be a summary of the Encyclop+¬die, was condemned to be burned by the Parlement of Paris, and the Encyclop+¬die itself was formally suppressed. Untempted by Voltaire's offer to have the publication continued outside France, Diderot held on in Paris with great tenacity and published the Encyclop+¬die's later volumes surreptitiously. He was deeply wounded, however, by the discovery in 1764 that Le Breton had secretly removed compromising material from the corrected proof sheets of about 10 folio volumes. The censored passages, though of considerable interest, would not have made an appreciable difference on the impact of the work. To the 17 volumes of text and 11 volumes of plates (1751-72), Diderot contributed innumerable articles partly original, partly derived from varied sources, especially on the history of philosophy (“Eclectisme” [“Eclecticism”]), social theory (“Droit naturel” [“Natural Law”]), aesthetics (“Beau” [“The Beautiful”]), and the crafts and industries of France. He was moreover an energetic general director and supervised the illustrations for 3,000 to 4,000 plates of exceptional quality, which are still prized by historians today. Philosophical and scientific works. While editing the Encyclop+¬die, Diderot managed to compose most of his own important works as well. In 1751 he published his Lettre sur les sourds et muets (“Letter on the Deaf and Dumb”), which studies the function of language and deals with points of aesthetics, and in 1754 he published the Pens+¬es sur l'interpr+¬tation de la nature (“Thoughts on the Interpretation of Nature”), an influential short treatise on the new experimental methods in science. Diderot published few other works in his lifetime, however. His writings, in manuscript form, were known only to his friends and the privileged correspondents of the Correspondance litt+¬raire, a sort of private newspaper edited by Baron Grimm that was circulated in manuscript form. The posthumous publication of these manuscripts, among which are several bold and original works in the sciences, philosophy, and literature, have made Diderot more highly appreciated in the 20th century than he was in France during his lifetime.

Among his philosophical works, special mention may be made of L'Entretien entre d'Alembert et Diderot (written 1769, published 1830; Conversation Between d'Alembert and Diderot“), Le R+¬ve de d'Alembert (written 1769, published 1830 “D'Alembert's Dream”), and the El+¬ments de physiologie (1774-80). In these works Diderot developed his materialist philosophy and arrived at startling intuitive insights into biology and chemistry in speculating on the origins of life without divine intervention, for instance, he foreshadowed the evolutionary theories of Charles Darwin and put forth a strikingly prophetic picture of the cellular structure of matter. Though Diderot's speculations in the field of science are of great interest, it is the dialectical brilliance of their presentation that is exceptional. His ideas, often propounded in the form of paradox, and invariably in dialogue, stem from a sense of life's ambiguities and a profound understanding of the complexities and contradictions inherent in human nature.”

Four works of prose fiction by Diderot were published posthumously: the novel La Religieuse (written 1760, published 1796; The Nun); the novel Jacques le fataliste et son ma+«tre (written 1773, published 1796; Jacques the Fatalist); Le Neveu de Rameau (written between 1761 and 1774, published in German 1805; Rameau's Nephew), a character sketch in dialogue form; and Suppl+¬ment au voyage de Bougainville (written 1772, published 1796; Supplement to Bougainville's Voyage“).

La Religieuse describes the distressing and ultimately tragic experiences of a girl who is forced to become a nun against her will. In Jacques le fataliste, Jacques, who believes in fate, is involved in an endless argument with his master, who does not, as they journey along retelling the story of their lives and loves. Diderot's philosophical standpoint in this work is ambivalent, as is his ethical standpoint in Le Neveu de Rameau. The latter work is a dialogue between Diderot and a bohemian musician who is based partly on the nephew of the French composer Jean-Philippe Rameau. This work may properly be called a satire, since it challenges the cant of contemporary society and the hypocrisy of its morality. Rameau's nephew is depicted as a shamelessly selfish parasite, an eccentric, and a musician who is gifted yet unable to make his mark through insufficient talent. His dialogue with Diderot is spontaneous and witty, and there are digressions, a lengthy disquisition on contemporary musical controversies, and diatribes against Diderot's own enemies. This brilliantly conceived, highly original and entertaining divertissement reveals the complexity of Diderot's personality and of his philosophical ideas. In the Suppl+¬ment au voyage de Bougainville Diderot, in discussing the mores of the South Pacific islanders, emphasizes his conception of a free society based on tolerance and develops his views on sexual freedom.

Diderot's major plays, Le Fils naturel (1757; The Illegitimate Son”) and Le P+¿re de famille (1758 “The Father of the Family”), make tedious reading today. His theories on drama, however, expounded in Entretiens sur le fils naturel (1757 “Discussion on the Illegitimate Son”) and Discours sur la po+¬sie dramatique (“Discourse on Dramatic Poetry”), were to exercise a determining influence on the German dramatist Gotthold Lessing. Taking as his starting point the com+¬die larmoyante, Diderot stressed the need for greater realism on the stage and favoured the serious bourgeois drama of real life. Characters should be presented against their milieu and belong to specific professions, so that the moral and social implications of the play, which he considered to be of primary importance, should have greater impact. In his Paradoxe sur le com+¬dien (written 1773, published 1830), Diderot argued that great actors must possess judgment and penetration without “sensibility”–i.e., without actually experiencing the emotions they are portraying as characters on the stage. Although Diderot wrote literary criticism, it is as the first great art critic, covering the Paris Salons, or annual art exhibitions, for the Correspondance litt+¬raire, that he is best remembered. His analysis of art, artists, and the technique of painting, together with the excellence of his taste and his style, have won him posthumous fame his Essai sur la peinture (written 1765, published 1796 “Essay on Painting”), especially, was admired by Goethe and later by the 19th-century poet and critic Charles Baudelaire.“

The completion of the Encyclop+¬die in 1772 left Diderot without a source of income. To relieve him of financial worry, Catherine the Great of Russia first bought his library through an agent in Paris, requesting him to retain the books until she required them, and then appointed him librarian on an annual salary for the duration of his life. Diderot went to St. Petersburg in 1773 to thank her for her financial support and was received with great honour and warmth. He wrote for her the Plan d'une universit+¬ pour le gouvernement de Russie (Plan of a University for the Government of Russia”). He stayed five months, long enough to become disillusioned with enlightened despotism as a solution to social ills.

In 1774 Diderot, now old and ill, worked on a refutation of Helv+¬tius' work De l'homme (1772; On Man“), which was an amplification of the destroyed De l'esprit. He wrote Entretien d'un philosophe avec la Mar+¬chale (“Conversation with the Mar+¬chale”) and published in 1778 Essai sur les r+¿gnes de Claude et de N+¬ron (“Essay on the Reigns of Claudius and Nero”). Usually known as Essai sur la vie de S+¬n+¿que (“Essay on the Life of Seneca”), the work may be regarded as an apologia for that Roman satirist and philosopher. Diderot's intimate circle was dwindling. Mme d'+ëpinay and d'Alembert died, leaving only Grimm and Baron d'Holbach. Slowly Diderot retired into the shell of his own personal and family life. The death of Sophie Volland in February 1784 was a great grief to him he survived her by a few months, dying of coronary thrombosis in the house in the rue de Richelieu that Catherine the Great had put at his disposal. Apocryphally, his last words were: “Le premier pas vers la philosophie, c'est l'incr+¬” (“The first step toward philosophy is incredulity”). Through the intervention of his son-in-law, he was buried in consecrated ground at Saint-Roch. ”