I have been thinking through Thiselton's statement that,
"An allegory therefore presupposes shared understanding; a parable creates shared understanding. There are two further differences. An allegory addresses insiders who are in the know; a parable attacks, or seeks to win over outsiders. Further, it is crucial that on the whole a parable presents an entirely coherent narrative world; an allegory can contain a string of independent applications. Often this is expressed by insisting that a parable has only one point. But although this often follows, it does not always follow, and this view has been attacked" (Anthony C. Thiselton, Hermeneutics: An Introduction [Grand Rapids: Eerdmans, 2009], 38).