Beat The Grass To Startle The Snake
When you cannot detect the opponent's plans launch a direct, but brief, attack and observe your opponent reactions. His behavior will reveal his strategy.
Song Dynasty China
One day, in the county of Jian-zhou, there was a man who lost a precious object. The local magistrate Chen Shu-ku, was called in to investigate. He questioned several people, but no one could tell him who the thief was. So Magistrate Chen laid a trap for those he suspected. "I know of a temple," he told them, "whose bell has great spiritual power that can tell a thief from an honest man. Since my investigation is at a standstill we must employ the supernatural powers of the bell to solve the matter." The magistrate had the bell brought to the courthouse and displayed in the rear chamber. Then he had the suspects brought in to testify to their guilt or innocence. He explained to them that if an innocent man touched the bell it would remain silent, but, if a guilty man touched the bell it would ring out. After lighting incense and chanting prayers, the magistrate had curtains erected around the bell. Previously he had instructed one of his assistants to secretly smear ink on the bell after the curtains were closed. Each suspect was then told to place his hand through the curtain and touch the bell. As they withdrew their hands Chen would examine them. Everyone's hands were stained except those of one man, who confessed to the theft. He did not touch the bell for fear it would ring.