Cudgel thy brains no more about it, for your dull ass will not mend his pace with beating.
– William Shakespeare
Hamlet, Act 5, Scene 1. As the two gravediggers prepare a grave for Ophelia, they lighten up their work with riddles. Here the First Gravedigger, in a humorous put-down, tells the Second Gravedigger not to beat up his slow brains and compares his brain to a slow donkey.