Jean was out walking with his grandfather in Paris.

At one point, they saw a shoemaker being insulted by a customer who claimed that there was something wrong with his shoes.

The shoemaker calmly listened to his complaints, apologised and promised to make good the mistake.

Jean and his grandfather stopped to have a coffee.

At the next table, the waiter asked a man if he would mind moving his chair slightly so that he could get by.

The man erupted in a torrent of abuse and refused to move.

‘Never forget what you have seen,’ said Jean’s grandfather.

‘The shoemaker accepted the customer’s complaint, while this man next to us did not want to move.

‘People who perform some useful task are not bothered if they hear some critics to their work, but people who do no useful work at all always think themselves very important and hide their incompetence behind their authority.’