Why does the light of the lightning come before the thunder?
Leigong is the God of Thunder in Chinese Mythology. He produces thunder with his drum and mallet and punishes both earthly mortals guilty of secret crimes and evil spirits who have used their knowledge of Taoism to harm human beings.
He punishes the evildoers by the order of the Jade Emperor who is one of the most important gods in Chinese Mythology. But whenever he strikes someone, the sky gets very dark, he cannot see can’t see, and sometimes kills the wrong person.
In one of these dark days, Leigong again loses his target and accidentally kills a woman named Dianmu. The Jade Emperor learns the wrong strike of Leigong and gets very angry. He revived Dianmu and makes her into the Goddess of Lightning.
He says to Leigong, “Killing Dianmu was your fault, and from now on Dianmu is your responsibility. Marry her, she is your wife.” He gives Leigong his pounds. Leigong mumbles “I hope she is beautiful at least” (The last two sentences are purely my imagination).
Beautiful or not, Leigong marries Dianmu and no longer makes any mistakes in punishing the earthlings. Dianmu each time uses mirrors to shine light onto earth and since it is no longer dark, Leigong can see who he hits and makes sure they aren’t innocent.
That’s why they say the light of the lightning comes before the thunder.