From where I sit, two miles up a mountain on the California coast just south of Big Sur, I have a magnificent view of the ocean, but I can't see the shore. I can observe the undulations and rhythms of the water, its inexorable drive toward a point (in this case, the maps tell me, Ragged Point). I mark subtle and dramatic shifts in its shade and come, by careful attention, to understand what these shifts suggest about temperature, depth, and the nuance of currents. It is an expansive and engaging view, but I miss the shore.

What I am witnessing might find its literary equivalent in the best works of Nabokov or Morrison, the great prose writers' amazing expanses of undulating language, their subtle and dramatic shifts in tone, depth, and motion, their long but inexorable drives toward a point. Much great prose has plenty of poetic qualities to recommend it. One thing it doesn't have is the same thing my view lacks: the predictable moment of physical return, the abrupt interruption, the edge, the beach, the tide break, the line-break, the shore.

When it comes to a shore, the ocean I am watching will do the same thing over and over again. It will break. It will break in relatively the same way several times. Then it will change. It might break that way once or twice more. Or it will change again. Do that a few times, enough times to lull me. Then it will change again. From the shore, if you know what to watch for, you can discover patterns. Surfers track these patterns to predict which wave in a set they will ride. Steve McQueen did this in Papillon and managed, by counting waves until he could predict the most favorable one to jump into, to escape from a prison island.

Poems are not, hopefully, prison islands, but I want to talk about how repetition and variation can work for poems (and readers of poems) when they encounter the anticipated physical moment of return, the line-break, the shore.

Many waves rhyme with each other, meaning they resemble other waves in sound and appearance. One of the things that calms people who visit the shore is this sonic regularity, as well as the swelling of momentum as water gathers force before coming to the locus of return, the tide's break point, the shore. The same goes for a poem. The ear enjoys a good rhyme at the end of a line because we enjoy the rhythmic and sonic regularity those rhymes support. And we enjoy a line that swells and builds momentum as it moves toward its line-break, its moment of physical return.

I could watch the sets all day, excited to see how one break will resemble or differ from the last, how the water will build upon and tumble over itself, how it will look and sound as it rolls over and withdraws back into the main body again. This is what I want to achieve in my poems as well, this degree of motion and momentum. I want the moment of the break to bring pleasure as much from its breaking as from the realization that the break is part of a whole, that each advancing line will bring me great pleasure moving back into the larger body, building momentum, then breaking, then repeating these actions again and again and again.

The best poems deliver what I call the inevitable surprise. We know the line will break, and we might even have an idea of where and how the physical boundary might present itself on the page, and that is part of the beauty, but for that beauty to work to its full potential there must also be much that comes as a surprise.

In the case of an end-rhymed poem, the inevitable might be the fact that we know after a cycle of five iambic feet we must come to an -ay sound. There can be great joy in this anticipation. And if the expectation is thwarted by a poet who presents three iambic feet and an anapest before returning, for a measurable period, to the expected pentameter, then so much the better. Keep us on our toes.

If after a run of end-stopped phrases like "had cream today" and "the girls said hooray" we come to an enjambed line that buries the -ay sound so deeply we nearly forget it, then so much the better. We're always looking for ways to break out of prison.

If we do manage, really, to forget the -ay sound, not for instance to ask, Hey, where's the -ay sound, but to carry on through the poem's interrupted pattern without noticing a break in the pattern, until careful study in a later reading perhaps, then that pattern's break becomes, in its own way, inevitable and it remains also, in its own way, a surprise. Steve McQueen watched the surf break against his prison island over and over until, surprise, he noticed the subtle shift in pattern that always, and inevitably, was there.

Since I think waves can rhyme, it may come as no surprise that I think ideas can rhyme too. I like to end lines this way, following conceptual rhymes, carrying the basic elements of an idea from one line to the next in the same way one might carry a certain element of sound throughout a poem. Just as with sonic rhymes and rhythmic repetition, the execution of rhymed ideas goes a long way toward the pleasure you can garner from a line. As with sonic rhymes, continuity of conceptual rhymes is necessary, but so is variation. A good poem can benefit from the more aggressive wave that follows three delicate ones, the wave that soaks you, that draws even the most timid beachcomber into the water just a little more.

If a poem is broken into lines, you tend to know what's coming: each line will need, in some potentially predictable way, to end. If a poem has good linebreaks, there will still be plenty of opportunity for surprise. That's a huge part of the pleasure of poetry. That's why I love the moment of return, the abrupt interruption, the edge, the beach, the tide break, the line-break, the shore.

Reprinted from A Broken Thing: Poets on the Line, edited by Emily Rosko and Anton Vander Zee, by permission of the University of Iowa Press. Copyright © 2011 by Camille Dungy.