The Great Recession was supposed to clobber New York, but the city is doing just fine. Its unemployment rate is below the national average. Per-capita earnings in the New York metropolitan area remain 40% above the American metropolitan average. Housing prices have declined less than they have almost anywhere else. How has New York remained so strong? The secret to the city’s enduring strength is not a specific industry or a political leader but rather its unequaled ability to bring millions of people together and enable them to educate each other. Humanity’s greatest gift is our ability to learn from...