A sappy lesson I remember learning over and over in various cartoons as a child; an analogous metaphor we've all heard is, "Don't judge a book by its cover." However, as opposed to books, people cannot simply open up a human's thoughts and feelings and read them at their leisure. "What's on the inside" can only be revealed to the outside through making those thoughts visible to the world. Although thoughts and feelings are most generally conveyed through words, they are certainly adaptable to appearance as well: this is why people buy tye-dye shirts, or shirts from The Onion that simply say You Are Dumb.