The spread of the Enlightenment spirit of inquiry and debate owed a great deal to the work of the philosophes (fee-luh-SZOFZ), a group of intellectuals who proudly proclaimed that they, at long last, were bringing the light of reason to their ignorant fellow humans. Philosophe is the French word for “philosopher,” and in the mid-eighteenth century France became a hub of Enlightenment thought.

One of the greatest philosophes, the baron de Montesquieu (mahn-tuhs-KYOO) (1689–1755), pioneered this approach in The Persian Letters, a brilliant and extremely influential social satire published in 1721 and considered the first major work of the French Enlightenment. It consisted of amusing letters supposedly written by two Persian travelers who, as outsiders, saw European customs in unique ways, thereby allowing Montesquieu a vantage point for criticizing existing practices and beliefs.

Having gained fame by using wit as a weapon against cruelty and superstition, Montesquieu set out to apply the critical method to the problem of government in The Spirit of Laws (1748). The result was a complex, comparative study of republics, monarchies, and despotisms. Showing that forms of government were shaped by history and geography, Montesquieu focused on the conditions that would promote liberty and prevent tyranny. He argued for a separation of powers, with political power divided and shared by a variety of classes and legal estates.

The most famous and perhaps most representative philosophe was François Marie Arouet, who was known by the pen name Voltaire (vohl-TAIR) (1694–1778). Early in his career, he was arrested on two occasions for insulting noblemen. Voltaire moved to England for three years in order to avoid a longer prison term in France, and in England he came to share Montesquieu’s enthusiasm for English liberties and institutions.

Returning to France, Voltaire had the great fortune of meeting Gabrielle-Emilie Le Tonnelier de Breteuil, marquise du Châtelet (SHAH-tuh-lay) (1706–1749), a noblewoman with a passion for science. Inviting Voltaire to live in her country house at Cirey in Lorraine and becoming his long-time companion (under the eyes of her tolerant husband), Madame du Châtelet studied physics and mathematics and published scientific articles and translations, including the first — and only — translation of Newton’s Principia into French.)

While living at Cirey, Voltaire wrote works praising England and popularizing English science. He lauded Newton as history’s greatest man because he had used his genius for the benefit of humanity. In the true style of the Enlightenment, Voltaire mixed the glorification of science and reason with an appeal for better individuals and institutions.

Like almost all of the philosophes, however, Voltaire was a reformer, not a revolutionary, in politics. He pessimistically concluded that the best one could hope for in the way of government was a good monarch because human beings “are very rarely worthy to govern themselves.” Nor did Voltaire believe in social and economic equality, insisting that the idea of making servants equal to their masters was “absurd and impossible.” The only realizable equality, Voltaire thought, was that “by which the citizen only depends on the laws which protect the freedom of the feeble against the ambitions of the strong.”3

Voltaire’s philosophical and religious positions were much more radical than his social and political beliefs. In the tradition of Bayle, his writings challenged the Catholic Church and Christian theology at almost every point. Like many eighteenth-century Enlightenment thinkers, Voltaire was a deist, envisioning God as akin to a clockmaker who set the universe in motion and then ceased to intervene in human affairs. Above all, Voltaire and most of the philosophes hated all forms of religious intolerance, which they believed led to fanaticism.

The ultimate strength of the philosophes lay in their dedication and organization. The philosophes felt keenly that they were engaged in a common undertaking that transcended individuals. Their greatest and most representative intellectual achievement was, quite fittingly, a group effort — the seventeen-volume Encyclopedia: The Rational Dictionary of the Sciences, the Arts, and the Crafts, edited by Denis Diderot (DEE-duh-roh) (1713–1784) and Jean le Rond d’Alembert (dah-luhm-BEHR) (1717–1783). Published between 1751 and 1772, it contained seventy-two thousand articles by leading scientists, writers, skilled workers, and progressive priests, and it treated every aspect of life and knowledge. Not every article was daring or original, but the overall effect was little short of revolutionary. Science and the industrial arts were exalted, religion and immortality questioned. Intolerance, legal injustice, and out-of-date social institutions were openly criticized. The encyclopedists were convinced that greater knowledge would result in greater human happiness because knowledge was useful and made possible economic, social, and political progress. Summing up the new worldview of the Enlightenment, the Encyclopedia was widely read, especially in less-expensive reprint editions, and it was extremely influential.