HELVETIUS, LA MET TRIE. 251 experience. The most important instrument in education is the law; the function of the lawgiver is to connect public and personal welfare by means of rewards and punishments, and thus to elevate morality. A man is called virtuous when his stronger passions harmonize with the general interest. Unfortunately the virtues of prejudice, which do not con- tribute to the public good, are more honored among most nations than the political virtues, to which alone real merit belongs. And self-interest is always the one motive to just and generous action ; we serve only our own interests in furthering the welfare of the community. As the promul- gator of these doctrines was himself a kind and generous man, Rousseau could make to him the apt reply : You endeavor in vain to degrade yourself below your own level ; your spirit gives evidence against your principles; your benevolent heart discredits your doctrines. The morality of enlightened self-love or "intelligent self- interest" appears in a milder form in Maupertuis ( ^F(?r>^^, 1752), and Frederick the Great,* to the latter of whom D'Alembert objected by letter that interest could never generate the sense of duty and reverence for the law. 3. Skepticism and Materialism. The ideas thus far developed move in a direction whose further pursuit inevitably issues in materialism. Diderot, the editor of the Encyclopedia of the Sciences, Arts, and Trades (1751-72), which gathered all the currents of the Illumination into one great stream and carried them to the open sea of popular culture, reflects in his intellectual development the dialectical movement from deism through skepticism to atheism and materialism, and was a co- laborer in the work which brought the whole movement to a conclusion, Holbach's System of Nature. Two decades, however, before the latter work, the outcome of a long development of thought, appeared, the physician La Mettrief (1709-51) had promulgated materialism, though
- Essay on Self-love as a Principle of Morals, 1770, printed in the proceed-
ings of the Academy of Sciences. Cf. on Frederick, Ed. Zeller, 1886. f La Mettrie was born at St. Malo, and educated in Paris, and in Leyden under Boerhave ; he died in Berlin, whither Frederick the Great had called him after
