When a group of philosophers was recently asked to name the most influential dead thinker, they selected David Hume (runners up: Aristotle, Kant, and Wittgenstein). Selling points for this eighteenth-century Scottish historian and economist include his knack for delivering unsettling ideas—such as naturalism, which robbed the miraculous of its supernatural tenets—in such a genial mode that people hesitated to attack him as a heretic. Anthony Gottlieb, the former executive editor of The Economist, is another deft, congenial writer, and his long-awaited The Dream of Enlightenment (Liveright, $27.95) continues the fascinating exploration he began with his 2001 The Dream of Reason, which gave a fresh and refreshing account of the thought of the ancient Greeks. As he did with the ancients, Gottlieb treats the Enlightenment figures, starting with Descartes, like paintings that have become smudged and muddied by time and fingerprints. He strips away the patina of received ideas, and looks as directly as a historian of ideas can at what these men actually said (all men. As Gottlieb notes, this was only “The Age of Trying to be More Reasonable”). Often, what they first meant isn’t how later audiences have understood it. Was Descartes such a hard-core dualist? Gottlieb shows he wasn’t the “rampant subjectivist” he’s thought to be. And Hobbes—we know him for “nasty, brutish, and short,” but his first and abiding love was geometry. And so on, with Spinoza, Locke, Leibniz, and several French philosophes. Each of Gottlieb’s brief chapters is a masterpiece of brevity and lucidity.