Immanuel Kant (1724–1804), the eminent German philosopher, wrote several influential books, including The Critique of Pure Reason (1781) and Groundwork of the Metaphysics of Morals (1785). Kant held that autonomy, or self-rule, is the mark of a fully mature and moral person, and he believed that the eighteenth-century intellectual movement known as the Enlightenment embodied that ideal. He wrote the following essay, “What Is Enlightenment?” as a newspaper article in 1784 to describe and defend the ideals of the Enlightenment against some of its critics.