It happened once upon a time that two merchants met at an oasis in the middle of a wide desert. One was from a land by the sea and carried with him a collection of pearls of different sizes and grades, while the other was from a mountainous land, and brought with him a supply of gems of varying quality.. Although they did not speak the same language, each one had the instinct for trade, and they soon began to inspect each other’s merchandise.
The man with the pearls saw value in the jewels of the other, and the gem merchant saw value in the pearls. By gestures, it was the work of only a few moments to agree to exchange the one stock for the other – so that the pearl merchant received the stones, and the gem seller received the pearls. However, the gem merchant was quick with his hands, and managed to conceal the best stone of his collection in his sleeve.
That night, the seller of pearls slept well, contented that he had made a good profit. The other merchant, though, slept badly, tormented by the thought that the pearl merchant must also have hidden his best piece, and wondering how much he had lost as a result.