Denying the existence of a deity, and refusing to admit as evidence all a priori arguments, Holbach saw in the universe nothing save matter in spontaneous movement.
For further particulars as to his life and doctrines see Grimm's Correspondance litteraire, &c. (1813); Rousseau's Confessions; Morellet's Memoires (1, 821); Madame de Geniis, Les Diners du Baron Holbach; Madame d'Epinay's Memoires; Avezac-Lavigne, Diderot et la societe du Baron d'Holbach (1875), and Morley's Diderot (1878).
Holbach exposed the logical consequences of the theories of the Encyclopaedists.
Holbach thus worked out the basis of a rigorously materialistic conception of evolution.
In the Systeme social (1 773), the Politique naturelle (1773-1774) and the Morale universelle (1776) Holbach attempts to rear a system of morality in place of the one he had so fiercely attacked, but these later writings had not a tithe of the popularity and influence of his earlier work.
Much of Holbach's fame is due to his intimate connexion with the brilliant coterie of bold thinkers and polished wits whose creed, the new philosophy, is concentrated in the famous Encyclopedie.
The other chief collaborators were Pechmeja, Holbach, Paulze, the farmergeneral of taxes, the Abbe Martin, and Alexandre Deleyre.
The question of human development which Holbach touched on was one which occupied many minds both in and out of France during the 18th century, and more especially towards its close.
The system of Holbach seeks to provide a consistent materialistic view of the world and its processes.