It's early morning. I'm sitting in a corner window on the thirty-fifth floor of a hotel in San Francisco. Outside, nothing but fog, saving me from my own strong fear of heights. Where yesterday I could look out on city streets, moving lights, water in the distance, today there is nothing. No little cat feet, but a dense gray wall of impenetrability. Though if I should go down in the elevator and walk out the door, I could move through it easily enough.

Suddenly, a whir in front of me, and a wire mesh cage holding two men appears from above. They move past and disappear; I only know they are there because the ropes outside my window sway back and forth, revealing the tension of the cage in its circumscribed movement below me, thirty some floors above street level. Looking through the window on my right, I see two more men in a similar cage, though theirs is narrower, surrounded by what looks all too much like flimsy green canvas. They wear hard hats—one yellow, one white—and are tethered to their narrow walkway by yellow fabric straps. For fifteen minutes, with black tape and a razor, they work on one section of a ledge. Holding the building together with black duct tape, or so it appears, though now they are rubbing and rubbing. Out of the fog, the sudden appearance of the technicians who hold the structure together.

When I look out again, one of the men is gone, the one with the white hat. Where did he go? And how? He's thirty-three stories up, and the windows don't open, do they?

Sometimes the world hands you metaphor. For the past hour, I've felt a bit unsettled, the way I feel when reading Robert Hayden's “Those Winter Sundays”—the mystery that still resides in the phrase “fearing the chronic angers of that house.” I've also felt astonished, the kind of astonishment that quickens every time I hear “In the room the women come and go / Talking of Michelangelo” and think, Where did that come from? And I've been unexpectedly delighted, as in “Time held me green and dying / Though I sang in my chains like the sea.” At my window I have, I now realize, experienced the underlying tensions of a poem.

What has happened to tension? That tug of war between the line and what the line can contain? The standoff between form and content? The tectonic slippage between what is stated and what is implied?

Tension is not simply a matter of craft, but of something internal—the poet's willingness to launch him- or herself into unknown territory. All too often, I open a book to find what I have come to call the “standard poem of self-expression”—slack lines of reportorial poetry in which the poet recounts circumstances with the assumption that, because he or she is thinking “correctly,” the reader will, by definition, agree with what is being said. And I may. But I do not read only for confirmation of my own ideas. So the sameness—if not of content, then of technique and, worse, stance—worries me. What is the future of an art whose practitioners won't take genuine risks, including the risks of self-discovery, and who congratulate themselves for speaking what amount to no more than preconceived or prepackaged “truths”?

Randall Jarrell worried about something similar—but he was concerned about the critics: “May one of them say to the others, soon: ‘Brothers, do we want to sound like the Publications of the Modern Language Association, only worse? If we don't set things straight for ourselves, others will set them straight for us—or worse still, others won't, and things will go on as they are going on until one day even you and I won't be able to read each other, for sheer boredom.’” Now poets seem to have left themselves vulnerable to the same charges. Sometimes I suspect my own abilities to keep an open mind, but mostly I've come to realize that my boredom is at stake—and that contemporary poetic practices have done little to alleviate it. In a profound way, boredom is the ultimate test in art: if the work stops being genuinely interesting, it doesn't matter. Art that disturbs us is always more interesting than art that proclaims, or just solicits approval. I like the risk-takers. The poems that hold my interest are the ones that exhibit some form of tension.

The one remaining man (the one with the yellow hat) pushes a button and one side of his walkway drops a few inches. He's standing on a sloping board! I'm terrified by the very thought of it. And then a hand—only a hand, seemingly disembodied—appears through the railing above him, handing him something—more tape? some putty?—but whose hand is it, and how did it get there?

When Robert Frost wrote in his Notebook “for my pleasure I had as soon write free verse as play tennis with the net down,” it was necessary to think about what he conceived of as his “net.” Surely it was not merely the empty husk of traditional forms—the sonnet without substance—but a second net of his own devising. Jeffrey Meyers, a recent Frost biographer, has stated that “he maintained that his verse sprang from the strain or tension that evolves when a strong rhythmic pattern, based upon strict or loose iambic meter, is played against the irregular variations of common speech.” So Frost built his own net, a warp of form through which to weave the weft of colloquial speech, the “sentence sound” that gave his poems their particular flavor. Note the surprising force in the ten one-syllable words that open the blank verse of “Directive”: “Back out of all this now too much for us.”

The concept of warp and weft is a useful one—although it's often impossible to tell one from the other in the finished fabric. Still, we do know that the warp provides a structure across which the weft has been woven. Form, of course, supplies one external frame, but often the warp is internal. The poet may choose any of a number of aspects of craft—patterns of speech, patterns of sound, an appeal to the visual, extended metaphor, image, tone, narrative, lyric intensity—and then put them together in any of a number of combinations. That is, one poet may seem to work sound against a structure of “given” metaphor while another may do the opposite, working metaphor against a pattern of sound. The problem is to tell warp from weft, and possibly it can't be done in any ultimate sense. Yet it's an interesting way to think about poems, and it may be that readers intuitively understand when a poet is working in more than one direction. The result—the individual poet's unique blend—can be seen as one source of tension in a poem.

In the 1960's, when both Robert Lowell and Sylvia Plath shifted from formal structures toward free verse, the result was an emphasis on content. But it was content enhanced by the way their lines became more compressed, their imagery more raw and urgent. Interestingly, their poems remain compelling when so many modern-day “reruns” do not, so it cannot be merely the confessional mode (now all too familiar) nor the content itself (the ante of victimization has been raised in several successive rounds) that makes their poems survive the test of time. I suspect that, for both Lowell and Plath, the poem was a quest, a necessity, rather than a statement.

Personal experience makes a natural warp, but over the years I've realized that, without some other element of craft, content is what is ultimately boring. Content-driven poems are good for the first reading, but they often have little to fall back on—and any retold story usually does begin to fray. The poems that remain as surprising the twentieth time as the first (and perhaps more surprising for some newly perceived nuance) have elements that hold our interest over and above content, and in the face of shifting attitudes. Pablo Neruda infuses his work with the magic of metaphor, welding the abstract to the concrete. William Carlos Williams and Marianne Moore intrigue the eye, while Wallace Stevens and Theodore Roethke pique the ear. In this way, they create intricate spaces for new and ever more intricate readings.

And now the hand is hitching a strap to the railing and the second man (the white hat) is climbing back over it into the cage. The scene looks exactly as it did before. If I'd looked away, I might never have known what had gone on, how they went about their business in and out of the cage. And in front of me, still the fog, still the ropes that sway with the weight of what they are holding, out of sight below me. And beyond them, the city I cannot see, but know is there. …

Paul Muldoon is America's master of form. (That's right, he has become a citizen, though Ireland may not gladly give him up.) He is so adept, has so much dexterity, that in fact form doesn't serve as much of a “net”—he seems to need to generate increasingly elaborate superstructures (forms within forms), almost as though in building them up he can create the effect of tearing them down. For Muldoon, it's ideas that matter. He is so referentially brilliant that idea and form together can strike spectacular sparks—but only sparks. Muldoon needs to engage emotional as well as intellectual material in order to create the great poems of which he is capable. In his previous book, The Annals of Chile (1994), he gave us one of the most important poems of the last half of this century in “Incantata” and a significant long poem in “Yarrow.” I find it hard not to read his new book, Hay, in the afterglow of this accomplishment.

But what is a poet to do when he or she has written something of genuine importance? Wait years for the next great poem? Or follow William Stafford's advice to “lower your standards and go on”? Muldoon seems to have opted for keeping his engines idling, demonstrating once again his ready wit and facility with words as he explores just about every aspect of living. “Sleeve Notes” is a commentary on twenty-one pop musicians or groups from Jimi Hendrix to Dire Straits; a sequence of one hundred haiku chronicles the changing seasons in New Jersey. Some of the latter work beautifully in the traditional sense:

Beyond the corn stooks
the maples' firewood detail.
Their little red books.

Others have the feel of mere reportage:

I've upset the pail
in which my daughter had kept
her five—“No, six”—snails.

Rhymed haiku, perfect syllable counts, but to what end? The enterprise does not quite live up to its promise, reveals nothing new about the old form, marks time but does not remake it.

In Hay, Muldoon reveals his linguistic agility, his erudition, his knowledge of pop culture, his cunning wit, his playful perceptions, and his ability to toss them all into one grab bag and pull them back out in innovative poetic exercises. What this collection hints at, gives us glimpses of but does not truly provide, is poetry—the kind that takes off the top of your head. The poems of Hay are mental puzzle-making, material looking for significance, causing me to suspect that this book was published too soon after the last one, that his publishers have done him no favor exhibiting his facility without demanding more depth. Even poems with the immediacy of personal content, like “Longbones,” end up feeling a bit contrived, orchestrated to fit their rhymes rather than allowing form to reveal inner urgencies. The long finale, “The Bangle (Slight Return)” is so playful—it takes its cue from Oscar Wilde, adds Australian geography and slang, incorporates an earlier play on “errata” to undercut its own vocabulary—that, while it is decidedly a tour de force, one wonders what force it is touring.

Oddly, the book's two concrete poems are among its most moving. “The Plot” simply spells out “alfalfa” over and over until the empty space in the middle of the poem asserts its “alpha” between two “alfas,” and something begins to sprout. “A Half Door Near Cluny” takes “stable” and makes the reader see stables, table, tables, able, lest, stab, blest, until the brain cannot but add blessed, establish—house and stable meshed with what the door reveals, conceals. With stark simplicity, Muldoon has shown us how a word can contain multitudes.

Three poems in Hay demonstrate the tensile strength of Muldoon's best work, easily walking the tightrope of craft while below him content swirls and boils. “Wire,” a sestina in which the repeated words become increasingly ominous, superimposes memories of war-torn Ireland on an innocent walk in the Connecticut countryside until the speaker imaginatively enters the territory of the terrorist, all innocence transformed by the distorting lens of suspicion: “the endless rerun / of Smithfield, La Mon, Enniskillen, of bodies cut // to ribbons as I heard the truck engine cut / and, you might have read as much between the lines, / ducked down here myself behind the hide. As if I myself were on the run.”

“Third Epistle to Timothy” also contains an imaginative entry into the life of another, as Muldoon reconstructs his father's days as an eleven-year-old servant to the Hardys of Carnteel. The boy is subjected to hard physical labor and the fire and brimstone of his boss's religious fervor, coupled with the fervent history of the Irish cause. The tenth and final section fuses that experience with those of literature, ending with as dark a vision of the future as of the past:

That next haycock already summoning itself from windrow after
                                                                                                              wind-weary windrow
while yet another brings itself to mind in the acrid stink
of turpentine. There the image of Lizzie,
Hardy's last servant girl, reaches out from her dais
of salt hay, stretches out an unsunburned arm
half in bestowal, half beseechingly, then turns away to appeal
to all that spirit troop
of hay treaders as far as the eye can see, the coil on coil
of hay from which, in the taper's mild uproar,
they float out across the dark face of the earth, an earth without form, and void.

In a substantive and quite astonishing feat, “They That Wash on Thursday” rhymes each of its fifty lines on the word “hand”—fifty lines in which Muldoon moves from the initial gamelike quality of his rhyming to a hard look at the hard life of the speaker's mother and the hands of the women he has loved, from wry self-mockery toward a serious conclusion where Ireland and America coexist in his daughter's freehand drawing of “a green field on a white hand.”

I believe that Paul Muldoon will be seen as one of America's finest poets (as he is already considered one of Ireland's); added to his previous accomplishments, the range and substance of these three poems confirms this prediction. For Muldoon, content is the tension because he always plays his tennis with more than one net.

And now there is a third figure—a dark-haired young man without a hat, wearing blue straps—in the cage. The two others are lowering the cage and he is leaning out, examining the corner of the building, testing the windows for tightness. The two stand by with their razors and tape. Now the one without a hat is talking on a telephone. He cups his hand around his ear, as though to hold sound at bay. I, of course, can hear nothing.