In 1784 a Berlin newspaper invited responses to the now-familiar question “What is Enlightenment?” Immanuel Kant’s reply retained the question as its title: a choice which has contributed to the sense that the question has, always, already been answered. But we keep asking it, and Kant’s “What is Enlightenment?” now ranks high among often cited and rarely read texts of the Western canon. It contains some dependable platitudes concerning free expression, as well as the exhortation “Sapere aude!” (“Dare to know!”), frequently taken as the most succinct version of his answer. “Dare to Know: Prints and Drawings in the Age of Enlightenment” at the Harvard Art Museums brought together 150 prints, drawings, and books in order to examine how images contributed to the production and dissemination of Enlightenment knowledge between roughly 1720 and 1800. The accompanying catalog is an homage to Diderot and D’Alembert’s Encyclopédie (1751-72), with twenty-six alphabetically arranged articles on topics that shape our own understanding of eighteenth-century thought. According to Elizabeth Rudy and Tamar Mayer’s entry on “Time,” the very act of looking backward as a mode of inquiry is an intellectual operation that would not be possible without the notion of history that emerged in this …