Holbach , Paul Henri Thyry (or Dietrich) d', baron, a French philosopher, born at Heidels-heim, near Carlsruhe, in 1723, died in Paris, Jan. 21, 1780. He was taken to Paris when very young by his father, from whom he inherited a considerable fortune. A large part of this he expended in hospitalities to the freethinkers of his time, whom he regularly entertained at his splendid table, so that Galiani styled him the premier maitre d'hotel de la philosophic. The boldest opinions and the most irreligious principles were here discussed without restraint. Much information concerning these dinner parties is given in the memoirs of the abbe Morellet, of Mme. d'Epinay, in Grimm's "Correspondence," and in the curious but not impartial work of Mme, de Genlis, Les diners du baron d"Holbach. Holbach attacked with great zeal Christianity and all other positive religions, and labored for the promulgation of naturalistic ideas. He began his literary career by translating a number of German philosophical works. He edited and published in 1750 the works of Boulanger, a young engineer, who died in that year, and afterward published under Boulanger's name his own works, Le Christianisme devoile, ou examen des principes et des effets de la religion revetee (1767), and L'Esprit du clerge, ou le Christianisme primitif venge des entreprises et des exces de nos pretres modernes, which a decree of parliament, Aug. 18, 1770, sentenced to be burned by the public executioner.

The same year he published his most celebrated book, Le systeme de la nature, ou des lois du monde physique et moral, under the fictitious name of Mirabaud, secretaire perpetuel de l'academie frangaise; this created such scandal that Voltaire himself thought proper to refute it in the article Lieu of his Dictionnaire philosophique, while Goethe declared that he recoiled from it in abhorrence as from a "cadaverous spectre." It passed, however, through eight editions between 1817 and 1824, and a new edition in German was published in Leipsic in 1843. In 1772 a short pamphlet, Le bon sens, ou idles naturelles op-posees aux idees surnaturelles, reproduced in a more familiar form the principles he had previously advocated; and this pamphlet, which has been frequently reprinted and largely circulated under the title of L.e Ion sens du cure Meslier, has more powerfully than any other publication contributed to diffuse the principles of infidelity among the middle classes in France. Le systeme social, ou les principes naturels de la morale et de la politique, appeared in 1773, and La morale uniterselle, ou les devoirs de l'homme fondes sur la nature, in 1776. Most of these works were, as soon as they appeared, proscribed by the church and the parliament, and were even disclaimed by philosophers.

All his writings appeared either anonymously, or under the name of deceased persons, or as translations from the English. In his literary performances he had the help of Lagrange, the teacher of his children, of Naigeon, to whose supervision he confided all his works, and of Diderot.