I apologise for my pedantry, but: > the exception that proves the rule To prove the rule is to test the rule; proof spirit is spirit that passes the test, and

I apologise for my pedantry, but: > the exception that proves the rule To prove the rule is to test the rule; proof spirit is spirit that passes the test, and the proof of the pudding is in the eating. The exception that proves the rule is the exception that violates it (and shows that the rule is a heuristic, not a law).