The saying that humans and ghosts belong to different worlds has its own particular meaning in Daoism.
Humans live by their vital energy and blood, giving rise to feng shui manifestations that circulate fortune. Ghosts endure through their souls, stealing people's fortune, vital energy, and blood essence to nourish themselves.
The power of the great masters of ancient times was originally the spiritual fortune of Heaven and Earth. But once the art of feng shui emerged, so did the evil path of stealing other people's fortune...
