Why did Zhuangzi dream that he had become a butterfly?

Zhuang Zhou had a dream and turned into a butterfly. Lifelike, and enjoy themselves, feel happy and comfortable from the heart, and don't remember Zhuang Zhou at all. I suddenly woke up and realized that I was Zhuang Zhou. I don't know if Zhuang Zhou became a butterfly in his dream or if Zhuang Zhou was in a butterfly dream.

By describing and thinking about a dream scene that many people have in their lives, Zhuang Zhou put forward the view that it is impossible for people to accurately distinguish between reality and illusion and the materialization of life and death.

It is this daily phenomenon that he grasped and put into his works through his own philosophical thinking to prove his argument.