Here is a postmodern metaphor. It's taken from Richard Brautigan's Trout Fishing in America:
It's postmodern, you see, because it's got lots of utterly unnecessary details like the match and the newspaper that don't help to describe the sun. It just keeps scuttling along for its own sake.
This is in sharp contradiction to how metaphors used to be used. Here is Homer describing a chap called Simoisius being stabbed:
...he was cut off untimely by the spear of mighty Ajax, who struck him in the breast by the right nipple as he was coming on among the foremost fighters; the spear went right through his shoulder, and he fell as a poplar that has grown straight and tall in a meadow by some mere, and its top is thick with branches. Then the wheelwright lays his axe to its roots that he may fashion a felloe for the wheel of some goodly chariot, and it lies seasoning by the waterside.
Short was his date! by dreadful Ajax slain,
He falls, and renders all their cares in vain!
So falls a poplar, that in watery ground
Raised high the head, with stately branches crown'd,
(Fell'd by some artist with his shining steel,
To shape the circle of the bending wheel,)
Cut down it lies, tall, smooth, and largely spread,
With all its beauteous honours on its head
There, left a subject to the wind and rain,
And scorch'd by suns, it withers on the plain
And here it is in Chapman's Homer (which Keats first looked into):
Cut off with mighty Ajax' lance ; for, as his spirit put on,
He strook him at his breast's right pap, quite through his shoulder-bone,
And in the dust of earth he fell, that was the fruitful soil
And as a poplar shot aloft, set by a river side,
In moist edge of a mighty fen, his head in curls implied,
But all his body plain and smooth, to which a wheelwright puts
From his innative root, in hope to hew out of his bole
The fell'ffs, or out-parts of a wheel, that compass in the whole,
To serve some goodly chariot; but, being big and sad,
And to be hal'd home through the bogs, the useful hope he had
Sticks there, and there the goodly plant lies with'ring out his grace:
So lay, by Jove-bred Ajax' hand, Anthemion's forward race...
Generally, I prefer Chapman's version; but I think in this passage the Twickenham dwarf wins by a nose.