An allegory is an extended metaphor, especially a story in which fictional characters and actions are used to understand and express aspects of concepts relating to human existence.
Mish, Frederick (editor). 1991.Webster's ninth new collegiate dictionary. Springfield, MA: Merriam-Webster. 1,564 pages. 0877795088; indexed 0877795096; deluxe 087779510X.
Corbett, Edward P. J. 1971.Classical rhetoric for the modern student. New York: Oxford University.