Yin Yang River

During World War II, a Japanese troop with many wound and sick soldiers fled this village and found a medicine doctor in town. Japanese forced the doctor to make  medicine for their soldiers by threatening to kill all village people.
The doctor went up to hill to find plant to prepare for the medicine. He made a pot of medicine soup for the soldiers. But the Japanese wanted village people to drink first. There is no negative sign. Japanese wanted him to duplicate the second pot under supervision.

 

When the medicine soup is ready, Japanese asked him to drink one bowel first right away. The soup is hot, doctor added a little bit water and drink it. After hours, the doctor was fine. Then all the soldiers drank the medicine soup. Later, some Japanese soldiers became sicker and some died. Then all were captured by village people.

 

The trick is the first medicine soup is made of Eastern side Yang Water. The second medicine soup is used the Western soup Yin Water. When the doctor drank the second pot soup, he added some Yang water in to balance the poison.