HOLBACH, PAUL HEINRICH DIETRICH, BARON D' (1723-1789), French philosopher and man of letters, of German origin, was born at Heidelsheim in the Palatinate. Holbach kept open house in Paris for Helvetius, D'Alembert, Diderot, Con dillac, Turgot, Buffon, Grimm, Hume, Garrick, Wilkes, Sterne, and for a time J. J. Rousseau. For the great Encyclopedie he compiled and translated a large number of articles on chemistry and mineralogy, chiefly from German sources. In 1767 Christian isme devoile appeared, in which he attacked Christianity and re ligion as the source of all human evils. This was followed up by other works, and in 1770 by a still more open attack in his most famous book, Le Systeme de la nature, in which he was probably assisted by Diderot. Denying the existence of a deity, and refus ing to admit as evidence all a priori arguments, Holbach saw in the universe nothing save matter in spontaneous movement. What men call their souls become extinct when the body dies. Happi ness is the end of mankind. "It would be useless and almost un just to insist upon a man's being virtuous if he cannot be so with out being unhappy. So long as vice renders him happy, he should love vice." Not less direct and trenchant are his attacks on political government, which, interpreted by the light of of ter events, sound like the first distant mutterings of revolution. Hol bach exposed the logical consequences of the theories of the En cyclopaedists. Voltaire hastily seized his pen to refute the philos ophy of the Systeme in the article "Dieu" in his Dictionnaire phil osophique, while Frederick the Great also drew up an answer to it. Though in some passages clear and eloquent, the style of the Systeme is diffuse and declamatory, and asserts rather than proves its statements. Its principles are summed up in a more popular form in Bon Sens, ou idees naturelles opposees aux idees sur naturelles (Amsterdam, 1772). In the Systeme social (1773), the Politique naturelle and the Morale universelle (1776) Holbach attempts to rear a system of morality in place of the one he had so fiercely attacked, but none of his later writings had a tithe of the popularity and influence of his earlier work. J. J. Rousseau is supposed to have drawn his portrait in the virtuous atheist Wolmar of the Nouvelle Heloise. He died on Jan. 21, 1789.
For further -particulars as to his life and doctrines see Grimm's Correspondance litteraire, etc. (1813) ; Rousseau's Confessions; Morellet's Memoires (1821) ; Madame de Genlis, Les Diners du Baron Holbach; Madame d'Lpinay's Memoires; Avezac-Lavigne, Diderot et la societe du Baron d'Holbach (1875) ; T. Morley, Diderot (1878) ; N. P. Cushing, Baron d'Holbach (1914) ; R. Hubert, D'Holbach et ses Amis (1928) .