“Even if their names are not their fault,” said Mma Makutsi, “the way those boys behave is their fault, Mma. There can be no doubt about that. And those boys are very lazy, Mma. They are examples of what I am talking about.”

She looked sternly at Mma Ramotswe, as if challenging her employer to contradict her. Mma Ramotswe did not rise to the bait; Mma Makutsi was rather assertive-and she admired the younger woman for that-but it did not help, she had decided, to engage with her too much when she was in mid-theory. It was best to let people have their say, she always felt; then, when they had finished, and had possibly run out of breath, one could always lodge a mild objection to what had been said before.

Mma Makutsi peered in the direction of the garage and lowered her voice. “Have you ever seen those two young men walking?” she asked.

Mma Ramotswe frowned. Of course she had seen the apprentices walking; they walked about the garage, they came into the office to collect their tea, they walked to the tree under which Mr. J.L.B. Matekoni's truck was parked. She pointed this out to Mma Makutsi, gently enough, but not so mildly as to prevent a firm refutation from the other side of the room.

“Not that sort of walking, Mma,” said Mma Makutsi. “Anybody can walk across a room or round a garage. Anybody, Mma. Even those two lazy young men. The sort of walking I'm talking about is walking from one place to another. Walking to work. Walking from the middle of town to the National Stadium. Walking from Kgale Siding to Gaborone. That sort of walking.”

“Those are not short walks,” said Mma Ramotswe. “Although it would not take too long, I think, to get from the middle of town to the Stadium. Perhaps twenty-five minutes if it was not too hot.”

Mma Makutsi sniffed. “How can we tell?” she asked. “These days nobody would know how long it takes to walk anywhere because we have all stopped walking, Mma. We know how long it takes to drive. We know how long a minibus takes. But we do not know how long it takes to walk.”

Mma Ramotswe was silent as she thought about this. She had long understood that one of the features of Mma Makutsi's speeches was that there was often a grain of truth in them, and sometimes even more than that.

“And here's another thing, Mma Ramotswe,” Mma Makutsi continued. “Have you heard of evolution? Well, what will happen if we all carry on being lazy like this and drive everywhere? I can tell you, Mma. We shall start to grow wheels. That is what evolution is all about.”

Mma Ramotswe laughed. “Surely not, Mma!”

But Mma Makutsi was serious. “Oh yes, Mma Ramotswe. Our fingers have evolved so that we can do things like typing. That is well known. Why should our legs not evolve in the same way? They will become circular, I think, and they will turn round and round. That is what will happen, Mma, if we are not careful.”

Mma Ramotswe could not keep herself from smiling. “I do not think that will happen, Mma.”

Mma Makutsi pursed her lips. “We shall see, Mma.”

Mma Ramotswe almost said: But we shall not, Mma Makutsi, because evolution takes a long time, and you and I shall not be around to see the results. But she did not, because Mma Makutsi's remarks had struck a chord within her and she wanted to think about them a bit more. When had she herself last walked any distance at all? It was sobering to realise that she could not remember. She usually went for a walk around her garden shortly after dawn-and sometimes in the evenings as well-but that was not very far, and she often spent more time looking at plants, or standing and thinking, than walking. And for the rest, she used her tiny white van, driving in it each morning to the No. 1 Ladies' Detective Agency and then driving home again at the end of the day. And if she went to the shops at River Walk, to the supermarket where there had been that dramatic chase with shopping carts, she drove there too, parking as close to the entrance as she could, so that she did not have a long walk across the car park. No, she was as good an example as anybody of what Mma Makutsi had been talking about. And so was Mma Potokwane, the matron of the orphan farm, who drove everywhere in that old van that they used to transport the children; and Mr. J.L.B. Matekoni, too, who was even more implicated in this epidemic of laziness, given that he fixed cars and vans and thereby enabled people to avoid walking.

No, Mma Makutsi was right, or, even if she was not entirely right, was a bit right. Cars had changed Botswana; cars had changed everywhere, and Mma Ramotswe was not at all sure that this change was entirely for the better.

I shall start walking a bit more, she resolved. It is not enough just to identify a problem; there were plenty of people who were very skilled at pointing out what was wrong with the world, but they were not always so adept at working out how these things could be righted. Mma Ramotswe did not wish to be one of these armchair critics; she would do something. She would start walking to work on… she almost decided on three days of each week, but then thought that two days would be quite enough. And she would start tomorrow.

On the way home that evening, the idea of walking came back to Mma Ramotswe. The idea returned, though, not because she remembered what Mma Makutsi had said about laziness, but because the tiny white van, which in the past few months had intermittently been making a strange noise, was now making that noise again, but louder than before. It happened as she made her way into Zebra Drive; turning a corner always put a strain on the tiny white van, which was something to do with the suspension and what Mr. J.L.B. Matekoni referred to politely as the “distribution of load.” Mma Ramotswe had pondered this expression and then asked, perhaps rather bluntly, “And the load, I take it, Mr. J.L.B. Matekoni, is me?”

He had looked away to cover his embarrassment. “You could say that, Mma Ramotswe. But then all of us are loads when it comes to vehicles. Even one of these very thin model ladies will be a load…” He trailed off. He was not making it any better, he thought, and Mma Ramotswe was looking at him in an expectant way.

When it became apparent that he had nothing further to add, Mma Ramotswe had continued, “Yes, Mr. J.L.B. Matekoni, there are such ladies. And unfortunately they are becoming more common. There are now many of them.” She paused. “But perhaps they will begin to disappear. They will get thinner and thinner, and more and more fashionable, and then… pouf… they will be blown away by the wind.”

This remark reduced the tension that had built, and they both laughed. “That will teach them,” he said. “They will be blown away while the other ladies will still be here because the wind will not be strong enough to lift…” He stopped once more; Mma Ramotswe was again looking at him expectantly.

The distribution of load, that evidently led to difficulties, but now, as the van started to make an alarming sound again, she realised that this had nothing to do with suspension and traditionally built drivers. This had to do with some fundamental sickness deep in the engine itself; the tiny white van was sick at heart.

She lifted her foot off the accelerator to see if that would help, but all that it did was to reduce the volume of the knocking sound. And when she put her foot down on the pedal again, the noise resumed. Only at a very slow speed, barely above walking pace, did the sound disappear altogether. It was as if the van was saying to her: I am old now; I can still move, but I must move at the pace of a very old van.

She continued her progress down Zebra Drive, steering the van carefully through her gateway with all the care of a nurse wheeling a very sick patient down the corridor of a hospital. Then she parked the van under its habitual tree at the side of the house and climbed out of the driving seat. As she went inside, she debated with herself what to do. She was married to a mechanic, a situation in which any woman would revel, especially when her car broke down. Mechanics made good husbands, as did carpenters and plumbers-that was well known-and any woman proposed to by such a man would do well to accept. But for every advantage that attended any particular man, it always seemed as if there was a compensating disadvantage lurking somewhere. The mechanic as husband could be counted on to get a car going again, but he could just as surely be counted upon to be eager to change the car. Mechanics were very rarely satisfied with what they had, in mechanical terms, that is, and often wanted their customers-or indeed their wives-to change one car for another. If Mma Ramotswe told Mr. J.L.B. Matekoni that the tiny white van was making a strange noise, she knew exactly what he would say, as he had said it all before.