In the past, a man in the State of Qi was plagued by wild flights of fancy all day long. He feared that the sky might collapse, the land might cave in, and he would have no place to live. His worry was so great that he could neither eat nor sleep.
A concerned man came to enlighten him, saying: "The sky is merely a mass of air. All human activity occurs within it. Why worry about it falling?"
The man from Qi asked: "If the sky is truly an air mass, wouldn't the sun, moon, and stars fall down?"
The man replied: "The sun, moon, and stars are merely luminous objects within this mass. Even if they fell, they would not harm people."
The man from Qi asked again: "Then what should I do if the land sinks?"
The man said: "The land is simply piled-up earth. Earth is everywhere. You walk upon it every day. Why worry that it might sink?"
Upon hearing this, the man from Qi's worries vanished instantly, and he became very glad. The man who had enlightened him and cured his melancholy was also very pleased.