Let's go to China, over two thousand years ago, to a time called the "Period of the Warring States." Seven kings from seven different states warred fiercely with each other. The weakest state was Han, and the strongest was Chu.
One day, a Han court official purchased a beautiful piece of jade. A jade expert appraised it and declared it the legendary Jade Treasure, a priceless gem with marvelous color and special virtues like shining in the dark and repelling insects.
News traveled fast. The King of Han wanted to see the treasure. Fearing the king would take it, the official considered fleeing. His houseguest, a young man named Gan, advised, "That would not be wise. Offer it to the king outright as a gift." The official did so and was promoted.
Soon, the powerful King of Chu heard of the treasure. "We are the strongest state! We should have it!" he declared. He sent a message to Han, offering 15 cities in exchange. Privately, he told his mandarin, "Once we have the jade, who will remember the 15 cities? What can weak Han do about it?"
The King of Han was worried. Would Chu keep its promise? His new chamberlain suggested seeking Gan's advice. Gan was summoned.
"My king," said Gan, "we must surrender the stone to avoid invasion. Let me be your envoy. Entrust the Jade Treasure to my care. I promise to return it if Chu breaks its word."
To ensure a lucky journey, the Han court fasted for three days, then held a grand send-off feast. With great reverence, Gan wrapped the jade in an embroidered silk pouch and set out with attendants.
In Chu, he was honorably received. When presenting the treasure, the stone gleamed with mesmerizing radiance. The king admired it and passed it around his court. Gan waited, but the jade was not returned, and no one mentioned the 15 cities.
Seeing this, Gan said, "Sire, there is a flaw in the jade. Please let me show you." Once the stone was back in his hands, he stepped near a pillar. "We came in good faith for your offer of 15 cities. If you are acting in good faith, fast for three days and hold a grand ceremony for the exchange. If not, I will smash the jade against this pillar now!"
The King of Chu hastily agreed to the ceremony. For the next three days, he sent a servant each morning to check that Gan still had the jade. Meanwhile, Gan sent a disguised attendant to spy and discovered there was no fast, only a mad scrambling to prepare a hasty ceremony. On the ceremony day, after the king's servant checked on him, Gan secretly sent his most trusted attendant back to Han with the jade.
At the ceremony, Gan announced, "O King, we hesitated because you never discussed the 15 cities. Your state is strong; ours is weak. I had no choice but to send the jade back with my attendant. He is likely halfway home by now."
The court gasped. "This is an outrage!" cried the King of Chu. "You broke the bargain!"
"Kill me if you wish," said Gan. "But only I know my attendant's route. Bring the deeds to the 15 cities, and I will take you to him for a simultaneous exchange. If not, boil me in oil. Let the other states judge you for killing a messenger from the weakest kingdom."
The King of Chu knew killing Gan could inflame other states against him. He also had no deeds prepared, as he never intended to deliver the cities. Thinking quickly, he laughed. "Ah, this was all a test to see how Han handles negotiations! You have performed honorably. Stay for the banquet and return home in peace tomorrow."
Gan returned safely to Han. The King of Han, overjoyed at getting his treasure back, promoted Gan to the highest rank. The King of Han never received the 15 cities, and the King of Chu never received the Jade Treasure.