I’ve often thought there ought to be a manual to hand to little kids, telling them what kind of planet they’re on, why they don’t fall off it, how much time they’ve probably got here, how to avoid poison ivy, and so on. I tried to write one once. It was called Welcome to Earth. But I got stuck on explaining why we don’t fall off the planet. Gravity is just a word. It doesn’t explain anything. If I could get past gravity, I’d tell them how we reproduce, how long we’ve been here, apparently, and a little bit about evolution. I didn’t learn until I was in college about all the other cultures, and I should have learned that in the first grade. A first grader should understand that his or her culture isn’t a rational invention; that there are thousands of other cultures and they all work pretty well; that all cultures function on faith rather than truth; that there are lots of alternatives to our own society. Cultural relativity is defensible and attractive. It’s also a source of hope. It means we don’t have to continue this way if we don’t like it.