An allegory is an abstract representation of principles or ideas through the use of characters, figures, or events. It is also the classification for creative work, such as a story or a play, which makes use of allegory. In most cases, allegory is the term used (rather than metaphor) when the symbolic representations reflect an aspect of human behavior or values.
The term allegory originated from the Greek term allegoria (speaking otherwise). It came into common use through plays, generally religious, which would act out human frailties in order to teach a lesson. Characters (often taking the form of animals) would actually be named for their representation. The betrayer would be named “betrayal”, the evil character named “evil” the faithful character named “faith”. The characters had few, if any, characteristics beyond their representation of a concept. These plays were publicly called allegories and were performed at religious gatherings.
Allegories took many forms over the years, such as fables and parables. The story of the tortoise and the hare is an allegory, expressing the belief that the slow and steady will always defeat the quick and prideful in the end.
While the old-time allegories were very direct in showing the audience what represented what, over time allegories became more subtle. In Herman Melville’s Moby Dick, for example, the white whale is seen as an allegory for evil. In Chuck Palahniuk’s Fight Club, the fight clubs are an allegory for modern man’s repressed primal instincts and the need to express them.
Most novels and plays contain some allegorical elements. Symbolic representations of emotions or dilemmas are such a common concept that often writers include them without even realizing they are doing so. Of course, the most masterful of writers are very conscious of the allegories they are creating, even when the allegories seem subtle to the audience.