> exceptio probat regulam in casibus non exceptis

Or more succinctly, as first-year law students learn: Expressio unius est exclusio alterius — to state one thing is to implicitly exclude others.

https://definitions.lsd.law/expressio-unius-est-exclusio-alt...

They really mean the same. What changed was the meaning of the word "proves" in English. When the saying was coined it meant "tests", not "confirms". People kept saying the...saying even though they were using it backwards.