From The Hitchhikers guide to the Galaxy
The Babel fish is small, yellow and leech-like, and probably the oddest thing in the Universe. It feeds on brainwave energy received not from its own carrier but from those around it, It absorbs all unconscious mental frequencies from this brainwave energy to nourish itself with. the practical upshot of this is that if you stick a Babel fish in your ear you can instantly understand anything said to you in any language.
Now it is such a bizarrely improbable coincidence that anything so mind-bogglingly useful could have evolved purely by chance that some thinkers have chosen to see as a final and clinching proof of the non-existence of God. The argument goes 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.
