"A mind's reach should exceed its grasp, or what's a meta phor?"
—unknown, riffing on Browning
Metaphors and similes equate or compare one thing with another. They can be used to describe the unfamiliar in terms of the familiar, or to shed new light on the familiar by comparing it to something unexpected. And sometimes they can simply provide interesting or entertaining juxtapositions.
Some writers, notably some of the pulp and noir writers of the 1930s through '50s, weren't afraid to hurl themselves into a metaphor like trapeze artists, grasping at empty air until, at the final moment, just before credibility stretched to the breaking point, they closed their hands around a solid bar and found they'd successfully crossed another blind leap of faith. Just watch Raymond Chandler in a moment of acrobatic poetry: "Under the thinning fog the surf curled and creamed, almost without sound, like a thought trying to form itself on the edge of consciousness." (From chapter 23 of The Big Sleep.)
Leigh Brackett began writing sf in the 1940s, and co-wrote several well-known screenplays, including The Big Sleep (with William Faulkner!), Rio Bravo, and The Empire Strikes Back. Here are a couple of luscious tidbits of metaphor from her later work, specifically The Ginger Star, the first book of a science-fantasy trilogy featuring her adventurer hero Eric John Stark:
"Skaith's old ginger-colored sun was going down in a senile fury of crimson and molten brass, laying streaks of unhealthy brilliance across the water." (p. 5)
"A crowd gathered, clotting round Mordach's party like swarming bees." (p. 41)
Back to Chandler: "The eighty-five cent dinner tasted like a discarded mail bag and was served to me by a waiter who looked as if he would slug me for a quarter, cut my throat for six bits, and bury me at sea in a barrel of concrete for a dollar and a half, plus sales tax."
Moving right along, here's Edith Wharton, from The Age of Innocence: "The immense accretion of flesh which had descended on her in middle life like a flood of lava on a doomed city..." (p. 18, discussing Mrs. Manson Mingott, aka Catherine the Great)
The best metaphors I've encountered recently hail from West With the Night, the autobiography of Beryl Markham, an airplane pilot in Africa in the '30s who gained some renown for being the first person to cross the Atlantic solo in an airplane flying from East to West. If there were any justice, she would have gained much more renown for her writing, about which this guy you may've heard of (name of Ernest Hemingway) wrote: "[She] can write rings around all of us who consider ourselves as writers." Here are some examples:
"Everything those [textbook] authors said was sound and sane and reasonable, but they went on the theory that truth is rarer than radium and that if it became easily available, the market for it would be glutted, holders of stock in it would become destitute, and gems of eternal verity would be given away as premiums." (p. 190)
"[The two rivers] enclose the Ukamba like a frayed noose dropped to earth by an intrigued Satan, to mark a theatre for later labours." (p. 201)
"Nature ... developed [elephants'] bodies in one direction and their brains in another, while human beings, on the other hand, drew from Mr. Darwin's lottery of evolution both the winning ticket and the stub to match it." (p. 205)
"[A] man ... so angular as to give the impression of being constructed entirely of barrel staves." (p. 209)
Those writers of a few decades back weren't the only ones who could go three rounds mano a mano (or womano a womano) with a metaphor. Modern examples of extremism in metaphor, however, tend rather more toward the ridiculous than the sublime. The New Yorker used to run hilarious examples of unfortunate or overextended metaphors under the heading "Block that metaphor! " Here are a couple that perhaps ought to have been blocked:
"A shoemaker could imagine that he was sewing the leather of passion with the thread of freedom to produce shoes of enlightenment." (Quoted by Otavia Propper, from an unknown book.)
"The FAA is far from out of the woods, and the flip side of its shiny Krugerrand of reassurance is a dull and gritty kopeck of uncertainty and unanswered questions." (From a Time article about Y2K and the FAA, written by Nick Oredson.)
In a science fiction story by Dmitri V. Gat that I read a while back, a red-haired female character entered a room "dressed in a fashionable hemi-nude culotte which bared the left side of her body." I still can't decide whether I'm amused or appalled by the sentence that followed: "Her breast peeked from behind a spray of red hair like a pink-nosed rodent from a grassy nest."
Metaphors carried to (and sometimes beyond) their logical conclusions can obviously be entertaining. They can be made even more entertaining by derailing them with what's commonly known as a mixed metaphor. In a letter to a friend, for instance, I once bemusedly watched myself write, "she steeled her threadbare nerves." Some mixed metaphors become standard parts of the common discourse; for instance, skipping lightly over the (air)waves of television channels became known as channel-surfing, so it was only logical that skipping lightly across the surface of the World Wide Web should be termed Websurfing, although the notion of surfing across something as sticky as a web would be a bit hard to swallow if anyone had stopped to think about it. It only gets worse when you consider the image of surfing along the "information superhighway"...
Yes, I know mano a mano means "hand to hand."