Voltaire and Rousseau were the heads of two important schools, and each of them set deep and unmistakable marks both on the opinion and the events of the century. It would not be difficult to show that their influence was wider than that of the philosopher who discerned the inadequateness of both. But Rousseau was moved by passion and sentiment; Voltaire was only the master of a brilliant and penetrating rationalism. Diderot alone of this famous trio had in his mind the idea of scientific method; alone showed any feeling for a doctrine, and for large organic and constructive conceptions. He had the rare faculty of true philosophic meditation. Though immeasurably inferior both to Voltaire and Rousseau in gifts of literary expression, he was as far their superior in breadth and reality of artistic principle. He was the originator of a natural, realistic, and sympathetic school of literary criticism. He aspired to impose new forms upon the drama. Both in imaginative creation and in criticism, his work was a constant appeal from the artificial conventions of the classic schools to the actualities of common life. The same spirit united with the tendency of his philosophy to place him among the very few men who have been great and genuine observers of human nature and human existence. So singular and widely active a genius may well interest us, even apart from the important place that he holds in the history of literature and opinion.

CHAPTER II.
YOUTH.

Denis Diderot was born at Langres in 1713, being thus a few months younger than Rousseau (1712), nearly twenty years younger than Voltaire (1694), nearly two years younger than Hume (1711), and eleven years older than Kant (1724). His stock was ancient and of good repute. The family had been engaged in the great local industry, the manufacture of cutlery, for no less than two centuries in direct line. Diderot liked to dwell on the historic prowess of his town, from the days of Julius Cæsar and the old Lingones and Sabinus, down to the time of the Great Monarch. With the taste of his generation for tracing moral qualities to a climatic source, he explained a certain vivacity and mobility in the people of his district by the great frequency and violence of its atmospheric changes from hot to cold, from calm to storm, from rain to sunshine. "Thus they learn from earliest infancy to turn to every wind. The man of Langres has a head on his shoulders like the weathercock at the top of the church spire. It is never fixed at one point; if it returns to the point it has left, it is not to stop there. With an amazing rapidity in their movements, their desires, their plans, their fancies, their ideas, they are cumbrous in speech. For myself, I belong to my country side." This was thoroughly true. He inherited all the versatility of his compatriots, all their swift impetuosity, and something of their want of dexterity in expression.

His father was one of the bravest, most upright, most patient, most sensible of men. Diderot never ceased to regret that the old man's portrait had not been taken with his apron on, his spectacles pushed up, and a hand on the grinder's wheel. After his death, none of his neighbours could speak of him to his son without tears in their eyes. Diderot, wild and irregular as were his earlier days, had always a true affection for his father. "One of the sweetest moments of my life," he once said, "was more than thirty years ago, and I remember it as if it were yesterday, when my father saw me coming home from school, my arms laden with the prizes I had carried off, and my shoulders burdened with the wreaths they had given me, which were too big for my brow and had slipped over my head. As soon as he caught sight of me some way off, he threw down his work, hurried to the door to meet me, and fell a-weeping. It is a fine sight—a grave and sterling man melted to tears."[1] Of his mother we know less. He had a sister, who seems to have possessed the rough material of his own qualities. He describes her as "lively, active, cheerful, decided, prompt to take offence, slow to come round again, without much care for present or future, never willing to be imposed on by people or circumstance; free in her ways, still more free in her talk; she is a sort of Diogenes in petticoats.... She is the most original and the most strongly-marked creature I know; she is goodness itself, but with a peculiar physiognomy."[2] His only brother showed some of the same native stuff, but of thinner and sourer quality. He became an abbé and a saint, peevish, umbrageous, and as excessively devout as his more famous brother was excessively the opposite. "He would have been a good friend and a good brother," wrote Diderot, "if religion had not bidden him trample under foot such poor weaknesses as these. He is a good Christian, who proves to me every minute of the day how much better it would be to be a good man. He shows that what they call evangelical perfection is only the mischievous art of stifling nature, which would most likely have spoken as lustily in him as in me."[3]

Diderot, like so many others of the eighteenth-century reformers, was a pupil of the Jesuits. An ardent, impetuous, over-genial temperament was the cause of frequent irregularities in conduct. But his quick and active understanding overcame all obstacles. His teachers, ever wisely on the alert for superior capacity, hoped to enlist his talents in the Order. Either they or he planned his escape from home, but his father got to hear of it. "My grandfather," says Diderot's daughter, "kept the profoundest silence, but as he went off to bed took with him the keys of the yard door." When he heard his son going downstairs, he presented himself before him, and asked whither he was bound at twelve o'clock at night. "To Paris," replied the youth, "where I am to join the Jesuits." "That will not be to-night; but your wishes shall be fulfilled. First let us have our sleep." The next morning his father took two places in the coach, and carried him to Paris to the Collége d'Harcourt. He made all the arrangements, and wished his son good-bye. But the good man loved the boy too dearly to leave him without being quite at ease how he would fare; he had the patience to remain a whole fortnight, killing the time and half dead of weariness in an inn, without ever seeing the one object of his stay. At the end of the fortnight he went to the college, and Diderot used many a time to say that such a mark of tenderness and goodness would have made him go to the other end of the world if his father had required it. "My friend," said his father, "I am come to see if you are well, if you are satisfied with your superiors, with your food, with your companions, and with yourself. If you are not well or not happy, we will go back together to your mother. If you had rather stay where you are, I am come to give you a word, to embrace you, and to leave you my blessing." The boy declared he was perfectly happy; and the principal pronounced him an excellent scholar, though already promising to be a troublesome one.[4]

After a couple of years the young Diderot, like other sons of Adam, had to think of earning his bread. The usual struggle followed between youthful genius and old prudence. His father, who was a man of substance, gave him his