有一次，孔子和他的弟子们一起去参观鲁桓公庙。
在那里，他们看到了一种特别的酒器，叫做“宥卮”。
孔子说：“我终于亲眼看见了‘宥卮’这种酒器！”
于是，他让弟子去拿水来，把水倒进“宥卮”里。
当水灌到一半时，“宥卮”开始倾斜。
但是，当水继续灌满“宥卮”时，它就翻倒了。
看到这一幕，孔子的脸色变了。
他对弟子们说：“这就是‘持盈’的道理。”
子贡请孔子再次解释这个道理。
孔子说：“事物发展到了最高峰，就会开始衰退；欢乐到了极点，就会产生悲哀。就像太阳在正午时开始西落，月亮过了满月就开始缺损。这就是我们常说的物极必反。所以，我们应该追求中庸，适可而止。”
从那以后，“乐极生悲”这个词就用来形容过份的享乐会导致悲哀的结果。
Once, Confucius and his disciples went to visit the Lu Huan Gong Temple together.
There, they saw a special wine vessel called 'You Zhi'.
Confucius said, "I finally see the wine vessel 'You Zhi' with my own eyes!"
So he asked his disciples to fetch water and pour it into the 'You Zhi'.
When the water filled half of the 'You Zhi', it began to tilt.
But when the water continued to fill the 'You Zhi', it overturned.
Seeing this, Confucius's face changed color.
He said to his disciples, "This is the principle of 'holding fullness'."
Zigong asked Confucius to explain the principle again.
Confucius said, "When things develop to their peak, they will begin to decline; when joy reaches its extreme, sorrow will be produced. Just like the sun begins to set at noon, and the moon starts to wane after being full. This is what we often say, 'things turn into their opposites when they reach extremes.' Therefore, we should pursue moderation and stop at the right time."
From then on, the phrase 'joy turns to sorrow' has been used to describe how excessive enjoyment can lead to sad results.
