Parenting, as it turns out, is an extended exercise in being asked questions you are not remotely qualified to answer. My son Joe, at approximately age five, had already raised topics I hadn’t seriously considered until my mid-twenties — including whether the world might be a ball on a giant’s finger, whether there was ever a time when nothing existed (not even space), and whether God makes rules for himself. I did the best I could. Susan did better. This is an essay about what children understand that adults have forgotten.