His views on education, chiefly expressed in the “Plan d’une Université pour le Gouvernement de Russie,” are on a level with the most advanced views to-day. The education he demands is free and compulsory, and he is in favour of giving children free meals at school. He censures classical teaching, advocates professional education and instruction in the natural sciences, “the study of things rather than the study of words.” “I think,” he says, “that we should give in our schools something of all the knowledge necessary to a citizen, from legislation to the mechanical arts, and in these mechanical arts I include the occupations of the lowest class of citizens. The spectacle of human industry is in itself large and satisfying, and it is good to know the different ways in which each contributes to the advantages of society. This kind of knowledge is attractive to children, who are naturally inquisitive.” Certainly, from more than one point of view, such an element in education would have an important social significance. Of the functions and position of women--in most countries, he remarks, that of idiot children--he speaks often, shrewdly indeed, yet with peculiar sympathy. The most important expression of his opinions on sexual morality is contained in the “Supplément au Voyage de Bougainville.” Bougainville, the first Frenchman to sail round the world, had visited the lovely island of Tahiti, and brought back a strange and vivid picture of the idyllic innocence and frank license that existed there. Diderot was aroused to set forth his views on sexual questions with that union of fiery enthusiasm, uncompromising thoroughness, and saving grace of humorous good sense which always characterizes him. He imagines a dialogue between the chaplain of Bougainville’s expedition and Orou, a Tahitian, who is anxious to know why the chaplain refuses to conform to the customs of the country. The worthy chaplain represents the morality of civilized Europe, and Orou, with a few questions concerning this morality, easily succeeds in confounding him and in pouring keen ridicule on the inconsistencies of European morals. With reference to rules of conduct which vary with the country and the time, Diderot makes Orou say, “We must have a surer rule, and what shall this rule be? Do you know any other than the good of the community and the advantage of the individual?” “You were unhappy,” he remarks again to the chaplain, “when I presented to you last night my two daughters and my wife; you exclaimed, ‘But my religion! my office!’ Do you wish to know what in every time and place is good and bad? Concern yourself with the nature of things and of actions, and with your relations to your fellows. Consider the influence of your conduct on yourself and on the community. You are mad if you think that there is anything in the universe, above or below, which can add to or take from the laws of nature.” That rule,