Years ago, when I was a student in college, a teacher struggled to introduce a classroom full of students to Homer’s Iliad. The bloodshed was all well and good, as was the exotic mythology. But the text itself was laborious, filled with digression and decoration. Why not just say that the two Ajaxes (the Greater Telamonian, and the Lesser, son of Oileus) were inseparable in combat? Why frame their closeness by announcing that

     as two wine-coloured oxen straining
with even force drag the compacted plow 
     through fallow land,

and for both of them at the base of the horns 
     the dense sweat gushes; 

only the width of the polished yoke keeps a 
     space between them
as they toil down the furrow till the share 
     cuts the edge of the ploughland;
so these took their stand in battle, close to 
     each other

They're best buddies. Got it. Why the overkill? Because, as the teacher explained was the case with most epics, Homer was telling a story entrenched by many before him. The cast, the chronology—these were not of his making. The simile became his signature, a way of demonstrating invention despite formulaic source material.

I sat up in my chair. In my own drafts, I was facing the terrible realization that I was not the first scribe of failed love. Tense households? They are a dime a dozen. But with memorable figurative language, I could visit familiar territory and yet leave my mark—a "Kilroy was here" for the page.

At first, this resulted in a veritable kudzu of figuration, as metaphors and similes crept their way across the surfaces of every concrete object or image my poems had to offer. Most poets, including me, refined their approaches with age. Dressing a poem in imagery is like going out for a night on the town: take one piece of jewelry off before you leave the house. Choose wisely.

When writing my first poetry collection, Theories of Falling, I tried to push metaphors as far as possible, extending them into conceits that would (I hoped) provide structure and illumination. In "Cherry Tomatoes," the vehicle of the tomato was a whimsical match to the tenor of warring parents: the one fruit a mother grew in the backyard was the one fruit a father hated. But thinking about a cherry tomato's physicality—the pretty globe that looks impenetrable to the outside eye, resisting puncture up to an utter explosion—helped me better understand the consequences of those repressive yet ultimately aggressive tendencies that can take over a family's domestic dynamic:

          ... The smooth
surface resists, resists,
and erupts in my mouth:
seeds, juice, acid, blood

of a perfect household.

The focus on metaphorical configurations continues throughout the collection. One lover's attention is framed as a burning building. One lover's heart becomes a snail shell. To experience an allergic reaction is to be on a plane as it crashes. People sometimes ask about the simplicity of my titles, for example, "The Green Flash," "The Field," "The Parade," "The Flood," "The Door." It could be that I'm lazy. But I think that to put an ornate title on an effective conceit is no more necessary than to raise an umbrella over the car while driving in the rain.

In discussing metaphor here, I include simile as a complementary force. I often encourage students to sharpen similes into metaphors if the only thing holding them back is authorial confidence. But similes have unique merit and can emphasize a speaker's conscious observation in a useful way. Proof of this is in Sharon Olds’s poem "I Go Back to May 1937," which opens this way:

I see them standing at the formal gates of 
     their colleges,
I see my father strolling out
under the ochre sandstone arch, the 
red tiles glinting like bent
plates of blood behind his head....

The imagery of the red tiles as "plates of blood" foreshadows the family's pain; the use of simile aligns with the repetition of "I see." Olds is trying to impress upon readers the power of witness in this poem, in which the speaker is an anachronistic presence who has traveled back to watch his or her parents as a young couple. The "I" knows the disastrous consequences their relationship will have for the children they raise, so there is an impulse to interfere with their courtship. Yet, as the poem closes,

                                              I want to live. I
          take them up like the male and female
          paper dolls and bang them together
          at the hips like chips of flint as if to
          strike sparks from them, I say
          Do what you are going to do, and I will tell 
               about it.

The future-parents' coupling, whether literal or metaphysical, could be choreographed using the same images without like or as. In an all-too-common editorial mode in which concision reigns as king, one might naively coach the poet to trim out the "I" and observe forcefully that the parents are paper dolls, are flint. "Tighten," we might say, which has become the "more cowbell" of the contemporary MFA workshop.

That would be a tactical error. On a technical level, the result would be a mixed metaphor asserting that the male and female bodies are simultaneously as flexible as paper and as hard as stone. More important, that version of the ending would value the scene of the parents over the poem's true center, the observer's evolving attitude toward them. The poem is about makership, so the use of simile is not only apropos but also critical. Readers need to experience the thought process of the observer, following along from using like and as, fumbling toward resolution, culminating in the certainty of the imperative "Do what you are going to do." Though the closing phrase is uttered in future tense, it is clear the telling has already begun.

That is strategic use of simile at its best. But I'd be remiss if I did not admit that for many poets, the choice between simile and metaphor may be decided by whether like or as better completes the rhythm of a line. 

The most compelling examples of metaphor or simile are ones in which the relationship between the tenor (inspiring subject) and the vehicle (figurative object) provides a click of recognition. Poets see how one fits the other, even if they have never articulated it before. Yet on second look, the figurative language adds revelation. 

That's a fancy way of declaring that it's not enough to pull a verbal backflip. You've also got to stick your landing.

In "Night Madness Poem," Sandra Cisneros claims

In dreams the origami of the brain
opens like a fist, a pomegranate,
an expensive geometry.

Not true.
I haven't a clue
why I'm rumpled tonight.

Though the contrarian speaker is quick to disown her own metaphor, the phrasing of a brain in terms of origami satisfies in the congruence of image—the gyri and sulci of the brain's surface are re-expressed as the ridges and tuck-folds of, say, a Japanese water bomb, one of my favorite origami forms as a child. As a reader, I experience that initial affirming click of perception.

Furthermore, I revisit the metaphor and appreciate how it transposes the tension between nature and nurture to the physical push/pull between paper (variant in its cloth) and hands (variant in their dexterity). I am encouraged to think about origami's tradition of preparatory creasing, the valley fold, in order to make a form take hold. What could this reveal about the mind's predisposition of pathways? 

Just as Homer jolted his audience from its bloodlust by detouring through pastoral farm fields, so figurative language can complicate a clichéd premise. Sylvia Plath’s "Nick and the Candlestick" poem opens with a mother carrying a candle into the nursery to check on her newborn son. The closing lines are "You are the one / Solid the spaces lean on, envious. / You are the baby in the barn." This sounds like something Thomas Kinkade could illustrate. But the poem's opening challenges any expectation for an affectionate ode:

I am a miner. The light burns blue.
Waxy stalactites
Drip and thicken, tears

The earthen womb
Exudes from its dead boredom.

Well then. This may be a poem of motherhood, but it is unmistakably Plath's version of motherhood. "Sylvia was here."

Some poems explicitly acknowledge perception's transformative force. In Nick Flynn’s "Sudden," the speaker grapples with his mother's suicide by fixating on the wording of the public report: "If it had been a heart attack, the newspaper / might have used the word massive, / as if a mountain range had opened / inside her ... If it had been // terminal, we could have cradled her as she grew smaller[.]" Though it's illogical to grant determinative power to an adjective chosen after the fact, for a moment readers are carried up into the mountains with Flynn's proposed simile, transported to the vista of the alternative realities in which the mother's death is an unstoppable act of nature or an opportunity for caregiving and conscious good-byes. But soon, readers learn the actual word used was suddenly, and "the world became a bell we'd crawl inside / & the ringing all we'd eat."

The job of the poet is to take a scenario, persona, landscape, philosophical concept, or relationship dynamic and render it in terms both sublime and clarified. No tool is more critical to this task than figurative language. Often, praising intensity of voice is recognizing a ruthless capacity for metaphoric invention. This is true of so many of my favorite poets: Cisneros, Plath, Flynn, Li-Young Lee, Emily Dickinson, and Langston Hughes.

Several stories explain how "Kilroy was here" became endemic graffiti (in the United States, anyway; Australians have "Foo was here"). A 1946 article in the New York Times identifies Kilroy as James J. Kilroy, a shipyard inspector born in 1902. Supposedly Kilroy marked vessels as they were being built, in sealed hull spaces inaccessible to the public. Upon encountering a work-in-progress, he would chalk the individual rivet where a shift had ended.

This is a perfect metaphor for writing poetry because poets are not trying to say that they were merely here. Poets are not visitors. Not tourists. Poets are Kilroys, deep in the vessel, where not just anyone can venture, working toward understanding from the inside out. Making sure the ship is seaworthy, one rivet at a time.

This essay originally appeared in the Spring 2012 issue of American Poetsthe biannual journal of the Academy of American Poets. Copyright © 2012 by the Academy of American Poets. To receive American Poets, become a member online.