This title challenges the belief that the 18th century was essentially modern in its temper. Carl Becker demonstrates that the period commonly described as the Age of Reason was, in fact, very far from that; that Voltaire, Hume, Diderot, and Locke were living in a medieval world, and that these philosophers "demolished the Heavenly City of St. Augustine only to rebuild it with more up-to-date materials". In a new foreword, Johnson Kent Wright looks at the book's continuing relevance within the context of current discussion about the Enlightenment.