Jonathan Israel presents the first major reassessment of the Western Enlightenment for a generation. Continuing the story he began in the best-selling Radical Enlightenment, and now focusing his attention on the first half of the eighteenth century, he returns to the original sources to offer a groundbreaking new perspective on the nature and development of the most important currents in modern thought.

Israel traces many of the core principles of Western modernity to their roots in the social, political, and philosophical ferment of this period: the primacy of reason, democracy,...