An idea or meaning when added to a story adds value and memorably, to the reading experience. For instance everyone can remember the childhood story about the "Little Engine That Could." From that simplistic writing and simplistic short children forever remember the theme of that story, never give up. Had that story lacked a theme the story would be meaningless. A theme also can change or create a moral standpoint for the reader. For instance in the now famous novel "The Lord of the Rings" the theme is a moral one, never allow evil to prevail. …
