Mr J. L. B. Matekoni snorted. ‘That thing never goes away, Mma. There will always be somebody prepared to pay those people to put a curse on his enemy.’

‘Don’t the police do anything about it?’

Mr J. L. B. Matekoni scratched his head. ‘If they hear about it; but nobody wants to report it to them. It is always the same. Fear works.’

Mma Ramotswe agreed, but her fundamental question remained unanswered. What sort of person would do such a thing?

‘Let me put it this way, Rra,’ she said. ‘If you received a feather or something like that, whom would you suspect?’

He answered quickly. ‘My enemies.’

‘But you have none, Rra.’

He looked puzzled. ‘Perhaps not. But if I did, then they would be the suspects.’ He paused. ‘Or a rival, I suppose. Anybody can have rivals.’

They were silent for a while, and Mma Ramotswe stared out of the window at the acacia tree. A small bird – not one of the doves who made their home there, but something altogether more modest – was arguing with another bird about the possession of a few inches of branch. The prize was nothing much, and there were plenty of unoccupied branches nearby, but for the birds it was worth fighting for. She watched the birds in their tiny rage, and was joined by Mr J. L. B. Matekoni, who stood at her shoulder.

‘Ridiculous birds,’ he said. ‘They are always squabbling with one another.’

‘Like people,’ muttered Mma Ramotswe. ‘We are always fighting too – over the same things that animals fight over. Land. A place to live or work.’

‘Maybe.’

‘Yes, we are. And the people who are in a place first think that this means that everybody else can be shooed away. Like that bird over there. He was there first, he says. The other bird is the intruder.’

He was thoughtful. They both knew what was being discussed. ‘But don’t people have the right to protect their place? This Botswana of ours – everybody would want to come and live here. All those people from countries where things don’t work, or where they are in a big mess – they would want to come here. And we couldn’t manage that, Mma Ramotswe…’

She understood the point he was making. You could not open your doors to everybody because you would go under if you did. So you had to harden your heart; you had to be selfish, which she did not like. But you cannot turn another away, she thought; you cannot.

‘It is very hard,’ she said. ‘But I suppose you’re right. We cannot take on all the problems of Africa. Nobody can.’ That was true, she realised, though she wished that it were otherwise.

She looked again at the birds. Mma Soleti was the bird that had come to the tree more recently. The other bird, the defender, was the bird that was already there.