Mma Makutsi stared intently at Mma Ramotswe, the light flashing off her large round spectacles. It was as if she were challenging her employer to contradict a fundamental scientific truth. Mma Ramotswe said nothing at first; she was at this time discovering that Mma Makutsi in full flight was not to be interrupted lightly. But when no further assertions came, she very gently ventured a question as to where Mma Makutsi had learned to discern character in this way.

‘Life experience,’ said Mma Makutsi. ‘There are some things you cannot learn from books. You cannot be taught instinct.’

Mma Ramotswe absorbed this. ‘But surely you must be careful, Mma. People cannot help the way they look. A person who is good inside may look bad outside. I am sure there are many cases of that.’

Mma Makutsi’s glasses flashed a danger signal. ‘Really, Mma? Name one, please. Name one person who looks bad outside but who is good inside.’ She paused, before adding, ‘I am waiting.’

Mma Ramotswe looked up at the ceiling. She was sure that there were such people, but she found it difficult to bring anybody to mind. ‘Violet Sephotho?’ she suggested. ‘What about her? She looks all right on the outside but is definitely bad on the inside.’

Mma Makutsi let out a hoot of laughter. ‘Violet Sephotho, Mma? You say that she looks good on the outside? She does not, Mma! She does not! That woman looks on the outside exactly as she is on the inside. And that, I must say, is bad, very bad.’

Mma Ramotswe was kind. Surely even Violet Sephotho, for all her manifest faults, had her better moments. ‘I’m not sure that she looks bad absolutely one hundred per cent of the time, Mma,’ she said. She had almost said ninety-seven per cent of the time, but managed to stop herself. ‘I have seen her smiling sometimes.’

This was as a red rag to Mma Makutsi. ‘Smiling, Mma? A smile is the most dangerous disguise of all. Many people smile to disguise what they are thinking inside.’