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.”