An extended metaphor is a metaphor that's been increased. The extended metaphor here would be:
<span>Be still, sad heart! and cease repining;
Behind the clouds is the sun still shining;
Thy fate is the common fate of all,
Into each life some rain must fall,
Some days must be dark and dreary.
Hope that helps. -UF aka Nadia
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I believe it's "<span>compare and contrast."</span>
