This should look a little familiar, but there’s a twist:
Literally: empty – before – cut off – after
Alternately: Unique in all of history. Never before, and never again. Something so amazing, or so horrible, that the like of it is unheard-of in the past… and furthermore, it’s not likely to ever be repeated. If you’re talking about something in the past, then perhaps it’s something that was unprecedented at the time and hasn’t been reproduced yet.