I remember that one time Carl Sagan was giving a talk, and he spelled out, in a kind of withering succession, these great theories of demotion that science has dealt us, all of the ways in which science is telling us we are not who we would like to believe we are. At the end of it, a young man came up to him and he said: "What do you give us in return? Now that you've taken everything from us? What meaning is left, if everything that I've been taught since I was a child turns out to be untrue?" Carl looked at him and said, Do something meaningful.