The 500 Hats of Bartholomew Cubbins is all about how silly and foolish rules and authority can be. That may seem an odd message to find in a children's book because, well, it is. But trust us. It'll all make sense once we read into the heart of this story.
Most children's books center on informing children how helpful and necessary rules and order are. Listen to your parents; do as you're told; adults are people with authority; the law and lawmakers have you're best interests in mind. Stories like as Aesop's Fables and Grimms' Fairy Tales started the tradition while books like Dick and Jane and The Berenstain Bears have kept it going strong.