The Dictionnaire Philosophique is Voltaire’s principal essay in philosophy, though not a sustained work. The miscellaneous articles he contributed to Diderot’s Encyclopédie which compose this Dictionary embody a mass of scholarly research, criticism, and speculation, lit up with pungent sallies at the formal and tyrannous ecclesiasticism of the period and the bases of belief on which it stood.

These short studies reflect every phase of Voltaire’s sparkling genius. Though some of the views enunciated in them are now universally held, and others have become obsolete through extended knowledge, they were startlingly new when Voltaire, at peril of freedom and reputation, spread them before the people of all civilized nations, who read them still with their first charm of style and substance.