John and Sam were friends. They opened a small shop in a small village. One day, they sold out of all their wine (酒), so they drove to the city to buy some.
On their way home, the wind was strong and it was getting colder and colder. Both John and Sam wanted to drink some wine to keep warm, but they had a rule. They couldn't drink any wine because they had to sell it. Because of the rule, if someone wanted to drink some wine, he had to pay the other twice the price.
John was a clever man. He took out ten cents and gave it to Sam. He said, "Here is ten cents. Would you please sell me some of your wine?" Sam was a businessman (商人), so he said, "You give me money, so of course I will sell some to you." Then he passed John a cup of wine.
After drinking the wine, John felt warm soon, but Sam was still cold. Then he took out the ten cents that John just gave to him and said to John, "Here is ten cents. Please sell me some of your wine." John agreed. Sam drank some wine and also felt much warmer. But after some time, they both felt cold again, so they kept buying wine from each other with the same ten cents. Soon they drank up all of the wine.
"How could so much wine only cost ten cents?" the two friends asked each other.