At a bare minimum, understanding entails being able to detect an internal contradiction: a paradox.
William PoundstoneAre there any mythical beasts which aren't simple pastiches of nature? Centaurs, minotaurs, unicorns, griffons, chimeras, sphinxes, manticores, and the like don't speak well for the human imagination. None is as novel as a kangaroo or starfish.
William Poundstone