Pierre Bayle (1647-1706) is most famous for his Historical and Critical Dictionary(1697), which Thomas Jefferson later considered one of the 100 works essential to higher education. In the excerpt below from Bayle's Philosophical Commentary on the Words of Jesus Christ (1686-1687), Bayle responded to Louis XIV’s Revocation of the Edict of Nantes with the argument that intolerance caused the very kinds of political problems that Louis hoped to solve. Bayle advocated religious toleration more thoroughly and with a more sophisticated argument than did, for example, John Locke, for whom tolerance could not be extended to atheists or Catholics. For Bayle, by contrast, not only should all shades of belief (including atheism) be tolerated, but indeed, a state will be stronger in proportion to the religious, intellectual, and cultural diversity it contains. Bayle himself was probably a skeptic, although historians still argue about whether or not he may have been a sincere Christian despite his obvious disdain for religious hypocrisy. Bayle's brother, a Calvinist minister, was killed by French authorities in the wake of the Revocation of the Edict of Nantes. Bayle himself managed to escape to safety in Holland, from whence, in his writings, he ushered in the age of Enlightenment.

In this work, John Locke (1632-1704) advises his friend, Sir Edward Clarke, on how to educate his son. Some Thoughts Concerning Education was originally intended, then, as a private communication. However, the work soon became a prominent and popular example of advice manuals on child-rearing and education, which was a burgeoning literature in eighteenth-century Europe. Indeed, while Locke held the common people in some disdain, and he authored his advice with the son of an aristocrat in mind, his views were later adopted and transformed by other pedagogues with broader views of human potential. Locke, in any case, emphasizes the importance of environment and conditioning in the formation of youthful character and capacity, views that may well be taken for granted today, but which struck some of Locke's critics as underestimating the power of such allegedly innate traits as "ideas" or "original sin."

British poet Alexander Pope (1688-1744) provides, in his Essay on Man, a poetic summary of his own answer to the question Kant would later ask and treat in philsophical prose, "What is enlightenment?" Pope's mixture of optimism about and frustration with human nature permeated the struggle of eighteenth century European thinkers to imagine how, in practical terms, a better society could be constructed by human hands. Pope's remark that "the proper study of mankind is man" is suggestive, for many scholars argue that the very essence of the Enlightenment itself was the drive to free humanity from deference to and dependence upon traditional belief systems and socio-political arrangements as if they were divinely ordained.

In The Persian Letters, Montesquieu (1689-1755) made use of Europe's growing knowledge of the Middle East and its history in order to craft a critique of the state of affairs in Europe--especially in France. The document selected here reveals both Montesquieu's effort at a sympathetic treatment of the Persians themselves and a criticism of the tangled controversies and strife in French history in which religion and politics were inextricably intertwined. In this document, for example, Montesquieu offers a rather thinly-veiled suggestion that Louis XIV’s Revocation of the Edict of Nantes (1685) was an absurd act of self-destruction that his ancestor Henry IV, the author of the Edict of Nantes (1598), would never have stood for.

In The Social Contract, Jean-Jacques Rousseau (1712-1778) expounded his vision of the basic principles of political society. Rousseau's political theory is based to some extent upon a conjectural history of what primitive human societies must have been like. Rousseau was quite interested in reading ethnographic accounts of exotic societies during his lifetime. Nonetheless, his arguments may have been based even more on a view of human nature as, ultimately, a unitary essence that transcends the many divergencies between various cultures. In any case, his conjectural history suggests that, sooner or later, all primitive societies must confront the problems which, for Rousseau, only the social contract could successfully resolve. Hence, in the long run of history, for Rousseau all people must sooner or later be "forced to be free."

Voltaire was the assumed name of François-Marie Arouet (1694-1778). In a lengthy career, he wrote more than seventy volumes, traveled extensively (often to escape arrest), and communicated with royalty. Among his many achievements, Voltaire helped to popularize English scientific progress and proclaimed Isaac Newton as history’s greatest man. In his own work, Voltaire wrote about government, philosophy, religion, and human nature, themes that appear most clearly in his masterpiece, Candide. When it first appeared in 1759, his work became an instant bestseller, and it has taken its place as one of the key texts of the Enlightenment. Written after Voltaire’s observations of the 1755 Lisbon earthquake, Candide traces the life of the title character as he travels throughout the world. Voltaire uses Candide’s adventures as a means to comment on the philosophies of his day. The following selection is taken from the first chapter.

Denis Diderot's (1713-1784) Encyclopedia represents one of the most important intellectual achievements of the Enlightenment. Begun in 1751, the collection included articles by Voltaire, Montesquieu, Rousseau, and others on topics such as atheism, science, and religion. The monumental project was finished in 1765, and it appropriately sums up many of the ideas of the Enlightenment. This image is a fascimile of the frontispiece of the Encyclopedia, and it shows an allegory of Truth dispersing the shadows of ignorance.

Born in Dessau, Germany, Moses Mendelssohn (1729-1786) became a vociferous advocate of toleration in a world where anti-Semitism flourished. A practicing Jew, Mendelssohn sought to marry his faith with the Enlightenment ideas of the time. In his work, Jerusalem: Or on Religious Power and Judaism, from which the following selection is taken, he argued that states should respect all religions, while refraining from exercising power over private beliefs.

Gotthold Ephraim Lessing (1729-1781) was the son of a Lutheran pastor. Lessing was troubled by certain elements in traditional Christian doctrine, but even more by the apparent refusal of church authorities and theologians to grapple with what he regarded as serious challenges to the Christian faith. In the final years of his life, he fomented a great theological controversy, which centered on the question of the historical reliability of the biblical texts. Lessing also wrestled with the philosophical problem of attributing eternal significance to an historical event (the Incarnation), which could not be proven to have occurred, and which seemed even to fly in the face of reason. Nonetheless, Lessing was (and perhaps is) best known as a playwright and literary critic. In his play Nathan the Wise, Lessing sought not only to urge tolerance between Christians, Jews, and Muslims, but even to suggest that the three religions, like the three rings of the play, were basically indistinguishable if one simply examined the ethical essence of their teachings. Some scholars have argued that Lessing used the medium of fiction to convey his controversial message(s), a claim that seems likely as he was ordered by government officials in the 1770s to refrain from publishing any theological works.

In the following essay, German philosopher Immanuel Kant (1724-1804) attempts to summarize the goals and achievements of the Enlightenment. For Kant, "enlightenment" is a process that has only just begun. And indeed, some scholars think that we are still living in the shadow of the eighteenth century. They argue that the fundamental social and human issues with which Kant and his contemporaries wrestled are, at base, the same ones that confront us today. Others, of course, disagree with this view. Most agree, however, that Kant provides a reasonably accurate summary of the aspirations of eighteenth-century European intellectuals.

Peter Gay interprets the Enlightenment as a coherent and evolving system of thought. For Gay, Enlightenment thinkers were united in their firm rejection of the traditional religion of western civilization, Christianity.