What is a metaphor that is extended throughout an entire work, often elaborated on in detail?

An extended metaphor is a comparison between two unlike things that persists throughout a narrative or a work, often developing more intricate layers of meaning as the piece progresses. This figurative language not only highlights specific characteristics of the two subjects being compared but also allows the author to weave a thematic thread that connects various elements of the work. By elaborating on this metaphor in detail, the author deepens the reader's understanding and engagement with the text, making it resonate on multiple levels.

In contrast, a simile is a brief comparison that uses "like" or "as," making it less comprehensive than an extended metaphor. Allegory serves as a narrative technique where characters and events represent broader themes and ideas, but it does not necessarily hinge on a singular metaphorical comparison throughout. Personification attributes human traits to non-human entities, which can create vivid imagery but does not encompass the extended conceptual frameworks characteristic of an extended metaphor.