A person in a city state called QI worried about the collapse of the sky.He got so worried that he could not sleep and eat well.Another person who worried about the first person gave him an explanation.He said,"The sky is a bunch of air.There is air everywhere,just moving around all the time.How can it collapse?" The first person said," If so,how come the sun,the moon and the stars do not fall?".The other person answered,"The sun,the moon and the stars are the air with brightness.Eevn if they fall,they won't hurt." The first person asked again:"How about the earth?" The other person answered:"The earth is filled with soil.You stand and walk on it all the time.How can that be destroyed?"
So,the first person relieved with joy and so did the second person.