乐极生悲

Chunyu Kun lived in the state of Qi during the Warring States Period (475-221 BC). He was wise, humorous and eloquent（雄辩的）. He skillfully advised the king on many occasions and successfully went to many states as an envoy.

In the year 349 BC, the State of Chu dispatched a large force to attack Qi. The king of Qi sent Chunyu Kun to the state of Zhao to ask for help, with a lot of valuable gifts. The king of Zhao accpeted the gifts gladly and sent a hundred thousand troops to help Qi. The king of Chu withdrew his army that very night as soon as he got the news.

The king of Qi was released and pleased with Chunyu Kun. He set a banquet（盛宴） for celebration. During the meal, the king asked Chunyu Kun, "How much wine can you drink before you're drunk, Sir?" Knowing the king had a bad habit of drinking all night, Chunyu Kun decided to take this chance to admonish（告诫） the king. So he replied, "I get drunk when I drink ten litres or hundred."

Puzzled, the king asked, "Since you are drunk after ten litres, how can you finish another ninty litres?"

Chunyu Kun then explained that he could drink different amounts of wine under different conditions. He said, "This occurs to me that when you drink to your limit, you get so drunk that you lose your sense; once joy reaches its height, then it's sorrow's turn. This is the rule for everything. Whatever you do, you are bound to end up in the opposite direction when you exceed the limits."

Realizing Chunyu Kun was advising him, the king answered, "You are right. I will take your advice."

From then on, the king of Qi gave up his bad habit of drinking and playing all night.