We go first to Sloan Kettering's main campus. I was here three years ago, when she had her cancer surgery, a procedure called, with a bracing absence of euphemism, debulking. I trail my mother as she wends expertly now through corridors, up and down elevators, in and out of various reception areas, office suites and locker rooms. Registration. X-ray. Waiting room. Examining table. I am overwhelmed by the ease with which she navigates, the ease with which she greets technicians, doctors, nurses, fellows. Inquiring about their families. Joking with them about the weather, the scheduling mishaps, the broken light fixture, their bedside manners. I am a little in awe of her confidence and grace. I think I am getting a taste of what a parent must feel like, visiting her child at college for the first time, getting a tour of the dorms, the classrooms, the quad. A new world that is alien to the parent, utterly familiar to the child. Except she is the parent and I am the child.

We must hurry through these appointments because my mother has chemo scheduled at the 53rd Street clinic at noon. Of course, the phrase "we must hurry" is meaningless, as my mother is not in charge of the pace. She delivers herself to these buildings, these rooms, where she is repeatedly instructed to wait. At last her morning appointments are over and she guides us through a rabbit warren of not-quite public space, basement tunnels populated mostly by people wearing official badges and uniforms or white coats, until we come out on the other side of the building, on First Ave., just in time to catch the jitney, a jolly word. It's parked at the curb, a little gold bus that runs between the main campus, the parking garage, and 53rd Street. Ordinarily my mother would walk to chemo from here, nearly 20 blocks, but today there is the issue of time. We board, sit, look out the window. Outside the rain is still spattering. I can feel her wanting to be in it, wanting to walk, feel the unseasonably cool summer air on her face, feel the drops of rain.

In front of us sit a man and a little boy. I think they may be grandfather and grandson. Who is sick, I wonder? Who have they been visiting? The grandfather says, with interest, "Look out there! See that?" A little white terrier wearing a lime green raincoat.

Two white men in their forties sit side by side, one tall, one short. The short one complains in a loud voice about the pharmacists at Duane Reade. He complains in a loud voice about the rain. In a loud voice, he asks his partner how he feels. Through all of this the partner says nothing. I don't see his face, only the back of his thin neck. The short man leans over and gives the tall man a kind of contorted jitney-embrace. "You're cold," he says in a loud voice. "We'll get you a blanket when we get home."

At 53rd Street, I follow my mother inside, past the waterfall in the lobby, past the basket of fat round hard candies on the reception desk. I have been here once before, with my children, who were terribly impressed by the waterfall, and even more so by the basket of fat round hard candies.

Here again, my mother is some kind of connoisseur, a tour guide in what has become her own country: graceful, swift, smiling, expert. We board the far elevator: less congested. She manages to check in with the receptionist who is the friendliest of them all. In the waiting room, she finds seats by the window, where we can see the rain.

I meet Harriet, her friend, also waiting for chemo. Harriet is beautiful, tall and straight. Her features are delicate and clear and her face seems very focused, in the manner of a lighthouse beam. My mother met her a few years ago, while waiting for one of her first chemo sessions. Harriet has the same kind of cancer as my mother. When my mother received her diagnosis, she learned that half the people with advanced ovarian don't live much more than five years past diagnosis. Harriet's in her eleventh year. It was Harriet who told my mother, the first day they met, that she didn't worry about her health. If there was any evidence, she said, that suggested worrying might help, even a little, she would by all means go ahead and worry.

The greatest worry may be erasure. The slow, steady draining away of presence, of mattering, of selfhood. At home my mother has made a photo gallery - a modest assemblage of a dozen pictures scotch-taped to the door leading to the garage. Photo of socks she has been knitting. Photo of grass she grew in a basket. Photo of a string of origami cranes she made as a graduation present for her oldest granddaughter. Photo of herself, teaching a card game to her youngest granddaughter. Photo of her and my dad. Photo of herself scattering her own mother's ashes in the north woods just last month. Things she has made, things she has done, people in whose lives she figures explicitly, crucially. It's a form of documentation, she says. Evidence that she is still in the world. Evidence that she still is, active verb , in the world.

Late in the day, chemo finishes. Out the window, down below, rush hour traffic has begun. The cleaning crew has wheeled out mops and buckets. In the waiting room, people are still waiting to be called in for treatment. We ride the elevator down, and passing through the lobby overhear the tail end of a conversation. A middle aged black security guard is talking to an elderly white woman in a head scarf. He is saying, "I missed you. Take care of yourself. I love you, darling."

My mother tells me one time she arrived for a chemo appointment and the young man in the reception area keyed her name into his computer only to pronounce, "No record of you."

My mother reenacts how she gasped, how she brought a hand to her chest. "Really?"

"No, just joking."

"That's a terrible joke," she said she told him, but trying to smile through the words, trying to recover her equilibrium even as her heart sped up, even as the great dread continued to flood her veins. She didn't want to burden him with the weight, the understanding of what his words had done.