"The argument goes something like this: 'I refuse to prove that I exist,' says God, 'for proof denies faith, and without faith I am nothing.' " 'But,' says Man, 'the Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED.' " 'Oh dear,' says God, 'I hadn't thought of that,' and promptly vanishes in a puff of logic. " 'Oh, that was easy,' says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing."