“The print on your wall, Jaarsma. I feel like I should recognize it.”

He smiles, pushing his chair back, stands and walks to the other side of the room. Gail follows closely behind him, wondering whether to pause the tape. She lets the recording continue, taking care to ensure that the wires of the microphone stay clear. Framed beneath the glass, the pictures, six in total, are strange and wild. They hint of seahorse tails, the spiral of a winding nautilus, electric sparks.

“The Mandelbrot Set,” Jaarsma says, running his fingertips over one of the prints. “A collection of points derived from the quadratic equation z = z2 + c. The equation itself is very simple, but the Mandelbrot Set is one of the most complex objects in mathematics. See this boundary here,” he says, indicating a shape enclosed by a band of colour. “Any part of this edge, this cartoid, no matter where, no matter how small, will, if magnified, reveal new points. And these, if further magnified, will also reveal new points, ad infinitum.”

Gail moves closer to the wall, gazing at the pictures. Each successive print is a magnification of a detail of the last. The last frame is labelled as being a ratio of 1:1 million.

“The boundary encloses a finite area, but the boundary itself is infinite. No matter how much we increase the magnification, the same shapes appear and reappear in the border, though never quite the same. The image reveals a kind of symmetry, not of left and right, but of large scales and small ones.

“Imagine that we are standing here,” he says. Unexpectedly, he takes her hand, ever so gently, and places it on a corner of the print. “I can imagine what the rest of the picture is like because this is a fractal image, and it is self-similar. It repeats. But to imagine the entire picture is akin to standing on a street corner and trying to imagine what England looks like from an airplane, or from Mars. I can extrapolate, but what I see at this level may not conform to my expectations of what it will look like as we move in space and time.

“Do you know how birds fly in formation? As far as we know, they hold no picture in their minds of the V formation, let alone the vast pattern of migration. They are aware only of the other birds in their immediate proximity. And the same is true for me; I respond to what is immediately around me. But the pattern that I cannot see, that I have no knowledge of, exists. My mind, my brain, is not made to imagine distances of great magnitude. Or infinite time, eternity. We glimpse a part of the puzzle and intimate, however vaguely, an answer. But if I read a book about geography, or the history of the Earth, or the universe, for that matter, how does that change the way I place myself within this formation?”

She gazes at the boundary, the intricate details. “It changes nothing and everything.”

Jaarsma smiles, delighted. “Precisely.”

She turns off the recorder and removes her headphones. “If I wanted to find someone in the Netherlands,” she says, “how would I go about it?”

He is taken aback by the question. “The telephone book?” he says, finally, not sure if she is serious.

“There is someone I want to find.”

Jaarsma walks across the room to his computer. He opens a browser and enters a Dutch Internet address. When the page has opened, he looks up at her, fingers resting on the keyboard.

Gail retrieves her notebook from her bag and opens it to the last page, where she had written, this morning, the name that she cannot shake loose: Sipke Vermeulen. Jaarsma studies the page, then types in the words. Almost instantaneously, an address and phone number appear on the screen.

That night, Gail stays awake. Her suitcase is open, the contents still neatly packed. Jaarsma’s translation of the diary is open before her, twelve pages of single-spaced type. William Sullivan, she thinks, all his thoughts transcribed into numbers, multiplied and added to themselves, a testament to what a person might do to make all their words disappear.

She imagines him working with pencil in hand, copying the numbers onto a sheet of looseleaf. Over and over, he erases his numbers and begins again. How is it possible to forget pain, to be unable to recall something that was once so inescapable?

In the diary, there is no detailing of violence witnessed and endured, of friends executed, of resistance. That, in the end, is what Gail finds so startling. She knows, through her research, that in the Hong Kong camp, a third of the men died before the war ended. In the prisoner-of-war camp in Sandakan, only six of three thousand men lived to see liberation. William Sullivan kept the diary as proof of a different kind of existence, where part of him still saw the world as if he were free. He wrote about their rituals, what time they got up in the morning, the kind of trees that grew outside the camp, the food they ate, the girl smugglers who passed by outside. “Some are as young as ten years old. Their clothes hang together with invisible thread.” And another entry: “My most prized possession is a set of three tin dishes. They came to me through various hands, and they are useful for all sorts of things. Food, chiefly. But also to gather leaves for tea, to hold on to a bit of water. They are valuable also because, in a time of necessity, they can be traded for pills or medicine.” Through these sentences, these pages, he would make the world cohere.

For three years, the men in the camp were starved and brutalized, treated as less than animals, but he had continued the journal, as if through it he could maintain some part of his dignity. In entry after entry, he imagines the days to come. “When I see you next,” he writes, addressing Kathleen’s mother. “After the war is finished.”

When the camp was liberated in August 1945, he had been twenty-five years old. Gail had learned that the physicians and psychologists of the time had all agreed: the war was finished, these men who had survived should go on with their lives in the best way possible. They should not burden their families with the misery of what they had endured. So he had gone on, honourably discharged from the army, and he had kept his silence.

Earlier, she had telephoned the number for Sipke Vermeulen. The voice of an elderly man had answered, his words clear and lightly accented. When she said her name, a silence followed, and she feared the conversation had come to an end, that Sipke Vermeulen would put down the phone, without her understanding the reason why. But then time had begun again. He had repeated her name, in surprise, in recognition.

Arrangements were made. Sipke Vermeulen had told her he would come down to Amsterdam in two days’ time, and then they would travel up north together to his home in rural Friesland.

Jaarsma had been standing in the window, watching the moonrise, the gleam of light clouding the city. He had poured two glasses of wine and ordered dinner from the neighbourhood Indonesian restaurant, sticks of satay, babi pangang, a container of rice. When he looked at her, his face held a question. She told him about the letter that she had found years ago. She wondered if it was possible to know a person truly. And if we did, would we know what we had, would we recognize it?

At one point in the evening, Jaarsma had put his fingers to the window, indicating the light. He told her that people believe that the moon changes in size as it moves across the sky, becoming larger and fuller as it nears the horizon. But the size of the moon, he said, remains constant no matter where it is, and the idea of a larger moon is an optical illusion. We could measure it, he said, with a paper clip, shaped into a caliper. He still remembered the day his father, an astronomer, told him this fact.

“And what did you feel,” Gail had asked him, “when you learned it was only an illusion?”