"The answer that came to me again and again was play. Every human society in recorded history has games. We don't just solve problems out of necessity. We do it for fun. Even as adults. Leave a human being alone with a knotted rope and they will unravel it. Leave a human being alone with blocks and they will build something. Games are part of what makes us human. We see the world as a mystery, a puzzle, because we've always been a species of problem-solvers."