From the Agreement of Temporary Cooperation, Clause 4: "Neither Party shall enter the other's residence after nine o'clock in the evening. No exceptions."

The task was a product, and Wenxi had the idea on a Tuesday.

She came into the workshop at seven in the morning, before the light had properly cleared the roofs, with a tray balanced on one arm and a look on her face that he had not seen since she was fifteen and had discovered that sugar could be made to hold a shape. She did not say good morning. She put the tray on his bench, between a half-planed board and a tin of nails, and stepped back.

On the tray sat a single cake.

It was a small round one, pale gold, about the size of a plum. It was perfectly plain. It had no pattern at all, only a faint dusting of rice flour, and a slightly pitted surface where the dough had stuck in the mould, and he saw at once what was wrong with it. The mould she had used was one of the old ones from the shop wall, a carved lotus, worn and shallow with a hundred years of use. It had given her a cake with a ghost of a flower on its face, like a name half rubbed out of a stone.

"The campaign wants a combined product," said Wenxi. "Something that belongs to both trades. Tang Rui says it has to be sold at the festival, with both our names on it, and the judges are going to taste it. And I have been lying awake for three nights, and I think I have it."

"A mould," said Chengyan.

She stared at him.

"That's what you were going to say."

"It was going to be a surprise."

"It's a very obvious surprise. The old ones are worn out. You've been using that lotus since the year you came home, and it can't hold an edge." He picked up the cake and turned it in the light. "If it were cut again, properly, in new wood. Pear, or boxwood. Very hard. It would last a hundred years."

"And the pattern," said Wenxi, "would be yours."

She said it quickly, as though it were a thing she had been afraid to say. Her cheeks had gone pink. She stood with her hands pressed together in front of her, and he saw that she was holding her breath, and that her whole attention was fixed on his face.

He set the cake down.

"I haven't carved a mould in four years," he said.

"I know."

"I'm not a carver. I'm a joiner. It's a different hand."

"I know that, too."

"I could ruin it."

"Chengyan," said Wenxi, quite gently, "you have never ruined a thing in your life that you didn't mean to."

He thought of the cedar plank, the gouge across the grain, the morning she came with the box of dumplings. It did not seem the moment to mention it.

"All right," he said.

He started that night.

It was past ten when he shut the doors. Zhaoyu had gone home, grumbling, to a bowl of noodles and a bad film. His grandfather was asleep. The workshop lay quiet and warm and smelling of oil, with the lamp pulled low over the long bench and a block of pale boxwood clamped in front of him, no bigger than the palm of his hand. He had chosen it himself at the timber yard. It was close and creamy and very dense, with a grain so fine it was almost invisible, and when he ran his thumb over it, it felt like cold ivory.

He laid out his tools in a row: the little chisels, the gouges, the knife with the horn handle that had been his grandmother's. He drew a circle on the wood with a compass. Then he sat for a long time with the pencil in his hand, looking at the empty round.

The obvious thing was the plum blossom. He had carved one in the corner of the tray at Round One, a thing the size of his thumbnail, and it had cost him a week of sleep. He knew the shape of it by heart: five round petals, a tiny stamen, a stem bending down to the left. It was the pattern on Grandma's best mould. It was the pattern on the box. It would have been the right pattern for a shop with a hundred years of history and a pot of tea on the table.

He drew it. He drew it well.

Then he looked at it, and rubbed it out with the heel of his hand, and sat there with a grey smear on his palm.

It was too familiar. It was a plum blossom. Every grandmother in the river country had a plum blossom. It was the safest pattern in the world, and he found that he could not make his hand cut it, because he did not want a mould that said we were here a long time. He wanted one that said, here is a thing no one has made before.

He started again. A swallow. A lotus. A fish. A coin, in the old style, with a square hole. Each of them came out neat and correct, and each of them he rubbed out, until the block was a grey blur, and the clock in the kitchen struck midnight, and then one.

It was in the small hours that he found himself drawing a line.

It was not a pattern. It was only a vertical stroke, near the edge of a scrap of paper, and beside it a small notch. Then another stroke, a little higher. Another notch. He drew them without thinking, the way a man whistles, in two columns, the one on the left a little higher than the other. He was at the fifth pair before he realised what he was doing.

He looked at it.

He set the pencil down. Outside, in the alley, a cat yowled and was answered.

"You're drawing her," said a voice behind him.

He did not jump. He had known for some time that someone was in the doorway. Zhaoyu stood with his hair on end and a bowl in one hand, in a vest and pyjama trousers printed with small green frogs, regarding the paper with an expression of the most intense and blissful interest.

"It's measurements," said Chengyan.

"Of whom?"

"Of nobody."

"Those are a girl's heights. Look, there's a date. That's a sixth birthday. I know that she was six. I have the spreadsheet." Zhaoyu advanced into the room with the reverence of a pilgrim. "You have been carving a mould for four hours and you have drawn her heights. Yan-ge, I am not saying anything. I am only saying that I was going to go to sleep, but now I am going to stay awake for the rest of my life."

"Go to bed."

"I could hold the lamp."

"Go to bed," said Chengyan, "or I will give you the cat."

Zhaoyu fled. They heard him stumble in the passage, laughing in a high, weak, delighted way, and then a door banged, and the workshop was silent again.

Chengyan sat with his elbows on the bench and his hands over his face. After a while he took them away.

The paper lay under the lamp. Two columns of small strokes, going up. And above them, in the grey rubbed smear where the plum blossom had been, he saw something he had not meant to draw at all: two long thin curves, drooping down from the top of the circle, with narrow leaves along them, like the hair of a woman bending over water.

They crossed. At the centre of the block, the two branches wound over and under one another, once, twice, three times, in a loose slow plait. At the foot, the tips came out together and lay side by side.

It was a willow.

He had been carving it on paper for four hours without knowing. One branch for the left of the tree and one for the right. And the leaves, the narrow pointed leaves, falling in a fringe around the rim, each of them a tiny stroke, like a notch.

He picked up the gouge.

He worked until dawn. He did not stop for food or for tea. The knife bit into the boxwood with a small clean whisper, and the wood came away in curls as fine as eyelashes, and under the lamp the willow came up out of the block, branch by branch, leaf by leaf, as if it had always been inside and only needed telling. He cut the two main branches deep, as deep as the cake would take, so that the dough would swell into them and hold their shape. He cut the leaves shallower. At the centre, where the branches crossed, he went slowly, with the smallest chisel, with his tongue between his teeth, because there was no second chance. A slip there and the whole plait would collapse.

He did not slip.

When the first light came grey through the high window he laid down the tool and sat back, and his hands were shaking, and he did not know when it had started.

It was not finished. The edges wanted smoothing. The back wanted a handle. But it was there, in the cream-coloured wood, a thing that had not been in the world the day before: two branches growing from a single root, bending toward one another, and crossing, and going on.

He turned the block over and, on the back, in the lower corner, where nobody would think to look, with the point of the finest knife, he made a row of tiny notches. Eleven on the left. Eleven on the right.

Then he put his head down on his arms, on the bench, and slept for twenty minutes.

She came at four in the afternoon.

He heard the hitch in the step. He was at the lathe, turning a short handle of pear, and he did not look up. He heard her stop at the open door. He heard her not say anything.

"Come in," he said.

"I brought dough."

She had a covered bowl in the crook of her arm and a smear of flour across her forehead. She was wearing the old blue apron. She came into the workshop slowly, as she did every time, with her eyes going round the room like a woman entering a church. Then they came to the bench, and rested there, on the small pale block lying under the lamp.

She stopped.

He turned the lathe off. The silence rushed in. He wiped his hands on a cloth, and stood, and did not know where to put them.

"It isn't finished," he said. "The handle isn't on. I'd meant to sand the rim, and there's a, "

"Chengyan."

"Yes."

"Be quiet."

He was quiet.

She crossed the floor. She put the bowl down very carefully on the end of the bench, as if it might break. Then she bent over the mould, with her hands behind her back, as one does over a child asleep in a cot, and looked at it.

She looked at it for a very long time.

He counted her breaths. He lost count. The light came through the high window and lay on the wood, and the willow stood up out of it in tiny shadows, branch over branch, and the fringe of leaves ran round the rim like a row of stitches. He saw her follow the plait with her eyes. He saw her reach the place where the two crossed, and go back, and cross it again.

She did not say a word.

He had been afraid of many things in his life, and most of them could be named. He was afraid of the roof, and the cost of the roof. He was afraid of the day his grandfather would stop being able to climb the stairs. He had been afraid of a letter in an envelope from a city he would never see. But he thought, standing there in his shirtsleeves with the sun on the sawdust and a woman he had loved for most of his life bent over a piece of wood, that he had never been afraid of anything so much as this silence.

She picked up the bowl.

She took off the cloth. Inside lay a ball of pale dough, still faintly warm, smelling of honey and toasted rice. She pinched off a piece. She rolled it between her palms, quick and neat, into a round ball, dusted it with flour, and laid it in the carved hollow of the mould. Then she took his mallet from the bench, the small boxwood one, and tapped the back of the block, twice, three times, softly.

She turned it over.

The cake came out whole, with a faint sigh, into her hand.

It was perfect. The willow stood up on its face in high golden relief, every leaf distinct, every branch crisp, the two long drooping stems winding over and under one another and crossing, and crossing, at the centre of the round. In the light from the window it looked like something that had grown there.

She held it in her palm. She said, in a voice he had never heard before, rather small and rather odd, "It's the tree."

"Yes."

"It's the willow."

"It was the only thing I could think of."

"There are two branches."

"Yes."

"They cross."

He did not answer.

She turned the cake over, gently, and looked at its smooth back, and then at the mould. Her thumb moved along the underside of the block, slowly, along the edge, and stopped. She tilted it to the window. He saw her find them: the tiny notches in the corner, eleven and eleven, so small that you would need a lamp to see them.

She did not ask what they were. She had known the moment she saw them.

"You said nobody would look," she said, so quietly that he nearly missed it.

"I didn't say anything."

"No." A pause. "You didn't."

The cake lay in her hand. She was not looking at him, and he thought that her eyes were bright, though it might have been the light. She stood like that, quite still, with the mould in one hand and the golden willow in the other, and the dust turning slowly in the air around her.

Then she held out the mould to him.

"I can't take this," she said. "Not for the campaign. It's, it's too, it should be yours. For the workshop. You made it."

"It's for the shop," said Chengyan.

"Chengyan, "

"For your grandmother's shop. It should be in Su Ji. On the wall, with the old ones." He pushed it gently back into her hands. His fingers closed over hers for a moment and let go. "It's yours."

She looked at it. She looked at him.

Then she did something he did not expect. She set the cake down on the bench. She wiped her palms on her apron, slowly, one and then the other. She lifted her hands, held side by side with the palms up, the way she had once taken a cup of holy water at a temple at the age of nine, and he saw them tremble, just slightly, and steady.

He put the mould into them.

She took it with both hands, as one receives a certificate, or a sleeping bird, or a vow. She held it against her chest, and bowed her head over it, so that he could see only the parting in her hair and a thin curl of pine, caught there still from the day before.

"Thank you," she said, to the wood.

He could not speak. He nodded, although she could not see.

They stood in the long gold afternoon without moving, and the lathe ticked as it cooled, and a bee wandered in at the window and out again. Somewhere beyond the wall, in the kitchen of Su Ji, an old woman had begun to hum.

She stayed to make twelve more.

That was how it happened. She had meant to go back to the shop, and then there was dough left, and then there was more dough, and then he fetched the little brazier from the back and they set the tray on the bench and baked them there, one batch at a time, in the workshop, among the shavings. They tasted each one. They argued about the proportion of honey. They found a flaw in the left-hand leaf of the second branch, which she said was a feature, and he said was a crack, and she said that cracks were what made a thing real. They ate eleven of the twelve and put the last on a plate for Zhaoyu, who would not deserve it.

He lit the lamp. He did not notice that he had.

The light outside went from gold to rose to violet, and he saw her through it, perched on the corner of the bench with her legs swinging, as she had perched at sixteen, with a smear of honey on her thumb and the mould on her knee. She was talking about the festival, and the boats, and a ridiculous hat that Tang Rui had made her promise to wear. He was listening. He was leaning on the lathe with his arms folded and the corner of his mouth tucked in, and he thought, quite calmly, that he would like this to be the whole of his life.

She stopped talking.

She was looking at the clock above the door, a round, dim, brown-faced thing with a cracked glass that had hung there since before he was born.

"It's ten past nine," said Wenxi.

"Is it?"

"It is." Her mouth was doing something peculiar. "Clause Four."

"This is a workshop."

"It's attached to your house."

"It is a place of business."

"Your bed is through that door," said Wenxi, pointing, "and you are standing on a rug that your grandmother knitted. I can see your slippers."

He looked at the slippers. They were by the stove. They were enormous and tartan and entirely damning.

"No exceptions," she said, with enormous satisfaction. "It's underlined three times. I did it myself."

"I am working," said Chengyan.

"You are baking cakes."

"I am testing a tool."

"You are sitting in the lamplight eating honey with a woman, and you have not mentioned the hour once."

"I haven't," he said, "been looking at the clock."

It came out lower than he had meant. It stopped her. She sat very still on the corner of the bench with the mould in her lap, and her smile faded gently to something quieter and a little amazed, and he thought, I have said it, and the sky has not fallen.

"No," said Wenxi. "I don't suppose you have."

The lamp hissed. A moth beat its soft wings against the glass.

"I should go," she said.

"Yes."

"It's the clause."

"It's the clause," he agreed.

Neither of them moved. She looked at the mould in her lap. He looked at the slippers. And outside, in the dark beyond the open door, the hum in the kitchen of Su Ji changed key, and rose, and settled into the thin, bright, unmistakable shape of a wedding song.

"I'll walk you to the gate," said Chengyan.

"It's thirty paces."

"I know how far it is."

He took the lamp.

They went out into the cool blue dark, side by side, with the little light swinging between them and throwing their shadows long and thin on the bluestone. Neither spoke. She held the mould against her chest. At the third flowerpot she stopped, and turned, and the lamp lit the underside of her face, the soft curve of her chin, the shine of her eyes.

He thought she would say goodnight.

She said, "Eleven and eleven."

He did not breathe.

"I counted," said Wenxi. "On the back. That's twenty-two marks. I only had seventeen on the paper."

"I carved the rest from memory."

"You stopped at seventeen," she said. "The last year we measured." Her voice cracked. "Why did you add the others?"

He looked at the lamp. He looked at the dark mouth of the alley and the first stars above the roofs. He had a hundred answers, and every one of them was a clause.

"Because it didn't seem finished," said Chengyan.

She put her hand on the gate. She stood there with her back to him, and the willow mould pressed to her heart, and he saw her shoulders rise and fall once, slowly, in the lamplight.

"Goodnight, Chengyan," she said.

"Goodnight."

The gate clicked. He stood in the alley with the lamp in his hand until her light came on in the window above the kitchen, small and yellow, behind the tall dark shape of the jasmine. Then he went back to the workshop and sat down at the bench in front of the empty block of boxwood, and for a long time he did not do anything at all.

He had lied. He had said that he had not been looking at the clock.

He had been looking at it all evening. He had simply been hoping, with a patience that frightened him, that it would stop.