Right in the opening line to Consider the Lobster, David Foster Wallace packs his whole argument into a single metaphor.
By conflating the lobster industry with a nervous system, DFW makes the case upon which the rest of the essay expands: that we ignore animal suffering for the sake of social convention.
Masterful use of a literary technique in nonfiction, going beyond mere description to packaging the essay's entire thesis into a single image.
That's the important thing about metaphor: it's not enough to simply link one thing to another thing; it's important that the second thing modifies or enhances our understanding of the first thing, so that the reader's voyage from things 1 to 2 is worth it.