In 1872, Ralph Waldo Emerson wrote, «Science does not know its debt to imagination,» words that still ring true in the worlds of health and health care today. The checklists and clinical algorithms of modern medicine leave little space for imagination, and yet we depend on creativity and ingenuity for the advancement of medicine—to diagnose unusual conditions, to innovate treatment, and to make groundbreaking discoveries. We know a great deal about the empirical aspects of medicine,...