ABRAMS, M. H. A Glossary of Literary Terms . 7th Ed. Fort Worth: Harcourt Brace College Publishers, 1999.
[p. 5] An allegory is a narrative, whether in prose or verse, in which he agents and actions, and sometimes the setting as well, are contrived by the author to make coherent sense on the “literal”, or primary, level of signification, and at the same time to signify a second, correlated order of signification.
We can distinguish two main types: (1) Historical and political allegory, in which the characters and actions that are signified literally in their turn represent, or “allegorize”, historical personages and events. (2) The allegory of ideas, in which the literal characters represent concepts and the plot allegorizes an abstract doctrine or thesis. (…) John Bunyan’s The Pilgrim’s Progress (1678). (…)
In the second type, the sustained allegory of ideas, the central device is the personification of abstract entities such as virtues, vices, states of mind, modes of life, and types of character. In explicit allegories, such reference is specified by the names given to characters and places. (…)
[p. 6] Allegory is a narrative strategy which may be employed in any literary form or genre. (…) A variety of literary genres may be classified as species of allegory on that they all narrate one coherent set of circumstances which signify a second order of correlated meanings.
BALDICK, Chris. Oxford Dictionary of literary terms. Oxford: Oxford University Press, 2008.
[p. 7] A story of visual image with a second distinct meaning partially hidden behind its literal or visible meaning. The principal technique of allegory is ‘personification’ whereby abstract qualities are given human shape -as in public statues of Liberty or Justice. An allegory may be conceived as a ‘metaphor that is extended into a structured system. In written narrative, allegory involves a continuous parallel between two [or more] levels of meaning in a story, so that its persons and events correspond to their equivalents in a system of ideas or a chain of events external to the tale: each character and episode in John Bunyan’s Pilgrim’s Progress (1678), for example, embodies an idea within a pre-existing Puritan doctrine of salvation.