What is an extended metaphor?

An extended metaphor is a literary device that makes a comparison between two generally unlike things or ideas in a passage that continues for more than one sentence or paragraph.

Traditional metaphors typically only last for the duration of a phrase or sentence, while extended metaphors continue on to make a larger comparison. Authors use them to establish more powerful examples as well as to create stronger impressions in readers' minds. A literary example of extended metaphor in action is found in Emily Dickinson's poem "Hope is the thing with feathers," in which she compares hope with a feathered creature to make her point.