I discovered a fascinating puzzle when I was young: A man is getting dressed in the dark. A clothes drawer holds twenty of his socks scattered all about: ten green and ten red. How many socks must he grab, so that when he gets to a place with some light, he can find a matched pair and put those on?
I was too young to object to a man who would wear red or green socks. I probably remember this puzzle because I got it wrong: “eleven,” I thought. If you said “three”, try this puzzle on other people, and be amazed at how often they get it wrong. But what's important about this puzzle, for me, is the lasting influence it has had on my life. I often get dressed in the dark. I have a drawer that frequently holds more than forty socks. I just grab any two of them and put them on. They're all black.