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."
相传很久很久以前，黄河里有一位河神，人们叫他河伯。何伯站在黄河岸上。望着滚滚的浪涛由西而来，又奔腾跳跃向东流去，兴奋地说；“黄河真大呀，世上没有哪条河能和它相比。我就是最大的水神啊！”
有人告诉他：“你的话不对，在黄河的东面有个地方叫北海，那才真叫大呢。”
河伯说：“我不信，北海再大，能大得过黄河吗？”
那人说：“别说一条黄河，就是几条黄河的水流进北海，也装不满它。”
河伯固执地说：“我没见过北海，我不信。”
那人无可奈何，告诉他：“有机会你去看看北海，就明白我的话了。”
秋天到了，连日的暴雨使大大小小的河流都注入黄河，黄河的河面更加宽阔了，隔河望去，对岸的牛马都分不清。这一下，河伯更得意了，以为天下最壮观的景色都在自己这里，他在自得之余，想起了有人跟他提起的北海，于是决定去那里看看。
河伯顺流来到黄河的入海口，，突然眼前一亮，海神北海若正笑容满面地欢迎他的到来，河伯放眼望去，只见北海汪洋一片，无边无涯，他呆呆地看了一会儿，深有感触地对北海若说：“俗话说，只懂得一些道理就以为谁都比不上自己，这话说的就是我呀。今天要不是我亲眼见到这浩瀚无边的北海，我还会以为黄河是天下无比的呢！那样，岂不被有见识的人永远笑主。”
故事见于《庄子·秋水》。成语“望洋兴叹”，比喻要做某事而力量不够，感到无可奈何。