The merchant had borrowed money from the moneylender to equip his trading venture. The merchant's ship had not returned on time, and it was presumed lost. The moneylender came to demand payment of the debt. The merchant was pleading for more time. The moneylender was insisting on immediate payment; otherwise, he would have the merchant thrown into the debtor's prison. They were arguing the point in the merchant's garden.

 

At this point the moneylender noticed the merchant's beautiful daughter. He told the merchant that in exchange for the daughter's hand in marriage, the debt would be cancelled. The merchant rejected the offer.

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"You do not have much choice," replied the moneylender, "but I am a fair man. I am going to pick up two stones from this path on which we are standing, a black stone and a white stone. I shall put both stones into this leather bag. Your daughter will put in her hand and bring forth one of the stones­ without looking. If she picks the white stone, the debt is cancelled, and your daughter stays with you. If she picks the black stone, your daughter agrees to marry me, and the debt is cancelled. In all other cases, you pay the debt or go to debtor's prison."

 

Seeing that they would be no worse off and might even have a chance of escape, the daughter suggested they agree to the terms. She then watched the moneylender carefully and noted that he put two black stones into the bag. What was she to do? She could expose the moneylender as a cheat. She could take a black stone and then accept her fate or refuse to marry the fellow anyway. It was at this point that she used some lateral thinking.

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She put her hand into the bag and drew out one of the stones. Then she immediately fumbled and dropped the stone onto the path.  Once the stone had come to rest on the path, there was no way of telling which of the many stones on the path had been the one in the bag.

 

"Oh, I am so sorry," said the girl.

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"It was a black stone you picked," said the moneylender.

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"Nonsense," said the merchant. "There was not enough time to see the stone." "Then we must start over again," replied the moneylender.

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"That will not be necessary," suggested the girl. "All we have to do is to open the bag and see the colour of the stone that remains behind. In that way we can surely tell the colour of the stone that was taken by me." She took the bag and handed it to her father.

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The merchant opened the bag so that all could see the contents. At the bottom of the bag rested a black stone.

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"See," exclaimed the girl, "a black stone remains in the bag. So, I must surely have taken the white one."

 

The debt was cancelled. The girl remained with her father, and almost everyone was happy.

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This is the story with which I opened my first book Lateral Thinking which was published in 1967. This story illustrates so well the nature of "lateral thinking."

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In hindsight the girl's action is both logical and effective - but few people in the same situation would have thought of it.

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