One of my more memorable exchanges with a student came in a principles of economics class. Part of the assignment for that week was chapters from Matt Ridley’s The Rational Optimist. Ridley compared the living standards of an average worker today with those of The Sun King, Louis XIV, in 1700. Some of my more ahistorical students were incredulous at Ridley’s description of the grinding poverty of the average person just a few centuries ago. The King had an opulent lifestyle compared to others. Louis had an astonishing 498 workers preparing each of his meals. Yet his standard of living...