Here's a story I stumbled across: There was a child who often went to play under a big tree when he was very young, and the big tree often said to him, let's play happily together, and every time the child agreed. One day, the child grew up and was no longer the child who only knew how to play, but the big tree still said to him, let's all play together, the child said: No, I don't want to play now, I want to can you give me a toy? The big tree said, I don't have toys...