An example of an allegory?
An allegory is a tale where the characters and story are generalizations for human existence. An example of this would be a parable as told in the Christian bible.
There is allegory in "A Christmas Carol." Allegory is when there is a reference to the Bible or biblical items in a piece of literature. Allegory in Stave 1 of "A Christmas Carol" is when the narrator is describing all the tiles around Scrooge's fireplace when Scrooge is seeing the face of Marley's ghost.
I am actually writing a paper on this now... an example of an allegory in "The Minister's Black Veil" is the veil itself and how it is symbolic of the sin of the minister and the sin of the people in the town it can also be symbolic of the space that separates one person's soul from everyone else's.