In Douglas Adams’s The Hitchhiker’s Guide to the Galaxy, Deep Thought informs Loonquawl that the meaning of life is 42. Loonquawl exclaims, “Is that all you've got to show for seven and a half million years' work?" Deep Thought replies, “I think the problem, to be quite honest with you, is that you've never actually known what the question is." In much the same way, Americans talk about GDP growth without ever wondering what GDP actually measures. We all know the answer, but most of us don’t know the question.