En réponse à Jan van Steenbergen :

>"De uitzondering, die de regel bevestigt". Confirm and nothing else!

Since in so many different languages it's "confirm" rather than "prove" 
(IIRC so it is in Italian, Spanish and Portuguese - Jan, what about Polish? 
and maybe Russian? -), I'd rather think that the use of "prove" in the 
English expression is the exception rather than the rule here. And as I 
said before, "confirm" makes much more sense than "prove" anyway (the 
correct origin of the expression indeed maps quite well my description with 

Christophe Grandsire.

You need a straight mind to invent a twisted conlang.