This book features the most significant aspects of life and work of Denis Diderot (1713-1784), French philosopher, art critic, and writer, who is best known for serving as co-founder, chief editor, and contributor to the Encyclopédie. Diderot was a prominent figure during the Age of Enlightenment. In the 1740s he wrote many of his best-known works in both fiction and non-fiction, including the 1748 novel The Indiscreet Jewels. In 1751, Diderot co-created the Encyclopédie with Jean le Rond d'Alembert. The Encyclopédie is most famous for representing the thought of the Enlightenment. Its contributors advocated for the secularization of learning away from the Jesuits. Diderot wanted to incorporate all of the world's knowledge into the Encyclopédie and hoped that the text could disseminate all this information to the public and future generations. It was also the first encyclopedia to include contributions from many named contributors and the first to describe the mechanical arts. Its secular tone, which included articles skeptical about Biblical miracles, angered both religious and government authorities; in 1758 it was banned by the Catholic Church and in 1759 the French government banned it as well, although this ban was not strictly enforced. Many of the initial contributors to the Encyclopédie left the project as a result of its controversies and some were even jailed. D'Alembert left in 1759, making Diderot the sole editor. Diderot also became the main contributor, writing around 7,000 articles. He continued working on the project until 1765. The Encyclopédie is often considered an influence and one of the forerunners of the French Revolution because of its emphasis on Enlightenment political theories.

John Morley (1838-1923) was a British Liberal statesman, writer and newspaper editor. He devoted a considerable amount of time to literature. Morley's position as a leading British writer had early been determined by his monographs on Voltaire (1872), Rousseau (1873), Diderot and the Encyclopaedists (1878), Burke (1879), and Walpole (1889). His contributions to political journalism and to literary, ethical and philosophical criticism were numerous and valuable.