Babel fish are small, yellow and leech-like, and possibly the oddest thing in the Universe. They feed on brainwave energy not from their carrier but from those around it. They absorb all unconscious mental frequencies from this
brainwave energy to nourish itself with and then excrete into the mind of their carrier a telepathic matrix formed by combining the conscious thought frequencies with nerve signals picked up from the speech centers of the brain which has supplied them.
The practical upshot of all this is that if you stick a Babel fish in your ear you can instantly understand anything said to you in any form of language. The speech patterns you actually hear decode the brainwave matrix which has been fed into your mind by your Babel fish. This, added to the fact that there is no need to feed them, makes them much more practical and reliable than most universal translators but consequently also much more expensive.
Now it is such a bizarrely improbable coincidence that anything so mindboggingly useful could have evolved purely by chance that some thinkers have chosen to see it as the final and clinching proof of the non-existence of God. 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. Most leading theologians claim that this argument is a load of dingo's kidneys, but that didn't stop Oolon Colluphid making a small fortune when he used it as the central theme of his bestselling book Well, That About Wraps if up for God.
Meanwhile, the poor Babel fish, by effectively removing all barriers to communication between different races and cultures, has caused more and bloodier wars than anything else in the history of creation