As a child, you followed the rules — that was your job. It was wrong to hit your little sister, to giggle or tickle or otherwise revel in pleasure, to take — or even want — the biggest piece. It was right to let your friends go first, to think of other people before yourself, to sit up straight and use the proper fork. It was downright dangerous to disagree.

That was fifty years ago. Marriage and motherhood have intervened, but you still try to do what’s expected, and anything that makes you stand out is a test. Like right now: you are somewhat uncomfortable as you drive your grown son Allen to Chicago’s Field Museum for an outdoor performance of music and sonic sculpture. You know it’s the right thing to do. In fact, Allen might enjoy the performance more than any other person on earth. It will have everything he loves: strong rhythms, deep vibrations, large scale, mass movement. Nonetheless, small ripples of apprehension spread outward from a knot in your stomach. Allen talks as you drive from his group home to the lakefront museum: “He like music. Rock-and-roll, too. He like music, yeah.”

The wind off the lake has cleansed the city air, and the sun has soaked it with warmth and brilliance. You park and make your way toward the museum, wishing Allen would get the hang of walking next to you, instead of either right in front or far behind. You hate stepping on his heels, and you shrink at the thought of how you must look standing and waiting for him, calling his name and telling him to walk faster. He pauses to scratch the sidewalk with his fingertips, tries to lick each lamppost you pass.

“We’re going to hear music,” you tell him.

“Good music,” he says. “I like church. I got a fourteen. Neighborhood.”

Years of experience have taught you to decipher some of his non sequiturs. Church goes with music. Neighborhood is a shortening of your habitual response to his request for a stop at Burger King: “We don’t have one in our neighborhood.“ Fourteen is a mystery.

“I’m fat,” Allen continues. “Daddy’s dead.”

You are no longer surprised or hurt by the abruptness of this last statement. “Yes, Daddy’s dead,” you say, and you immerse yourself in the museum’s splendid stone facade rising in front of you: the intricate jumble of red and gray skyscrapers on your left, like a cubist painting; the bright, open expanse of lake and sky on your right. You take the city in, let it fill you up.

You have to enjoy the world on your own now. When your husband was alive, the two of you shared every sight and sound and taste, transformed them into dialogue. You filled each other up, cast a single shadow. You were more comfortable standing out when you could do it with him. You learned not to care what other people thought. But the ragged edge your husband left when he died bled you dry. For years, you lived in a dark world: the air itself was cruel, and the space of your bedroom seemed vast and empty.

That was a decade ago. Now the youngest of your four children has just gone off to college, and Allen has been happily settled among his peers at the group home for the last five years. Sure, you miss the things you’ve lost: the house being alive with talk and music, the late-night suppers in bed, the satisfaction of cooking for someone else. You are inescapably single. Sometimes you would like to say, “Look!” But solitary pleasures have begun to percolate through the pain. You cook and eat and drink alone, uncensored. You take the biggest piece (and sometimes still wonder if it is right). Your appetite, previously unseen, has become a way of life. The city intoxicates you. It sings with little joys: the profusion of produce at the farmers’ market; the lapping water of the lake. You float through it, blending into the colorful background.

But you can forget blending in today; today is for Allen. Everyone can see you as you circle the museum, your son still lagging behind. A huge black-metal dinosaur skeleton rises starkly in front of you, glinting with tiny points of sunlight, and you hear the seductive call of drums. Allen starts to bolt toward the music, and you put a hand on his shoulder to slow him down. You don’t have to hang on to him, your husband’s voice says in your head. He liked to remind you that children are bound to their parents at least as tightly as parents are to their children: let them go, and they’ll cling to your side.

As you approach the terraced sculpture garden, where people sit on the grass or on stone railings among the musicians, you conceal your desire to hide, trying to appear normal, even friendly. You sink gratefully into the anonymous sea of people, yet remain alert to the possibility of seeing someone you know, ready to jump like a sociable fish if necessary.

Here comes someone: Allen’s older brother Seth. He has zoomed down the lakefront on his in-line skates to meet you. Allen examines Seth’s black wrist guards, and Seth undoes the Velcro straps and fastens the wrist guards around his brother’s arms. Delighted, Allen pretends to skate, following Seth around the garden. Allen calls the wrist guards “muscles.” “See my muscles?” he says, gliding from foot to foot. While Allen and Seth befriend a couple sitting on the grass with a dog, you seek out the museum’s concessions to buy some snacks and drinks. When you return, Allen is still playing with the dog and wearing the wrist guards.

The performance begins. A man sits down on a chair placed on a picnic table and proceeds to bow an amplified cello. Deep, multilayered sounds flood out of the instrument, which is soon joined by the beat of drums. Hundred foot strings are stretched from a wooden frame on the ground to another mounting on the roof of the museum. Musicians with gloved hands reach up to stroke these strings with strong pulls, using their whole bodies, setting off low vibrations you can feel in your gut.

You look over to see how Allen is reacting. The excitement will probably agitate him, making him growl and bite the back of his hand, leaving red welts. Maybe it will be all right at an outdoor performance, where extraneous noises are less noticeable. Allen’s eyes jump around, and his hands jerk, but so far he remains quietly engrossed. You want to give yourself over to the music, to let its deep vibrations shake you to your roots and its melodies float you to the treetops, but your eyes keep shifting toward Allen, checking to be sure that he is not about to stand up, dart off, or shout. He’s OK. Don’t worry about him, says your husband.

A dancer undoes her huge red-silk skirt and trails it behind her like a cape, running between the musicians. A man spins something that looks like a top and makes tiny, squeaky sounds when he touches it with a stick. Another man in bluejeans runs in a big circle, blowing on a conch shell. When the music pauses, the running man stops and tells the audience about the enormous ground-to-rooftop stringed instrument, a sonic sculpture called the Earth Harp.

You walk with Allen around the terraces, making sure he sees each musician. Two dancer-drummers play complex percussion instruments, each with two drumheads, one horizontal at waist level, and the other vertical at eye level. The musicians play both heads at once, spinning and jumping between beats.

When the show is over, Seth starts to head for home on his skates. He decides to let Allen keep the wrist guards.

“Just until he goes back,” you say.

“No, he can keep them,” says Seth. “I’ll get some more.”

People are lining up to put on cotton gloves and try out the Earth Harp. Allen will not ask to play; he doesn’t even know that he can. You should encourage him. You should take him and get in line in that revealing sunlight and show him how to put on the cotton glove and stroke the strings. Maybe he will try it; maybe he won’t. What are you so worried about? asks your husband.

But you know Allen will hold everybody up. He will say, “Glove?” and laugh and bite his hands, afraid to try. People will wait politely, indulging him and you, and you will shrink, aware that you are taking two or three times as long as anyone else. If someone in line coughs, you will be sure people are losing their patience. You will put on a glove yourself and show Allen how, sliding your hand on the overhead string and startling him with the sound. You will look only at him and the string, avoiding the spectators’ eyes, imagining that no one can see you. You often think this way, you realize, like a child playing peekaboo. You are always embarrassed to waste people’s valuable time, and when someone speaks to you, your eyes keep shifting as though you had a bus to catch.

You stand undecided. People look at you and Allen, then away. You feel yourself — your head, your shoulders, your hips — standing out against the background of stone.

“Liptauer?” Allen says loudly, and everyone looks “Liptauer today?”

Allen is referring to the cheese spread made with paprika that his father loved. Alone of all your children, he remembers and asks for it. He likes to help you buy the cream cheese, blue cheese, and green onion, and he adds the spices himself: a drop of Worcestershire, a dollop of mustard, and lots of paprika — hot and sweet.

If your husband were standing next to you, he wouldn’t dream of leaving without Allen’s playing the Earth Harp. He wouldn’t care what other people thought. Seth has his father’s broad gestures, his color and daring. But Seth has gone home.

In part, you married your husband for his freedom and nerve, for the way he’d suddenly stop on the street, take a deep breath, and raise his arms to embrace the world, as if he deserved its gifts. You weren’t as happy when he barged into restaurants without waiting to be seated, but you and he balanced each other. The two of you worked together to raise Allen. Your husband taught him to light the candles on a birthday cake, and you taught him how to blow them out. You taught Allen about red and green lights, and your husband taught him to find his way to the grocery store. You bathed and dressed Allen, and your husband took him for walks, encouraging him to greet strangers on the street. (Allen still does this, extending his hand and saying, “How you?“ to each person he passes.) If Allen persuaded a stranger to buy him some candy, your husband was happy.

When Allen was a newborn, you both called him “Zen Baby,” for his peaceful nature. Later, you shared a gnawing suspicion of his floppiness, his failure to sit up on schedule. Your husband defended Allen against the experts’ tests, hanging on to his conviction that Allen was special, perhaps even holy.

Nixon’s Watergate coverup was just being exposed when you first put a name to Allen’s condition: “retarded.” No one wanted to say the word to you. “Developmentally delayed,” said the social worker. Allen was three and couldn’t walk. A name couldn’t make it any worse than it already was, you thought. You wanted to say the word before someone said it to you. More than anything, you hoped Allen would never hear it, would never know this harsh fact about himself. “Retarded, retarded,” you repeated to yourself. A “retard” was a discard, but retarded was all right, you thought, just a fact about a person.

You listened to the news about Watergate on the radio in the starkly lit kitchen while Allen played on the floor, lying on his stomach and propping himself up on his hands. You began to use the unacceptable word with your husband. He shared your embattled joy that Allen would never be able to accomplish any serious evil.

“Liptauer today, right?” repeats Allen. “Not tomorrow. Not tomorrow, I know.”

You could leave now and go make Liptauer with Allen. You see yourself balancing on a seesaw with your husband: he jumps off, and you crash down, tumbling over backward until you come to rest in a place you never intended. He would not be pleased if he could see you now. You realize for the thousandth time how much you needed his counterweight. But this is your decision, and you will have to make it on your own. How easy it would be to turn and vanish, to duck out. No one would know. Seth’s gone; Allen can’t tell anyone. Coward, you say to yourself. But if you stay, you’ll be pricked by a hundred arrow-like eyes, with no place to hide. Your eyes skim stone, water, sky.

“Would he like to play the harp?” asks a woman with long earrings and red hair. “Go ahead,” she says, and before you realize what’s happening, she ushers you in front of her — too late now to fade back into your concealing world.

“Liptauer later,” you say firmly to Allen as you put an arm around his shoulder and guide him. Just ahead of you, an elderly woman straightens her bent frame and reaches up as high as she can to squeeze one brief note out of the string. Allen’s head wobbles from side to side, and his hands jerk with excitement. “I’m ’tellgent,” he says. People are nodding encouragement. You hand Allen the glove. “Put it on,” you tell him. “Now reach up.”

“Like this?” he asks.

“Go ahead and touch it,” you say. He is reaching, but not high enough. “A little bit more,” you say, trying not to sound impatient. “You can do it.”

Allen touches the string, and it makes a tiny blurt of sound. He is startled but pleased, and he touches it again. “Rub it hard,” says the woman behind you. Allen laughs and bites his hand, then reaches again to pull with more force. A low vibration starts, then swells and rises as Allen strokes again and again, bringing all the harmonics of the long string to life. He plays a neighboring string, using his whole weight, triggering vibrations that bounce off one another and overlap in huge waves of sound. Excited by his success, he roars exuberantly along with the music. He has no intention of stopping now.

You meet the eyes of the woman behind you. Somewhere inside both of you, a laugh begins. Your bellies jiggle; you cover your mouths, but the growing mirth erupts into a wordless dialogue. Allen whoops, and the rich pitches of the harp reverberate from the earth to the heavens. Beyond the clamor, you can just make out the pitter-patter of the crowd’s applause.