Allegory

From Srafopedia

An allegory (from Greek αλλος, allos, "other", and αγορευειν, agoreuein, "to speak in public") is a figurative mode of representation conveying a meaning other than (and in addition to) the literal.

Allegory is generally treated as a figure of rhetoric, but an allegory does not have to be expressed in language: it may be addressed to the eye, and is often found in realistic painting, sculpture or some other form of mimetic, or representative art.

The etymological meaning of the word is broader than the common use of the word. Though it is similar to other rhetorical comparisons, an allegory is sustained longer and more fully in its details than a metaphor, and appeals to imagination, while an analogy appeals to reason or logic. The fable or parable is a short allegory with one definite moral.

Much of His Dark Materials is allegorical, as, according to most, is even more of the Chronicles of Narnia.

Source: Wikipedia: Allegory