" The whole book is about how we should try to find rules other people can't reasonably reject, and then he ends it by saying, "The search for how to find these rules will go on forever." I proposed a rule that Chidis shouldn't be allowed to leave because it would make Eleanors sad. And I could do this forever, zip you around the universe showing you cool stuff... and I'd still never find the justification for getting you to stay. Because it's a selfish rule. I owe it to you to let you go. "