There’s an old saying that life is school. If that’s true, then it’s also true that as our world grows smaller and the people in it more inextricably connected, the world itself comes to resemble one vast, inclusive schoolhouse. There are younger people and older people, people farther or less far along in their education on a given subject. At every moment, we are both students and teachers; we learn by studying, but we also learn by helping others, by sharing and explaining what we know.