User blog comment:Flamebiplane/Eziko and Friends (Q&A)/@comment-34552561-20180319230831/@comment-28718853-20180321010537

Eziko ponders Grim's question for a moment, then she snaps her claws and says, "A total paradox! It's assuming that both of these things could exist in the same universe.  It's much like the story involving a fox that could never be caught and a dog that could catch anything.  It's a paradox because both of these scenarios are implausible.  Think about it.  If there was an unstoppable force, then there could be no immovable object.  If there was a dog that could catch anything, then a fox that could never be caught wouldn't exist."