Here’s the problem with symbols: people expect them to mean something. Not just any something, but one something in particular…It doesn’t work like that. Oh, sure, there are some symbols that work straightforwardly: a white flag means, I give up, don’t shoot. Or it means, We come in peace. See? Even in a fairly clear-cut case we can’t pin down a single meaning, although they’re pretty close. So some symbols do have a relatively limited range of meanings, but in general a symbol can’t be reduced to standing for only one thing.

If they can, it’s not symbolism, it’s allegory. Here’s how allegory works: things stand for other things on a one-for-one basis.

[…]

[With symbols, however,] the thing referred to is likely not reducible to a single statement but will more probably involve a range of possible meanings and interpretations. [A symbol requires] of us…to bring something of ourselves to the encounter [in order to get its meaning].

How To Read Literature Like A Professor by Thomas C. Foster

What Does Allegory Mean?

Allegorical means, among many other things, that the characters, worlds, actions and objects are, of necessity, highly metaphorical. That doesn’t mean they aren’t unique or created by the writer. It means the symbols have references that echo against previous symbols, often deep in the audience’s mind.

Allegorical also means ‘applicable to our modern world and time’.

Good stories have elements that are founded on the thematic line and oppositions. This especially applies to allegory. For example, for Tolkien, Christian thematic structure emphasises good versus evil.

— John Truby, Anatomy of Story

Features Of Allegory

SUBTEXT

Like a theme story, allegory has a subtext, a pattern of meaning beyond what’s evident on the surface. Just more so.

LOTS OF SYMBOLISM

Allegory involves creating a fairly thoroughgoing pattern of symbolism in which all major events and characters in a story have a meaning beyond themselves and those meanings can be put together to make some sort of overall sense.

This kind of structural symbolism lends itself to social satire, political polemics, fantasy, and religious fiction. There are innumerable examples of each. Some are plotted; some derive their energy from the tension between symbol and reality, the character and what the character stands for, the gradual revelation of larger meanings.

Allegory = Extreme Metaphor

To see how metonymic and metaphoric devices interact in a mixed, that is, both realistic and romantic, fiction, it is perhaps best to begin with the extreme form of the metaphoric or romance pole, the allegory. In an allegory, the only way to approach the characters is by reference to their position in a preexistent code. An analysis of the metonymic context leads nowhere. […] if we were to meet an allegorical character in real life, we would think the person driven by some central obsession. The obsessive-like behaviour of the character is, of course, a result of his or her actions being totally determined by the position he or she holds in the preexistent code. The difference between an allegorical character and a character in a romance is that the romance figure not only acts as if obsessed because of his or her position in the story but also seems obsessed in reference to the similitude of real life created in the work itself.

This combination seems most effectively achieved when a psychologically real character’s obsession is so extreme that he or she projects the obsession on someone or something outside the self and then, ignoring that the source of the obsession is within, acts as if it were without. Thus, although the obsessive action takes place within a similitude of a realistic world, once the character has projected an inner state outward and then has reacted to the projection as if it were outside, this very reaction transforms the character into a parabolic rather than a realistic figure.

The most obvious early examples are those stories by Poe that focus on “the perverse”, that obsessive-like behaviour that compels someone to act in a way that may go against reason, common sense, even the best interests of the survival of the physical self. In many of Poe’s most important stories, the obsession occurs as behaviour that can be manifested only in elliptical or symbolic ways. For example, in “The Tell-tale Heart” the narrator’s desire to kill the old man because of his eye can be understood only when we realize that “eye” must be heard, not seen, as the first-person pronoun “I”.

— Charles E. May, The Art of Brevity