DIDEROT, DEN-is (1713-1784), one of the most active and original of the famous group of men of letters in France in the middle of the 18th century. He was born at Langres in 1713 ; he was educated by the Jesuits, like most of those who afterwards became the bitterest enemies of Catholicism ; aud, when his education was at an etti, he vexed his brave and worthy father's heart by turning away from respectable callings, like law or medicine, and throw-ing himself into the vagabond life of a bookseller's hack in Paris. An imprudent marriage (1743) did not better his position, His wife was a devout Catholic, but her piety did not restraiu a narrow and fretful temper, and Diderot's domestic life was irregular and unhappy. He sought con-solation for chagrins at home in attachments abroad, first with a Madame Puisieux, a fifth-rate female scribbler, and then with Mdlle. Voland, to whom he wa.s 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 ire Paris. An interesting contrast may be made between the Bohentianism of the famous literary set who supped at the Turk's Head with the Tory Johnson and the Conservative Burke for their oracles, and the Bohemianism o' the set who about the same time diued once a week at the Baron D'Hulbach's, to listen to the wild sallies and the inspiring declamations of Diderot. For Diderot was not a great writer ; he stands out as a fertile, suggestive, and daring thinker, and a prodigious and most eloquent talker.

Diderot's earliest writings were of as little importance as Goldsmith's Enquiry into the State of Polite .Learning or Burke's Abridgement of _English History. He earned 100 croWIIS by translating Stanyan's History of Greece ; with two colleagues he produced a translatio, of James's Dictionary r,..! Medicine; and about the same date (1745) he published a free rendering of Shaftesbury's Inquiry Concerning Virtue and Merit, with some original notes of his own. With strange and characteristic versatility-, he turned from ethical specu-lation to the composition of a volume of stories, which are gross without liveliness, and impure without wit. In later years he repented of this shameless work, just as Boccaccio is said in the day of his gray hairs to have thought of the sprightliness of the Decanteron with strong remorse. From tales Diderot went back to the more congenial region of philosophy-. Between the morning of Good Friday and the eveiting of Easter Monday he wrote the Philosophic Thoughts (1746), and he presently added to this a short complementary essay an the Sufficiency of Katural The gist of these performances is to press the ordinary rationalistic objections to a supernatural revelation ; but though Diderot did not at this time pass out ieto the wilderness beyond natural religion, yet there are signs that he accepted that less as a positive doctrine, resting on grounds of its own, than as a convenient point of attack against Christianity. In 1747 he wrote the Sceptic's TYa/k, a rather poor 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 Letter on the Blind (1749). The immediate object of this ahort but pithy writing 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 dumb. The Letter on .Deaf-Mutes, however, is substantially a digressive examination of some points in xsthetics. The philoaophic significance of the two essays is in the advance they make towards the principle of Relativity. But what interested the militant philosophers of that day was an episodic application of the principle of relativity to the master-conception of God. What makes the Letter 021 the Blind interesting at the present moment is its presentation, in a distinct though undigested form, of the modern. theory of variability, and of survival by superior adaptation. It is worth noticing, too, as an illustration of the comprehen-sive 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. If the Letter 021 the Blind introduced Diderot into the worshipful company of the philosophers, it also introduced him to the penalties of philosophy. His speculation was too hardy for the authorities, and he was thrown into the prison of Vincennes. Here he remained for three months ; then lie was released, to enter upon the gigantic undertaking of his life.

A certain bookseller had applied to him with a project for the translation into French of Ephraim Chambers's lopcedla. Diderot accepted the proposal, but in his busy and pregnant intelligence the scheme became trans-formed. Instead of a. mere reproduction of Chambers, he persuaded the bookseller 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 to its depths, but still were compara-tively 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 ; 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 letter-press was issued in 1765, but it was 1772 before the subscribers received the final volumes of the plates. These twenty years were to Diderot years not merely of incessant drudgery, but of harassing persecution, of sufferings from the cabals of enemies,and of injuryfrom the desertion of friends. The ecclesiastical party detested the Encyclopceclia, in which they saw a rising stronghold for their philosophic enemies. I3y 1757 they could endure the sight DO longer. The sub-scribers had grown from 2000 to 4000, and this was a right measure of the growth of the work in popular influence and power. To any one who turns over the pages of these redoubtable volumes now, it seems surprising that their doctrines should have stirred such portentous alarm. There is no atheism, no overt attack on any of the cardinal mysteries of the faith, no direct denunciation even of the notorious abuses of the church. Yet we feel that the atmosphere of the book may well have been displeasing to authorities who had not yet learnt to encounter the modern spirit on equal terms. The Encyclopcedia takes for granted the justice of religious tolerance and speculative freedom. It asserts in distinct tones 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. From beginning to end it is one unbroken process of exaltation of scientific knowledge on the one hand, and pacific industry on the other. All these things were odious to the old governing classes of France ; theirspirit was absol utist, ecclesiastical, and military. Perhaps the most alarming thought of all was the current belief that the Eneyelopcedia was the work of an organized band of conspirators against society, and that a, pestilent doctrine was now made truly formidable by the confedera-tion of its preachers into an open league. 'When the seventh volume appeared, it contained an article on " Geneva," written by D'Alembert. The writer contrived a panegyric on the pastors of Geneva, of which every word was a stinging reproach to the abb6s and prelates of Versailles. At the same moment Helvkins's book, L'Esprit, appeared, and gave a still more profound, and, let us add, a more reasonable shock to the ecclesiastical party. Authority could brook no more, and in 1759 the Eneyelopcedia was formally suppressed.

The decree, however, did not arrest the continuance of the work. The connivance of the authorities at the breach of their own official orders was common in those times of distracted government. The work went on, but with its difficulties increased by the necessity of being clandestine. And a worse thing than troublesome interference by the police now befell Diderot. D'Alembert, wearied of shifts and indigpities, withdrew from the enterprise. Other powerful colleagues, Turgot among them, declined to con-tribute further to a book which had acquired an evil fame. Diderot was left to bring the task to an end as he best could. For seven years he laboured like a slave at the oar. 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 he wearied his soul in bringing the manuscript of less coin petent contributors into decent shape. He spent his day: in the workshops, mastering the processes of manufactures, and his nights in reproducing on paper what ha 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 ont from the proof sheets, after they had left Diderot's hands, all passages that he chose to think too hardy. The monument to which Diderot had given the labour of twenty long and oppressive years was irreparably mutilated and defaced. It is calculated that the average annual salary received by Diderot for his share in the Eneyeloprdia was about X120 sterling. " A nd then to think," said Voltaire, " that. an army contractor makes S800 in a day I" Although the Eacyclopcedia was Diderot's monumental work, he is the author of a shower of dispersed pieces that sowed nearly every field of intellectual interest with new and fruitful ideas. We find. no masterpiece, but only thoughts for masterpieces ; no creation, but a criticism with the quality to inspire and direct creation. He wrote plays - le Fils Taturel and le Pere de I'amille - and they are, very insipid performances in the sentimental vein. Ent he accompanied them by essays on dramatic poetry, including especially the Paradoxe sur le Comed-ien, 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. It was Diderot's lessons and example that gave a. decisive bias to the dramatic taste of Lessing, whose plays, and his //amburgische Dramaturgic (1768), mark so important an epoch in the history of the modern theatre. In the pictorial art, Diderot's criticisms are no less rich, fertile, and wide in their ideas. His article on " Beauty " in the Encydopcedia shows that he had mastered and passed beyond the metaphysical theories on the subject, and the Essay on Painting was justly described by 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 Grimm, one of the conspicuous figures of the philosophic body. G rinnn wrote news-letters to various high personages in Germany, reporting what was going on in the world of art and literature in Paris, then without a rival as the capital of the intellectual activity of Europe. Diderot helped his friend at one time and another between 1759 and 1779, by writing for him an account of the annual exhibitions of paintings. These &dons are among the most readable of all pieces of art criticism. They have a freshness, a reality, a life, which took their readers into a different world from the dry- and conceited pedantries of the ordinary virtuoso. As has been said by Ste-Beuve, they initiated the French into a new sentiment, and. introduced people to the mystery- and purport of colour by ideas. " Before Diderot," Madame Necker said, " I had never seen anything in pictures except dull and lifeless colonts ; it was his imagi-nation that gave them relief and life, and it is almost a new sense for which I am indebted to his genius."

Greuze was Diderot's favourite among contemporary artists, and it is easy to see why. Grenze's most character-istic pictures were the rendering in colour of the same senti-ment of domestic virtue and the pathos of common life, which Diderot attempted with inferior success 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, particu-lar 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 diletnma. Mostly his interest expressed itself in didactic and sy-mpa-thetic form ; in two, however, of the most remarkable of all his pieces, it 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. Few modern readers will find in it any true diversion. In spite of some excellent criticisms dispersed here and there, and in spite of one or two stories th:it are not without a certain effective realism, it must as a whole be pronounced savourless, forced, and as leaving un-moved those springs of laughter and of tears which are the common fountain of humour. Ranteatt's Yephew is a far superior performance. If there were any inevitable compul-sion to name a masterpiece for Diderot, one must select this singular " farce-tragedy." Its intention 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 an ironi-cal clencher 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. There is no dispute as to its curious literary flavour, its mixed qualitieS of pungency, bitterness, pity, and, in places, unflinching shamelessness. Goethe's translation (1805) was the first introduction of Rameau's Nephew to the European public. After executing it, be gave back the original French manu-script' to Schiller, from whom he had it. No authentic French copy of it appeared until the writer had been nearly forty years in his grave (1823).

It would take several pages of this encyclopdia merely to contain the list of Diderot's miscellaneous pieces, from an infinitely graceful trifle like the Regrets on Hy Old Dressing GOMM up to D'Alembert's Dream, where he plunges into the depths of the controversy as to the ultimate con-stitution of matter and the meaning of life. It is a migtake to set down Diderot for a coherent and systematic materialist. We ought to look upon him "as a philosopher in whom all the contradictions of the time struggle with one another " (Rosenkranz). That is to say, he is critical and not dogmatic. There is no unity in Diderot, as there was in Voltaire or in Rousseau. Just as in cases of conduct he loves to make new ethical assumptions and argue them out as a professional sophist might have done, so in the speculative problems as to the organization of matter, the origin of life, the compatibility between physiological machinery and free will, he takes a certain stand-point, and follov.-s it out more or less digressively to its consequences. He seizes an hypothesis and works it to its end, and this made him the inspirer in others of materialist doctrines which they held more definitely than he did. Just as Diderot could not attain to the concentration, the positive-ness, the finality of aim needed for a master-piece of literature, so he could not attain to those qualities in the way of dogma and system. Yet he drew at last to the conclusions of materialism, and contributed many of its most declamatory pages to the S'ysteme de la Tature of his friend D'Holbach, - the very Bible of atheism, as some one styled it. All that he saw, if we reduce his opinions to formulas, was motion in space : " attraction and repulsion, the only truth." If matter produces life by spontaneous generation, and if man has no alternative but to obey the compulsion of nature, what remains for God to do ?

In proportion as these conclusions deepened in him, the more did Diderot turn for the hope of the race to virtue ; in other words, to such a regulation of conduct and motive as shall make us tender, pitiful, simple, contented. Hence his one great literary passion, his enthusiasm for Richardson, our English novelist. Hence, also, his deepening aversion for the political sy-stem of France, which made the realiza-tion of a natural and contented domestic life so hard. Diderot had almost as much to say against society as even Rousseau himself. The difference between them was that Rousseau was a fervent theist. The atheism of the Holbachians, as he called Diderot's group, was intolerable to him.; and this feeling, aided by certain private per-versities of humour, lecl to a breach of what had once been an intimate friendship between Rousseau and Diderot (1757). Diderot was still alive when the Confessions appeared, and he was so exasperated by Rousseau's stories about Grimm, then and always Diderot's intimate, that in 1782 he transformed a life of Seneca, that he had written four years earlier, into an Essay on the Reigns of Clamlins and Xero, which is much less an account of Seneca than a vindication of Diderot and Grimm, and is one of the most rambling and inept productions in literature. As for the merits of the old quarrel between ROUSSCall and Diderot, WC may agree with the latter, that too many sensible people would be in the wrong if jean Jacques was in the right.

Varied and incessant as was Diderot's mental activity, it wa,s 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 recogni-tion of merit which was implied by being chosen a member of the Academy. The time came for him to provide a dower for his daughter, and he saw no other alternative than to sell his library. When the empress Catherine of Russia heard of his straits, she conunissioned an agent in Paris to buy the library at a price equal to about £1000 of our money, and then she handsomely 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 Diderot started on an expedition to thank his imperial benefactress in person, and he passed some months at St Petersburg. The empress received him cordially. The strange pair passed their afternoons in disputes on a thousand points of high philosophy, and they debated with a vivacity and freedom not usual in courts.

" Fi, done," said Catherine one day, when Diderot hinted that he argued with her at a disadvantage, "is there any , difference among men?" Diderot returned home in 1774. , Ten years remained to him, and he spent them in the in-. dustrious acquisition of new knowledge, in the composition cf a host of fragmentary pieces, some of them mentioned above, and in luminous declamations with his friends. All accounts agree that Diderot was seen at his best in con-versation. " He who only knows Diderot in his writings," says Marmontel, " does not know him at all. When he grew animated in talk, and allowed his thoughts to flow in all their abundance, then he became truly ravishing. In his writings he had not the art of ensemble ; the first operation which orders and places everything was too slow and too painful to him." Diderot himself was conscious of the want of literary merit in his pieces. In truth he set no high value on what he had. done. It is doubtful whether he was ever alive to the waste that circumstance and temperament together made of an intelligence from which, if it had been free to work sy-stematically, the world of thought had so much to hope. He was one of those simple, disinterested, and intellectually sterling workers to whom their own personality is as nothing iu presence of the vast subjects that engage the thoughts of their lives. He wrote what he found to write, and left the piece, as Carlyle has said, " on the waste, of accident, with an ostrich-like indifference." When he heard one day that a collected edition of his works was in the press at Amsterdam, he greeted the news with " peals of laughter," so well did he know, the.haste and the little heed with which those works had been dashed off.

Diderot died in the month of July 1784, six years after Voltaire and Rousseau, one year after his old colleague D'Alembert, and five years before D'Holbach, his host and intimate for a lifetime. Notwithstanding Diderot's peals of laughter at the thought, there is now just completed - nearly a hundred years since his death - an elaborate and exhaustive collection of his writings in twenty stout volumes, edited by MM. Assezat and Tourneux. mo.)