a. While a metaphor is limited in length, an extended metaphor is developed over the course of a poem.
In general, a metaphor is a figure of speech that asserts that one element (person, animal, thing, quality, event, etc.) is similar to another element that in reality, or literally speaking, are not related in any way. While a metaphor is limited in length, an extended metaphor is developed over the course of a poem or throughout a series of sentences in a paragraph
For example, “A dream itself is but a shadow” is a metaphor, its length is limited. And one example of a extended metaphor can be understood with the following poem “Hope is the Thing with Feathers” by Emily Dickinson:
Hope is the thing with feathers
That perches in the soul,
And sings the tune – without words,
And never stops at all,
And the sweetest in the gale is heard;
And sore must be the store
That could abash the little bird
That kept so many warm.
I’ve heard it in the chilliest land,
And on the strangest sea;
Yet, never, in extremity,
It asked a crumb of me.