Says Kung Peng-cheng: "The later you go in history, the more people tried to create specific images out of abstract concepts in order to explain the idea that people became spirits or ghosts after death.
「越到後來，人們為了說明死後成神變鬼的道理，要把抽象觀念具象化，天堂才被構築起來」，龔鵬程以為。