"Well, then?" Niccoli urged, studying him with a frown.

"I'd like to write a dissertation on the zeros of the Riemann zeta function," said Mattia, staring at the professor's right shoulder, where a dusting of dandruff looked like a little starry sky.

Niccoli made a face, an ironic smile.

"Excuse me, but who are you?" he asked without concealing his disdain and locking his hands behind his head as if wanting to enjoy a moment of fun.

"My name is Mattia Balossino. I've finished my exams and I'd like to graduate within the year."

"Have you got your record book with you?"

Mattia nodded. He slid his backpack off, crouched on the floor, and rummaged around in it. Niccoli stretched out his hand to take the book, but Mattia preferred to set it on the edge of the desk.

For some months the professor had been obliged to hold objects at a distance to get them properly into focus. He quickly ran his eyes over the sequence of high grades. Not one flub, not one hesitation, not one try that had gone wrong, perhaps on account of a love story that had ended badly.

He closed the book and looked more carefully at Mattia. He was dressed anonymously and had the posture of someone who doesn't know how to occupy the space of his own body. The professor thought he was another of those who do well in their studies because they are unable to make much headway in life. The ones who, as soon as they find themselves outside the well-trodden paths of the university, always reveal themselves to be good for nothing.

"Don't you think I should be the one to suggest a topic for you?" he asked, speaking slowly.

Mattia shrugged. His black eyes moved right to left, following the edge of the desk.

"I'm interested in prime numbers. I want to work on the Riemann zeta function," he replied.

Niccoli sighed. Then he got up and walked over to the white bookshelf. As he ran his index finger along the spines of the books he snorted rhythmically. He pulled out some typed pages stapled in one corner.

"Fine, fine," he said, handing them to Mattia. "You can come back when you've performed the calculations in this article. All of them."

Mattia took the stack of pages and, without reading the title, slipped it into his backpack, which leaned against his leg, open and slack. He mumbled a thank-you and left the office, pulling the door shut behind him.

Niccoli went and sat back down in his chair and thought about how over dinner he would complain to his wife about this new and unexpected annoyance.

Alice's father had taken this photography business as the whim of a bored little girl. Nonetheless, for his daughter's twenty-third birthday, he gave her a Canon SLR, with case and tripod, and she had thanked him with a beautiful smile, as impossible to grasp as a gust of icy wind. He had also paid for her to take evening classes, which lasted six months, and Alice hadn't missed a single lesson. The agreement was clear if implicit: university came before everything else.

Then, in a precise instant, like the line separating light and shade, Fernanda's illness had gotten worse, dragging all three of them into an increasingly tight spiral of new tasks, drawing them toward an inevitable cycle of apathy and mutual indifference. Alice hadn't set foot in the university again and her father pretended not to notice. A feeling of remorse, the origins of which belonged to another time, kept him from imposing his will on his daughter and almost kept him from talking to her at all. Sometimes he thought it wouldn't take much, all he would have to do was go into her room one evening and tell her… Tell her what? His wife was disappearing from life like a wet mark drying on a shirt and, with her, the thread that still connected him to his daughter was slackening-it was already scraping the ground-leaving her free to decide for herself.

With photography Alice liked the actions more than the results. She liked opening the back of the camera and unrolling the new film a couple of inches, just enough to catch it in the runner, and thinking that this empty film would soon become something and not knowing what, taking the first few snaps into the void, aiming, focusing, checking her balance, deciding whether to include or exclude pieces of reality as she saw fit, enlarging, distorting.

Every time she heard the click of the shutter, followed by that faint rustle, she remembered when she used to catch grasshoppers in the garden of their house in the mountains when she was a little girl, trapping them between her cupped hands. She thought that it was the same with photographs, only now she seized time and fixed it on celluloid, capturing it halfway through its jump toward the next moment.

During the course she had been taught that the strap of the camera is to be wrapped around the wrist twice. That way, if someone tries to steal it they're forced to tear your whole arm off along with it. Alice ran no such risk in the corridor of Our Lady's Hospital, where her mother was being cared for, but she was used to carrying her Canon like that anyway.

As she walked she grazed along the two-tone wall, brushing it with her right shoulder from time to time to avoid touching anyone. Lunchtime visiting hour had just begun and people were pouring into the hospital like a liquid mass.

Aluminum-and-plywood doors opened onto the wards, each with its own particular smell. Oncology smelled of disinfectant and gauze soaked in methylated spirits.

Alice entered her mother's room, which was the second to last. She was sleeping a sleep that wasn't her own and the gadgets to which she was connected didn't make a sound. The light was faint and drowsy. On the bedside table red flowers were arranged in a vase: Soledad had brought them the day before.

Alice rested her hands and the camera on the edge of the bed, where the sheet, lifted in the middle by her mother's outline, flattened out again.

She came every day to do nothing. The nurses already took care of everything. Her role was to talk to her mother, she imagined. Lots of people do that, acting as if the patients were capable of hearing their thoughts, able to understand who was standing there beside them, and conversing with them inside their own heads, as if illness could open up a different channel of perception between people.

It was not something that Alice believed in. She felt alone in that room and that was that. Usually she would just sit there, waiting for half an hour to pass, and then leave. If she met a doctor she asked for news, which was always the same anyway. Their words and raised eyebrows meant we're only waiting for something to go wrong.

That morning, however, she had brought a hairbrush. She took it out of her bag and delicately, making sure not to scratch her face, combed her mother's hair; at least the hair that wasn't squashed against the pillow. She was as inert and as submissive as a doll.

She arranged her mother's arms on top of the sheet, extended and parallel, in a relaxed pose. Another drop of the saline solution in the drip ran down the tube and disappeared into Fernanda's veins.

Alice moved to the end of the bed, resting the Canon on the aluminum bar. She shut her left eye and pressed the other to the viewfinder. She had never photographed her mother before. She pressed the shutter and then leaned a little farther forward, without losing the frame.

A rustling sound startled her and the room suddenly filled with light.

"Better?" said a male voice behind her.

Alice turned around. Beside the window a doctor was busying himself with the cord of the venetian blinds. He was young.

"Yes, thanks," said Alice, a little intimidated.

The doctor stuck his hands in the pockets of his white coat and went on looking at her, as if waiting for her to continue. She leaned forward and snapped again, more or less randomly, as if to please him.