An old favorite.

                       

      Mr. Brain was a hermit dwarf who liked to eat shellfish off the moon.
      He liked to go into a tree then because there is a little height to see a
      little further, which may reveal now the stone, a pebble — it is a twig,
      it is nothing under the moon that you can make sure of.

      So Mr. Brain opened his mouth to let a moonbeam into his head.

     (Russell Edson )