One day, ChouRyo (Zhang Liang) failed to assassinate ShiKotei (Shi Huangdiand) and hid himself under the bridge.
The old man riding a house dropped his shoes from the bridge.
He asked ChouRyo to pick it up and he did for the old man.
The old man appreciated him and asked to meet here again in the morning after 5 days later as you’ll be given something variable.
Five days later, the old man came earlier than ChouRyo and said why you came so late and kept me waiting.  The old man ordered to come here again in the early morning after 5 days after. ChouRyo came here before sun rising and then the old man came to see ChouRyo. 
The old man said that modesty is important and gave him the military tactics and told that if you would read it you’ll be a strategist of the king after 10 years. After studying it and then ChouRyo became a capable strategist.