In T.S. Eliot's, Tradition and the Individual Talent, he believes that there is no such thing as original thought. All ideas have to come from somewhere, but everything else is a copy. I good example of this is Hollywood. The story line is typically- he gets the girl, he loses the girl, and he gets the girl at the end. Another story line is that the hero always saves the day...and lives. If the story ever ends differently, the audience gets upset because we are used to the same thing. Over and over again.
"If you're gonna be original, you can count on being copied."