It happened once upon a time that Mullah Nasruddin was doing his daily errands, and after visiting the market, stopped at a tea house. There he fell into conversation with a stranger, who said, “Mullah, you have a turban so you must know the answer. I have heard that the people of your village are unusually intelligent.”

Nasruddin stroked his beard, and said piously, “Allah forbids man to deny what is true.”

“But tell me,” said the stranger, “why should it be so?”

“We consume many olives. There is a special type of olive here and the oil lubricates the brain.”

“Really? Where can I get some?”

“By good fortune,” said Nasruddin, “I happen to have some here. I can sell them to you for three coins.”

The deal was done, and the stranger began at once to eat olives. Then he frowned. “These are the same olives I can get in the market for TWO coins.”

“You see,” said Nasruddin. “They are working already.”