διδάσκων, to teach), signifies the manner of speaking or writing adapted to teach or explain the nature of things.

There are many words which are only used in the didactic and dogmatic way; and there are also many works, ancient and modern, both in prose and verse, written after this method; such as the Georgics of Virgil, Lucretius's poem De Rerum Natura, Pope's Essays on Criticism and on Man, &c.

Diderot, Denis, a French writer and philosopher, was the son of a cutler, and born at Langres in Champagne, in 1713. He received his early education among the Jesuits at the college of that order in his native town, and afterwards at the college D'Harcourt at Paris. At first he was destined for the church, one of his relatives having a canonry to bestow upon him. But he discovered little inclination for the ecclesiastical profession, and his father placed him with an attorney. It soon appeared, however, that he was more attached to a general and desultory pursuit of literature and science than disposed to submit to the drudgeries of the profession to which his father had destined him; and having neglected its duties, his allowance was withheld, and he was obliged to shift for himself. It is said he gave lessons in order to procure a subsistence; and also became a bookseller's hack, in which capacity, we are told, nothing came amiss to him, from an advertisement or a catalogue to a sermon. Certain it is, that the studies to which Diderot devoted his attention were extremely various. Physics, geometry, metaphysics, moral philosophy, and belles-lettres, were at different times the objects of his pursuit; and he even indulged in poetry and works of fiction. But he attached himself chiefly to the graver studies. He possessed great fluency and animation of language in conversation; and this accomplishment, with a decisive tone and manner, procured him both partizans and protectors. The species of reading to which he addicted himself, more various than profound, probably suggested to him those encyclopaedic projects and labours which principally occupied his life, and by which he is chiefly remembered.

In the year 1745 he published L'Essai sur le Merite et la Vertu, 12mo, a work by which he obtained some reputation. The year following he published a piece entitled Pensées Philosophiques, and immediately acquired considerable celebrity. This work, though intrinsically of little merit, was highly commended by the partizans of the new philosophy, amongst whom he had enlisted himself. The same work was afterwards reprinted under the title of Étrennes aux Esprits Forts; it was very much read, and is supposed to have contributed greatly to the diffusion of those free-thinking opinions which had now become so prevalent in France. Soon after this period, Diderot, in conjunction with D'Alembert, concerted the plan of that vast undertaking, the Dictionary Encyclopédique. The professed object of this work was to form a magazine of every branch of human knowledge; it has been also alleged that it was intended by the authors and editors as an engine by means of which those established opinions, whether of a religious or political nature, which they were pleased to suppose had their origin in fraud and superstition, were to be subverted. The department of this work which was intrusted to Diderot was the description of arts and trades (arts et métiers). In fact, he was the principal architect of the edifice; and, besides the Prospectus, and the Système des Connaissances Humaines, which has been much commended for its classification, he contributed many articles in various departments of science. But his articles have been considered extremely verbose and diffuse; in many of them he is pedantically prodigal of metaphysical subtleties, and indulges in a pompous parade of scientific language. The first two volumes of the Dictionary appeared in the year 1751, and the first edition was completed and published in 1765, in 17 vols. fol. and 11 vols. of plates; but although Diderot was occupied in this laborious undertaking for a period of nearly twenty years, the recompense which he obtained for his labours is said to have been extremely small. He himself acknowledged the many defects of the work, not a few of which he attributed to the publisher Le Breton, who, he declared, often played editor himself, scratched out anything which he thought might compromise him, and filled up the chasms as he best could. Diderot's literary labours, however, were not confined to the Dictionary. Just before he commenced, and while engaged upon it, he composed numerous works, amongst which may be mentioned—(1.) Lettres sur les Arègles (1749), "for the use of those who see." This work made a good deal of noise, and, in consequence of some of the sentiments it contained, gave offence to the government, for which reason the author was detained in confinement during several months at Vincennes. (2.) Lettres sur les Sourds et Morts, 2 vols. 12mo, 1751. (3.) The Sixth Sense, which was published in 1752. (4.) Pensées sur l'Interpretation de la Nature, which appeared in 1754. These, which by no means exhaust the list, are similar works, and may be ranked in the same class. Like all his philosophic writings, they are (besides graver defects) often chargeable with the double fault of obscure thoughts expressed in a declamatory style.—His moral character was considerably affected by the publication of Bijoux Indiscrets, in two vols. 12mo, which is a collection of licentious tales; and it was little compensation that his two prose comedies, entitled Le Fils Naturel, 1757, and Le Père de Famille, 1768, comparatively uninteresting as dramatic pieces, exhibit a more correct morality. He also published a pamphlet on Public Education, which contains some useful hints, but at the same time proposes many things utterly absurd and impracticable. To the works now mentioned we may add an eulogy on Richardson, which is full of admiring enthusiasm. An Essay on the Life and Writings of Seneca the Philosopher was his last production, and was published in 1779. For a fuller and tolerably impartial account of these and his other writings, we must refer the reader to the Biographie Universelle.

The character of Diderot suffered considerably from some defamatory attacks which he had made on his former friend Rousseau, who had quarrelled with the French philosophers, and had separated himself from their school. From the Confessions of the philosopher of Geneva, it would appear that they expected of him some anecdotes which would not have reclouded much to their honour. In one of his letters Rousseau, speaking of Diderot, says, "Although Diderot was married and had one daughter; and although he possessed considerable irritability of temper, he was, it is said, a kind husband and a tender parent. His conjugal virtues are not, however, supposed to include fidelity. His sentiments on marriage sufficiently appear in the article on that subject in the Encyclopædia; and his numerous infidelities to his wife, who is said to have been virtuous and affectionate, show how consistently he exemplified them!

At the conclusion of the Dictionary, the state of his affairs having rendered it necessary for him to dispose of his library, it was purchased by the empress of Russia, who, with the king of Prussia, was at that time much given to patronize literature and literary men. These sovereigns were also considered as disciples of the French school. The price which Diderot received for his library was fifteen thousand livres, and he was to have the use of it during his life; or rather Catherine paid him many years' pension in advance, as librarian of his own library. "Elle acheta," says the Biographie Universelle, "en 1765, la bibliothèque de Diderot, pour 15,000 livres, à condition qu'il continuerais d'en jouir. Elle y ajouta une pension annuelle pour l'entretien et la garde de la bibliothèque; et ayant appris, l'année suivante, que le paiement de cette pension avait été retardé, elle lui en fit compter cinquante années." Diderot was so charmed with Catherine's liberality, that he repaired to St Petersburg to express his gratitude; and then, dazzled with his reception, expressed it in terms which sound odd enough in a philosopher of his professed principles. "In a country," he declared, "called a country of slaves, he felt like a freeman." On his return he lodged in state in the Rue Richelieu at Catherine's charge. Diderot had been admitted a member of the Academy of Sciences at Berlin; but the doors of the French Academy remained closed against him to the last. He died suddenly, as he rose from table, on the 30th July 1784. According to his daughter, who left a memoir of him, he conversed on the evening preceding his death on philosophy, and the means of attaining it. She says the last remark she heard him make was, "The first step towards philosophy is incredulity." If so, he had certainly taken that step. Whether he had taken any other may be doubted. His literary and philosophical works were collected and published by his friend and disciple Naigeon, in 15 vols. 8vo, at Paris, in 1798. This collection has been enlarged, in subsequent republications, to 22 vols. 8vo, Paris, 1821; it contains a memoir of Diderot, or rather a critique on his writings.

Diderot, it would seem, had a hand in several of the most remarkable works of his time, published under the names of others. "Who does not know," says Grimm, in his Correspondance, "that nearly a third of the Histoire Philosophique of Raynal belongs to him?" He laboured on it during two years, and a considerable part of it was even composed under my own eyes. Diderot himself was often startled at the boldness with which he had made his friend the abbé speak. "Who," asked he, "who will venture to subscribe this?" "I," replied the abbé, "I will subscribe it; proceed, I tell you." What man of letters is there who may not easily recognise in the book De l'Esprit (of Helvetius), and in the Système de la Nature, all those fine passages which are, and could only be, from the pen of Diderot? If we undertook to make a more complete enumeration, we should run the risk of naming many ungrateful individuals." (Correspondance Littéraire, Philosophique, et Critique, tom. iv. p. 85.) Grimm further states that Diderot furnished a considerable number of pages to the Système de la Nature; and that he laboured, though to a less extent, on the Système Social and the Morale Universelle, also published by Baron d'Holbach. Such were some of the indirect literary efforts of Diderot. But neither as a writer nor as a philosopher did he make for himself any very enviable reputation. As a writer he was decidedly a vicious model; he had neither plan nor connection, and knew not how proprement communiquer dicere, whilst his style was deformed by obscurity, neologisms, and a tone of insufferable dogmatism; nevertheless it must be conceded that he was often vigorous, sometimes eloquent, and now and then stumbled on happy traits of expression; as well as striking truths, which, however, would have gained much by being more simply stated. In fact, he had frequently the air of speaking ex cathedra; his ambitious diction, his strained style, his eccentric sallies, and an enthusiasm which seldom appeared natural, fatigue the reader. As a philosopher he wrote under the influence of a heated imagination rather than under that of cool reason. He was almost always extravagant; seldom or never simple and natural. Admirers, however, have not been wanting who have celebrated his bonheur, his frankness, his easy and obliging character, and the vigour and entroutement of his conversation. Grimm, who has praised him warmly in his Correspondance, regards Diderot as having had the most naturally encyclopaedical head of all men that ever lived. He admires his energy, the variety of his ideas, the multiplicity of his acquirements, the impetuous tumult of his imagination, and the charm and irregularity of his conversation; but he adds, "However willingly I may pardon all men for believing nothing, I think that it would have been very desirable for the reputation of Diderot, perhaps even for the honour of his age, if he had not been an atheist. The determined war which he thought himself obliged to carry on against God, caused him to lose the most precious moments of his life." (Correspondance, 3me partie, tom. iv. p. 87.) But Naigeon, who is less scrupulous than Grimm, praises his friend without qualification, adding, besides, that "his age has not done him justice." It would have been difficult.

The general opinion in regard to him seems now to be pretty well fixed, and posterity has at length put him in his right place. He had talent; but he wanted sagacity, moderation, and taste. "He has written fine pages," says Marmontel in his Memoires, "but he never knew how to make a book." His desolating atheism and licentious principles explain the reason why he never entered the Academy, whose doors, as we have already stated, were constantly shut against him, notwithstanding the anxious desire of his friends to procure him admission. Voltaire, who had himself solicited his election, appears latterly to have become less enamoured of the merit of Diderot, and even to have formally censured some of his works. D'Alembert also cooled towards him, and at last they did not even see each other. His rupture with Rousseau, however, was the work of the latter, who began the war which was afterwards waged between them. But Diderot maintained his connection with Baron d'Holbach, whose sentiments approached the nearest to his own. In the society of the baron he was relished and admired for his facility in general conversation, but especially, no doubt, on account of his antipathy to that creed and to those institutions which that coterie so cordially hated. On these topics he never tired, and his friends often amused themselves with giving him opportunities of abandoning himself to his imagination, or, in other words, blaspheming for their diversion. In an unexcited state he exhibited constraint, awkwardness, timidity, and even a kind of affectation. He was never truly Diderot except when his fancy had transported him as it were beyond himself. Enthusiasm had become the condition most natural to his mind, nay, even to his voice and fea- ture; and he was himself only when in a state of intellectual inebriety. Grimm has reproached him with having consumed in fugitive conversations the time which he might have devoted to more enduring achievements; but Diderot loved to talk, especially when he could indulge his vehement volubility without interruption. As Voltaire once remarked on leaving a company where Diderot had engrossed the whole talk, "Cet homme-là n'est pas propre pour le dialogue." The correspondence recently published has thrown but little new light on the character of this remarkable man, nor has it tended in any degree to increase the estimation in which his talents and character were previously held by the world. He will retain an unenviable notoriety as one of the principal figures in that group of so-called philosophers of the last century who, unable to distinguish between superstition and religion, vainly strove to extinguish religion itself, and entered into an unhallowed conspiracy against the best interests of humanity. Their fantastic theories, licentious maxims, and, too generally, immoral characters, constitute the best antidote to their absurdities, and the best comment on their systems.