There is an emperor or president in the human world, and so there is a Jade Emperor in the supernatural. There is a hierarchy of officials on earth, and so there is a celestial hierarchy of officials in the after-world. And just as people want to maintain harmony in their relations with their fellow men, they also want to maintain harmony in their relations with ghosts and spirits.
人間有皇帝、總統，超自然世界有玉皇；人間有各層官吏，陰間有城隍；人間有種種階級層次，陰間亦有大小不同的神祇，人間要維持種種人際關係的和諧，陰間也要與各種神明維持和諧。