In his famous and wonderfully heartening letter of fatherly advice, F. Scott Fitzgerald gave his young daughter Scottie a list of things to worry and not worry about in life. Among the unworriables, he named popular opinion, the past, the future, triumph, and failure “unless it comes through your own fault.” Among the worry-worthy, courage, cleanliness, and efficiency. What Fitzgerald touched on, of course, is the quintessential anxiety of the human condition, which drives us to worry about things big and small, mundane and monumental, often confusing the two classes. It was this “worryability” that young Italo Calvino resolved to shake from his life. A wonderful 1934 book classified all of our worries in five general categories that endure with astounding prescience and precision, but we still struggle to identify the things truly worth worrying about — and, implicitly, working to resolve — versus those that only strain our psychoemotional capacity with the deathly grip of anxiety.