Once you know the idea behind your story, it’s time to weave that idea into the plot. And one of the more common methods is to create an outline, either before or after writing a rough draft. Outlines help us see the big picture, see how the individual scenes are themselves part of a larger pattern, and it’s often on that larger scale that the idea emerges as the meaning of the story.
Start with a topic, something that interests you. Philosophy can be a great source.
Whether you call it the moral, message, or theme, every story has an underlying meaning or idea. Most stories engage either moral and/or philosophical questions, which the plot demonstrates through a series of relatable situations.
How is it that some stories endure far beyond the lifetime of their author? Shakespeare is a prime example. His plays not only endure, they adapt to modern settings, and yet people still recognize Romeo and Juliet even when it’s called West Side Story because the idea behind it is unchanged. Ideas are the questions the story raises, and the answers it chooses to provide. In Romeo and Juliet the idea centers around two people who wish to be together, but social/cultural forces oppose them, man vs. society.