Tradition has it that many,many years ago,there lived on the Yellow River a river god known as He Bo.One day ,He Bo stood on the riverbank and watched the turbulent waves from the west surging forward to the east.He said both excitedly and conceitedly:"How big the Yellow River is !No other river on earth can compare with it.And therefore I am the greatest river god."
One man said to him,"You are wrong.There is a place to the east of the Yellow Rivers called the North Sea.The North Sea is really big."He Bo said,"I don't believe it .Big as the North Sea is, can it be bigger than Yellow River?"The man said,"Should the water of several Yellow River flow into the North sea,it could not fill the North Sea,let alone one Yellow River. "
He Bo said obstinately,"I don't believe it,for I have never been to the North Sea."
Having no alternative,the man said,"You will not be able to" understand what I mean until you have a chance to see the North Sea for yourself."
Winter came,and torrential rain had been falling for days on end.Rivers big and small emptied themselves into the Yellow River,making the Yellow River even broader.Standing on one side of the river,people could hardly tell what animals the oxen and horses on the other side of the river were.Thus He Bo was even more proud,thinking that all the magnificent sights were accumulated here.Then ,remembering the North Sea which had been mentioned to him before,he decided to go there and have a look.
He went downstream,and arrived at the river mouth to the sea.Suddenly,the god of the North Sea,whose name was Biennia Ruo,appeared before his eyes.With a smile,Beihai Ruo was welcoming He Bo to the North sea.He looked ahead,and saw that the North Sea,with its vast expanse of water,was boundless.With a dull look in his eyes,He Bo stood there for a while.Finally he said to Beihai Ruo with deep feeling,"As the common saying goes,some people go so far as to think that they are more knowledgeable than anybody else when they have got some knowledge.Actually I am one of such people.If I had not seen with that the Yellow River is matchless in the world.If I remained like that, I would be laughed at for ever by sensible people."
During the Spring and Autumn Period (707 - 476 B.C.), Duke Xian of the State of Jin Wanted to expand his position of strength and sphere of influence. Therefore he would like to send his troops to destroy the State of Guo on the pretest that the State of Guo often encroached on theborders of the State of Jin. But there was a third state, the State of Yu,between the State of Jin and the State of Guo, and the Jin army had to cross the State of Yu before it could reach the State of Guo . "How can my army cross the State of Yu without a hitch?" Duke Xian of the State of Jin asked his ministers.Xun Xi , one of the ministers, said, "The monarch of the State of Yu is short - sighted and covets small advantages. If we give him priceless precious stones and fine horses, it is not unlikely that he will allow our army to pass through his country. " Seeing that Duke Xian of the State of Jin was a little bit grudging, Xun Xi continued to say, "The State of Yu and the State of Guo are neighbor stated as closely related as lips and teeth. The State of Yu cannot exist independently if the state of Guo is destroyed. Your precious stones and fime hores are just left in the care of the monarch of the State of Yu." So Duke Xian of the State of Jin accepted Xun Xi's plan. When the monarch of Yu saw the precious gifts, he was elated,and readily promised to let the Jin army pass through his state. Hearing the news, Gong Zhiqi, one of the ministers as the State of Yu, hastened to admonish the monarch, saying," That won't do.For the State of Yu and the State of Guo are neighbor states as closely related as lips and teeth. Our two small states are interdependent, and can help cach other when problems crop up .If the State of Guo were destroyed, it would be difficult for our State of Yu to continue to exist. As the common saying goes, if the lips are gone ,the teeth will be cold, The teeth can hardly be kept if the lips are gone. So it won't do at all to allow the Jin army pass our state." The monarch of the State of Yu said," The State of Jin is a big state. Now they here specially to present gifts to us with the intention of being on friendly terms with us. Under suchcircumstances, how can we refuse to allow them to pass through our state?" Hearing this, Gong Zhiqi sighed repeatedly. Knowing that the State of Yu would soon be destroyed, Gong Zhiqi left the State of Yu together with his whole family.
As expected, the troops of the State of Jin, allowed to pass through the State of Yu, destroyed the State of Guo and on their return trip captured the monarch of the State of Yu who went out personally to meet them, htus destroying the State of Yu as Well.
This story appears in the chapter " The Fifth Year of Duke Xi " in Zuo zhuan,the famous commentary by Zuo Qiuming on The Spring and Autumn Annals. The set phrase " if the lips are gone, the teeth will be cold " is used to mean that two persons or things share a common lot and that is one fails ,the other is in danger.