al-lu-sion An instance of indirect reference: an allusion to classical mythology in a poem. A figurative or symbolical reference. a-nal-o-gy A resemblance of relations; an agreement or likeness between things in some circumstances or effects, when the things are otherwise entirely different. A figurative or symbolical reference. al-le-go-ry The representation of abstract ideas or principles by characters, figures, or events in narrative, dramatic, or pictorial form. A story, picture, or play employing such representation. John Bunyan's The Pilgrim's Progress and Herman Melville's Moby-Dick or, The Whale are allegories. A symbolic representation: The blindfolded figure with scales is an allegory of justice. A figurative sentence or discourse, in which the principal subject is described by another subject resembling it in its properties and circumstances. The real subject is thus kept out of view, and we are left to collect the intentions of the writer or speaker by the resemblance of the secondary to the primary subject.

Starting with a great story--classical, biblical, mythological, Shakespearean, etc.--gives you a time-tested foundation for your movie. Consciously or subconsciously it will more powerfully engage your readers and audience. Besides being easier to sell, it gives you an opportunity to read the books you knew you should be reading anyway in order to become a great writer.