There was a severe drought in the early years of Chengkang. When the new emperor was at a loss what to do, he burned incense and prayed to heaven according to the instructions of his ancestors. The immortal in the sky was grateful for the kindness of his ancestors and sent two of his disciples to the lower world to help him out of trouble. I don't want the world to be rough and people's hearts to be unpredictable.
Concept: Human nature is changeable, and there is a fine line between good and evil.