A farmer owed a large debt to an ugly old man that would result in debtor's prison if not repaid. With a bad harvest, the farmer could not pay. The old man proposed marrying the farmer's daughter to cancel the debt. She was given the choice to pick a pebble from a bag - black meant marriage, white meant freedom but debt remains. However, when she picked she dropped it, mixing with the road pebbles. Realizing the second pebble would determine the first, she revealed both pebbles were black, outsmarting the old man and freeing her father without sacrificing herself. The story illustrates using lateral thinking to solve problems that traditional logic cannot.