Pearl, miniature from Cotton Nero A.x. The Dreamer stands on the other side of the stream from the Pearl-maiden. Pearl is one of the greatest allegories from the High Middle Ages
As a literary device, an allegory is a metaphor in which a character, place or event is used to deliver a broader message about real-world issues and occurrences. Allegory (in the sense of the practice and use of allegorical devices and works) has occurred widely throughout history in all forms of art, largely because it can readily illustrate or convey complex ideas and concepts in ways that are comprehensible or striking to its viewers, readers, or listeners.
Writers or speakers typically use allegories as literary devices or as rhetorical devices that convey (semi-)hidden or complex meanings through symbolic figures, actions, imagery, or events, which together create the moral, spiritual, or political meaning the author wishes to convey.
First attested in English in 1382, the word allegory comes from Latinallegoria, the latinisation of the Greek ἀλληγορία (allegoría), "veiled language, figurative," which in turn comes from both ἄλλος (allos), "another, different" and ἀγορεύω (agoreuo), "to harangue, to speak in the assembly" which originate from ἀγορά (agora), "assembly".