Tristan McLeay wrote: > The expression is 'the exception that proves the rule', and harkens back > to an older meaning of 'prove' and 'proof' of 'test'. Though along with > the changed definition of 'prove', the saying's been misanalysed as > meaning what you said. As others have pointed out, this is wrong, although it's a common myth. The original meaning is that if there's a legal principle which states, for example, that it is permissable to throw paper aeroplanes in the classroom between 10:00 and 10:30 am, then this is evidence that there's an implicit legal principle to the effect that paper aeroplanes may not be thrown in the classroom when the exception is not applicable. (I've chosen a silly example because that's more fun.) Adrian.