Quod erat demonstrandum

The JC’s guide to pithy Latin adages


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Quod erat demonstrandum”. A jolly good Latin expression, meaning “the very thing that you were trying to prove”; to be used when you are trying to show off, seem articulate or be witty. But steer clear of it if you are trying to inform, because, Q.E.D., those without a classical education won’t understand it and may grow restive.

But it was in the Hitch-Hiker’s Guide to the Galaxy.

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 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. Q.E.D..”
“Oh dear,” says God, “I hadn’t thought of that,” and promptly vanishes in a puff of logic.

Also, my secret Latin advisor tells me, “demonstrandum” is a gerundive. Which is nice.