Allegory

A figure of speech, which has been defined by Bishop Marsh, in accordance with its etymology as, "a representation of one thing which is intended to excite the representation of another thing." ("A figurative representation containing a meaning other than and in addition to the literal." "A fable or parable; is a short allegory with one definite moral."--Encyc. Brit.) In every allegory there is a twofold sense--the immediate or historic, which is understood from the words, and the ultimate, which is concerned with the things signified by the words. The allegorical interpretation is not of the words, but of the thing signified by them, and not only may, but actually does, coexist with the literal interpretation in every allegory, whether the narrative in which it is conveyed be of things possible or real. An illustration of this may be seen in (Galatians 4:24) where the apostle gives an allegorical interpretation to the historical narrative of Hagar and Sarah, not treating that narrative as an allegory in itself; as our Authorized Version would lead us to suppose, but drawing from it a deeper sense than is conveyed by the immediate representation, and you can find more about that here on st-takla.org on other commentaries and dictionary entries.(Addison's Vision of Mirza and Bunyan's Pilgrim's Progress are among the best allegories in all literature.)