Diderot’s robust faith in nature, that finest fruit of the scientific spirit, comes out again and again, here and elsewhere. “The evil-doer is one whom we must destroy, not punish”: that is the great truth, held by a large number of the foremost men to-day, which is not even yet accepted. “Never to repent and never to reproach others: these are the first steps to wisdom.” And, again: “In the best and most happily constituted man there remains always much of the animal; before becoming a misanthrope, consider whether you have the right.” Not many men have had so much reason as Diderot for becoming misanthropic; few men have had in them less of the misanthrope. “My life is not stolen from me,” he writes; “I give it.... A pleasure which is for myself alone touches me slightly. It is for myself and for my friends that I read, that I reflect, that I write, that I meditate, that I hear, that I observe, that I feel.... I have consecrated to them the use of all my senses, and that is perhaps the reason why everything is a little enriched in my imagination and conversation; sometimes they reproach me, ungrateful as they are. Ungrateful! would I could make hundreds ungrateful every day!” He never seems to waver in his faith in men, nor in the determination, with which, indeed, that faith must ever be bound up, to look every fact of nature squarely in the face. The words with which his letters to Sophie Voland close seem to be the constant refrain throughout all his work: “There is nothing good in this world but that which is true.” It cannot be said that Diderot performed any one great and paramount achievement. The most brilliant of his fragments--the “Rêve de d’Alembert” or “Le Neveu de Rameau”--is but a magnificent improvisation. He made no memorable contribution to our knowledge of the world. Nor was his genius of what may be called the wedge-shaped order--the genius of the man who, with every nerve strained to the solution of one mystery, never rests until the heart of it is cloven. His genius was essentially fermentative. He knew by a native instinct every promising germ of thought, and he knew how to make it fruitful. He was, as Voltaire called him, Pantophile, the man who loved and was interested in everything. His extreme sensitiveness to impressions was the source of his strength and of his weakness. In his sane, massive, and yet so sensitive temperament, aspirations keen and lyrical as Shelley’s seem to blend harmoniously with laughter broad and tolerant as Rabelais’s. The latent elements in him of fantastic extravagance were held in check by a _bourgeois_ good sense in which we seem to recognize the shrewd old cutler of Langres. There is a profound democratic instinct in him; his never-failing faith in nature and man seems to be a part of this; it is a faith that may possibly be foolish, but for all those who are born men it is the most reasonable faith, and it has commended itself most to those who have been oftenest disillusioned.