There he stood in his white robe and prayer hat, as magnificent as a maribout, tapping the blackboard with his cane. On the desk beside him was a small book with a smart cover of tanned camel hide. Mariama smiled. She knew what that book contained and she could not even look at it without feeling a shiver in her stomach.

The students were ranged in rows on benches. Women wearing brightly patterned headscarves and children in outsized T-shirts and some men too, all gazing up at Ousmane as though he brought revelation from God himself. Mariama stood at the back of the class and surveyed the clusters of words on the board. She did not know what they meant, nor did she need to. She was here because she liked to watch her husband teach. And to keep an eye on the book, of course.

Ousmane pointed with his cane to words on the board and the students read together.
Tap, tap, tap.
"Man, wife, hut!" chorussed the class.
Tap, tap, tap, tap.
"Child, chicken, sheep, cow!"

Her husband was no longer a young man but he was still strong, and the light of intelligence shone as bright as ever in his eyes. He turned to the board and began to write, and Mariama's eyes wandered again to the book.

She had found the money yesterday while dusting. In harmattan season the air was thick with red dust and cleaning in the hut was hard work. She always started with the straw mats, the cooking pots and the gourds, and then she did her husband's things - wicker chair, prayer mat, lamp and books. Yesterday morning she had dropped the camel-hide book and picking it up she noticed the corner of a blue sticking out of the inside cover. She rummaged. There were six blues in all and two greens. They smelled of tobacco smoke and camel hide.

Mariama had seethed as she replaced the notes. She had never dreamed that her husband earned so much from his teaching. Why had he never told her about this money? Why did he never spend it? At the market this month there were plump red mangoes and sweet bananas, but the money Ousmane gave her was enough only for millet and baobab leaves. They did not have animals either, unless you counted the chickens. How could he do this to her?

She had not needed to wait long for an answer. Whilst washing her hair behind the hut later in the day she had overheard Ousmane talking inside with their neighbour Tidjani.
"I can't come with you, Tidjani," her husband was saying. "I am saving."
"For your wife?"
"That's right."
Behind the hut, Mariama straightened up quickly and lifted the curtain of wet hair away from her ears.
"Are you being wise?" said Tidjani.
"Shh - she will hear us."
"You mean she does not know yet?"
"Not yet."

The light in the classroom was fading. Students chattered in low voices. A gecko clicked. Old Halimata Siise got up off her bench, made her way slowly to the side of the class and spat out of the window. Ousmane continued to write. Mariama watched him and thought of those six blues and four greens lying in their dark hiding-place so close to them both. Her husband's money. Her money.

Mariama had not let on that she knew about her husband's savings, but wasted no time in dropping hints about what she most wanted.
"Oussou," she had murmured in his ear as they lay together last night, "if you bought me a cow, we would drink milk every day. We would eat our millet dumplings with baobab leaf sauce, and then I would mix the leftover dumplings with fresh milk and we would eat that also, and I would grow fat and beautiful."
"You are already beautiful," said Ousmane, twining one of her silky braids around a middle finger.
"But not fat," she said sadly. "I want a cow more than anything in the world, Oussou."
He released his finger and his voice was harsh. "It is written, Mariama: to eat dry bread, to drink pure water and to sleep upon the ground more than suffices him who wishes to inherit paradise."
"Him, perhaps - not her," she muttered, but straight away she felt ashamed of herself. Ousmane was saving up his hard-earned blues to buy her something special, and here she was haranguing him. She resolved not to mention the cow again for at least a week.

Ousmane stepped away from the blackboard and faced the class. The students gazed up at the new words.
"One child," he said.
"One child!" said the class.
"Two children," he said, pointing.
"Two children!" said the class, and the mothers amongst them beamed at each other.
Mariama looked away. She could not go anywhere without seeing babies. They seemed to leak out of every hut in the village, guzzle at every breast, vomit on every straw mat. Even here in the literacy class, they clung to backs and bounced on laps and wriggled naked on the floor. When God willed it, Mariama told herself, she too would conceive. In the meantime, she must not give way to hate.
Tap, tap.
"One chicken, two chickens!" sang the class.
Tap, tap.
"One hut, two huts!"

Two huts. What was it Ousmane had always told her? "The world is like a bridge, Mariama. We pass over it, but we should not build on it." Yet Donkey-cart Seydou had turned up at the yard this very morning to deliver four hundred mud bricks.
"What are they for?" Mariama had asked him.
"Your husband wants another hut," said Seydou, piling the bricks in the corner of the yard.
"We do not need another hut."
Seydou shrugged, careful not to meet her eyes. "Perhaps your husband wants it for a millet grinder."

Standing at the back of the classroom in the waning light, Mariama considered what Seydou had said. So the extra hut was for a millet grinder, was it? It made sense. Every afternoon she stood for three hours with her pole and mortar, and pounded millet into flour for the dumplings. A grinder would save her aching arms and back, and her neighbours would be able to use it too. Most of them would happily pay 20 francs a tin to have their millet ground by a machine. If Ousmane bought her a millet grinder, she would soon make enough money to buy a whole herd of cows. Think of all the milk! She would be the fattest woman in Burkina Faso.

The earthen walls of the classroom were suddenly suffused with soft gold light - three or four golden minutes, thought Mariama, and then it will be dark. The class was practising today's reading, and as they got more confident, Ousmane picked up speed. Tap, tap, tap, went his cane, faster and faster. These literacy lessons always built to a chaotic and hilarious climax which Mariama loved. She began to tap her foot in time to the cane.
Tap, tap, tap.
"One man, two men, one sheep!"
Tap, tap, tap, tap.
"One sheep, one chicken, two chickens, two cows!"

Some of the students were keeping pace, others were already lost. Old Halimata Siise threw up her hands in bewilderment and collapsed chuckling on her neighbour's shoulder. Still Ousmane danced to and fro, twirling and tapping his cane, his spotless robe whirling about his ankles.

Mariama was reminded of her wedding day - the patter of the tamtam, the thud of the balafon and Ousmane dancing until he could hardly be seen for the dust. Still dancing, he had brought the bride-price to her father, a sum so great that he had needed two gourds to carry it in. How proud she had been. She had sworn before the maribout and all the guests that she would submit to the will of God and the will of her husband all the days of her life. That was seven years ago.

The golden light had faded into grey and Ousmane's face was now in shadow.
Tap, tap, tap! "One hut, one wife, two chickens!"
Tap, tap, tap, tap! "One hut, two huts, one wife, two wives!"
Mariama frowned. Somewhere nearby a baby chuckled.
Tap, tap, tap, tap! "One wife, two chickens, two wives, two children!"

She stared at the camel-hide book. The events and conversations of the past days reeled in her mind. She raised her hand to stifle a sob.
Tap, tap, tap, One hut, one wife, two chickens, Tap, tap, tap, tap, Two huts, two wives, two chickens, two children.

It fitted. Mariama now knew beyond all doubt what her husband was saving for. She backed out of the classroom, turned around and fled into the darkness. Even when she got to the edge of the well she could still hear the relentless tapping and chanting and lunatic cackling behind her.