If you have, let us say, a theory about man, and if you can only prove it by talking about Plato and George Washington, your theory may be a quite frivolous thing. But if you can prove it by talking about the butler or the postman, then it is serious, because it is universal. So far from it being irreverent to use silly metaphors on serious questions, it is one's duty to use silly metaphors on serious questions. It is the test of one's seriousness. It is the test of a responsible religion or theory whether it can take examples from pots and pans and boots and butter-tubs. It is the test of a good philosophy whether you can defend it grotesquely. It is the test of a good religion whether you can joke about it.