Diderot also contributed to literature, notably with his work Jacques le fataliste et son maître, which, in emulation of Sterne, challenged conventions regarding novels and their structure and content, while also examining philosophical ideas relating to free will. He is also known as the author of the essay Regrets on Parting with My Old Dressing Gown, upon which many an article and sermon about consumer desire have been based.

He was educated by the Jesuits, and became a bookseller in Paris. In 1743 he married Anne Toinette Champion, a devout Roman Catholic. He had affairs with the writer Madame Puisieux and with Sophie Volland, to whom he was constant for the rest of her life. His letters to her are among the most graphic of all the pictures that we have of the daily life of the philosophic circle in Paris.

Diderot's earliest works included a translation of Stanyan's History of Greece (1743); with two colleagues, François-Vincent Toussaint and Marc-Antoine Eidous, he produced a translation of James's Dictionary of Medicine (1746–1748) and about the same date he published a free rendering of Shaftesbury's Inquiry Concerning Virtue and Merit (1745), with some original notes of his own. He composed a volume of bawdy stories, the Les bijoux indiscrets (1748); in later years he repented of this work. In 1746 he wrote the Pensées philosophiques (1746), and he presently added to this a short complementary essay on the sufficiency of natural religion.

In 1747 he wrote the Promenade du sceptique, an allegory pointing first to the extravagances of Catholicism; second, to the vanity of the pleasures of that world which is the rival of the church; and third, to the desperate and unfathomable uncertainty of the philosophy which professes to be so high above both church and world.

Diderot's next piece was what first introduced him to the world as an original thinker, his famous Lettre sur les aveugles (1749). The immediate object of this short work was to show the dependence of men's ideas on their five senses. It considers the case of the intellect deprived of the aid of one of the senses; and in a second piece, published afterwards, Diderot considered the case of a similar deprivation in the deaf and mute.

The Lettre sur les sourds et muets, however, is substantially a digressive examination of some points in aesthetics. The philosophic significance of the two essays is in the advance they make towards the principle of Relativism. But what interested the militant philosophers of that day was an episodic application of the principle of relativism to the concept of God. What makes the Lettre sur les aveugles interesting is its presentation, in a distinct though undigested form, of the theory of variation and natural selection. It is worth noticing, too, as an illustration of the comprehensive freedom with which Diderot felt his way round any subject that he approached, that in this theoretic essay he suggests the possibility of teaching the blind to read through the sense of touch.

His speculation in the Lettre sur les aveugles was too hardy for the authorities, and he was thrown into the prison of Vincennes. Here he remained for three months; then he was released, to enter upon the gigantic undertaking of his life.

Encyclopédie
The bookseller and printer André Le Breton had applied to Diderot with a project for the publication of a translation into French of Ephraim Chambers's Cyclopaedia, or Universal Dictionary of Arts and Sciences, undertaken in the first instance by the Englishman John Mills, and the German, Gottfried Sellius. Diderot accepted the proposal, but in his busy and pregnant intelligence the scheme became transformed. Instead of a mere reproduction of the Cyclopaedia, he persuaded Le Breton to enter upon a new work, which should collect under one roof all the active writers, all the new ideas, all the new knowledge, that were then moving the cultivated class of the Republic of Letters to its depths, but still were comparatively ineffectual by reason of their dispersion.

His enthusiasm infected the publishers; they collected a sufficient capital for a vaster enterprise than they had at first planned; Jean le Rond d'Alembert was persuaded to become Diderot's colleague; the requisite permission was procured from the government; in 1750 an elaborate prospectus announced the project to a delighted public; and in 1751 the first volume was given to the world. The last of the letterpress was issued in 1765, but it was 1772 before the subscribers received the final volumes of the Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers.

These twenty years were to Diderot years not merely of incessant drudgery, but of harassing persecution, and of injury from the desertion of friends. The ecclesiastical party detested the Encyclopédie, in which they saw a rising stronghold for their philosophic enemies. By 1757 they could endure the sight no longer. The subscribers had grown from 2,000 to 4,000, and this was a right measure of the growth of the work in popular influence and power. The Encyclopédie was threatening to the governing social classes of France (aristocracy) because it takes for granted the justice of religious tolerance, freedom of thought and the value of science and industry. It asserts the democratic doctrine that it is the common people in a nation whose lot ought to be the main concern of the nation's government.

There was a contemporary belief that the Encyclopédie was the work of an organized band of conspirators against society, and that the dangerous ideas they held were now made truly formidable by their open publication. In 1759 the Encyclopédie was formally suppressed. The decree, however, did not arrest the continuance of the work, which went on, but with its difficulties increased by the necessity of being clandestine.

D'Alembert withdrew from the enterprise and other powerful colleagues, Anne Robert Jacques Turgot, Baron de Laune, among them, declined to contribute further to a book which had acquired an evil fame. Diderot was left to bring the task to an end as he best could. He wrote several hundred articles, some of them very slight, but many of them most laborious, comprehensive and ample. He wore out his eyesight in correcting proofs, and in bringing the manuscript of less competent contributors into decent shape. He spent his days in the workshops, mastering the processes of manufacturing, and his nights in reproducing on paper what he had learnt during the day. And he was incessantly harassed all the time by alarms of a descent from the police.

At the last moment, when his immense work was just drawing to an end, he encountered one last and crowning mortification: he discovered that the bookseller, fearing the displeasure of the government, had struck out from the proof sheets, after they had left Diderot's hands, all passages that he chose to think too dangerous. The monument to which Diderot had given the labour of twenty long and oppressive years was irreparably mutilated and defaced.

Other works
Although the Encyclopédie was Diderot's monumental work, he was the author of many pieces that sowed nearly every field of intellectual interest with new and fruitful ideas. He wrote sentimental plays, Le Fils naturel (1757) and Le Père de famille (1758), accompanying them with essays on dramatic poetry, including especially the Paradoxe sur le comédien, in which he announced the principles of a new drama, the serious, domestic, bourgeois drama of real life, in opposition to the stilted conventions of the classic French stage.

His art criticism was also highly influential. His Essai sur la peinture was described by Johann Wolfgang von Goethe, who thought it worth translating, as "a magnificent work, which speaks even more helpfully to the poet than to the painter, though to the painter too it is as a blazing torch."

Diderot's most intimate friend was the philologist Friedrich Melchior Grimm. Grimm wrote newsletters to various high personages in Germany, reporting what was going on in the world of art and literature in Paris, then the intellectual capital of Europe. Diderot helped Grimm between 1759 and 1779, by writing for him an account of the annual exhibitions of paintings in the Paris Salon. These reports are highly readable pieces of art criticism. According to Charles Augustin Sainte-Beuve, they initiated the French into a new sentiment, and introduced people to the mystery and purport of colour by ideas. "Before Diderot," Anne Louise Germaine de Staël wrote, "I had never seen anything in pictures except dull and lifeless colours; it was his imagination that gave them relief and life, and it is almost a new sense for which I am indebted to his genius."

Jean-Baptiste Greuze was Diderot's favourite among contemporary artists. Greuze's most characteristic pictures were the rendering in colour of the same sentiment of domestic virtue and the pathos of common life, which Diderot had attempted to represent upon the stage. For Diderot was above all things interested in the life of men, not the abstract life of the race, but the incidents of individual character, the fortunes of a particular family, the relations of real and concrete motives in this or that special case. He delighted with the enthusiasm of a born casuist in curious puzzles of right and wrong, and in devising a conflict between the generalities of ethics and the conditions of an ingeniously contrived practical dilemma. Diderot's interest expressed itself in didactic and sympathetic form.

In two, however, of the most remarkable of all his pieces, this interest is not sympathetic, but ironical. Jacques le fataliste (written in. 1773, but not published until 1796) is in manner an imitation of Tristram Shandy and The Sentimental Journey. His dialogue Le Neveu de Rameau (Rameau's Nephew) is a "farce-tragedy" reminiscent of the Satires of Horace. A favorite classical author of Diderot's, Horace's words "Vertumnis quotquot sunt natis iniquis" are quoted at the top of the "Nephew". Diderot's intention in writing the dialogue has been matter of dispute; whether it was designed to be merely a satire on contemporary manners, or a reduction of the theory of self-interest to an absurdity, or the application of irony to the ethics of ordinary convention, or a mere setting for a discussion about music, or a vigorous dramatic sketch of a parasite and a human original.

Whatever its intent, is a remarkable conversation, emblematic of an era of that held the arts of conversation in the highest esteem. The writing and publication history of the "Nephew" is likewise a bit mysterious. Diderot never saw the work through to publication during his lifetime, but there is every indication it was of continual interest to him. Though the original draft was written in 1761, he made additions to it year after year until his death twenty-three years later. Goethe's translation (1805) was the first introduction of Le Neveu de Rameau to the European public. After executing it, he gave back the original French manuscript to Friedrich Schiller, from whom he had it. No authentic French copy of it appeared until the writer had been dead forty years (1823).

Diderot's miscellaneous pieces range from a graceful trifle like the Règrets sur ma vieille robe de chambre up to Le rêve de D'Alembert, where he plunges into the depths of the controversy as to the ultimate constitution of matter and the meaning of life. Diderot was not a coherent and systematic thinker, but rather "a philosopher in whom all the contradictions of the time struggle with one another" (Rosenkranz). He did not develop a system of materialism, but he contributed many of the most declamatory pages of the Système de la nature of his friend Paul Henri Thiry, baron d'Holbach, styled by some "the very Bible of atheism".

Varied and incessant as was Diderot's mental activity, it was not of a kind to bring him riches. He secured none of the posts that were occasionally given to needy men of letters; he could not even obtain that bare official recognition of merit which was implied by being chosen a member of the Académie française. When the time came for him to provide a dowry for his daughter, he saw no other alternative than to sell his library. When the Catherine II of Russia heard of his straits, she commissioned an agent in Paris to buy the library, and then requested the philosopher to retain the books in Paris until she required them, and to constitute himself her librarian, with a yearly salary. In 1773 and 1774 Diderot spent some months at the empress's court at St Petersburg.

He died of emphysema and dropsy in Paris on July 31, 1784, and was buried in the city's Eglise Saint-Roch. His heirs sold his vast library to Catherine II, who had it deposited at the Russian National Library.