It would take several pages merely to contain the list of Diderot’s miscellaneous pieces, from an infinitely graceful trifle like the Regrets 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. It is a mistake 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 standpoint, and follows it out more or less digressively to its consequences. He seizes a 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 positiveness, the finality of aim needed for a masterpiece 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 Système de la nature 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 formulae, 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, the English novelist. Hence, also, his deepening aversion for the political system of France, which makes the realization 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 perversities of humour, led to a breach of what had once been an intimate friendship between Rousseau and Diderot (1757). Diderot was still alive when Rousseau’s 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 Essai sur les règnes de Claude et de Néron (1778-1782), 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 Rousseau and Diderot, we 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 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 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 commissioned an agent in Paris to buy the library at a price equal to about £1000 of English money, and then 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, donc,” 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 industrious acquisition of new knowledge, in the composition of 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 conversation. “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 systematically, 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 in 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 on the 30th 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, an elaborate and exhaustive collection of his writings in twenty stout volumes, edited by MM. Assézat and Tourneux, was completed in 1875-1877.
Authorities.—Studies on Diderot by Scherer (1880); by E. Faguet (1890); by Sainte-Beuve in the Causeries du lundi; by F. Brunetière in the Études critiques, 2nd series, may be consulted. In English, Diderot has been the subject of a biography by John Morley [Viscount Morley of Blackburn] (1878). See also Karl Rosenkranz, Diderots Leben und Werke (1866). For a discussion of the authenticity of the posthumous works of Diderot see R. Dominic in the Revue des deux mondes (October 15, 1902).
(J. Mo.)
DIDIUS SALVIUS JULIANUS, MARCUS, Roman emperor for two months (March 28-June 2) during the year a.d. 193. He was the grandson of the famous jurist Salvius Julianus (under Hadrian and the Antonines), and the son of a distinguished general, who might have ascended the throne after the death of Antoninus Pius, had not his loyalty to the ruling house prevented him. Didius filled several civil and military offices with distinguished success, but subsequently abandoned himself to dissipation. On the death of Pertinax, the praetorian guards offered the throne to the highest bidder. Flavius Sulpicianus, the father-in-law of Pertinax and praefect of the city, had already made an offer; Didius, urged on by the members of his family, his freedmen and parasites, hurried to the praetorian camp to contend for the prize. He and Sulpicianus bid against each other, and finally the throne was knocked down to Didius. The senate and nobles professed their loyalty; but the people made no attempt to conceal their indignation at this insult to the state, and the armies of Britain, Syria and Illyricum broke out into open revolt. Septimius Severus, the commander of the Pannonian legions, was declared emperor and hastened by forced marches to Italy. Didius, abandoned by the praetorians, was condemned and executed by order of the senate, which at once acknowledged Severus.
Authorities.—Dio Cassius lxxiii. 11-17, who was actually in Rome at the time; Aelius Spartianus, Didius Julianus; Julius Capitolinus, Pertinax; Herodian ii.; Aurelius Victor, De Caesaribus, 19; Zosimus i. 7; Gibbon, Decline and Fall, chap. 5.