One night the emperor journeyed in a dream to the Moon Palace, where he came into possession of a most peculiar book. He brought it back to the court, but none of the civilian or military officials there could decipher it. Suddenly Lei Haiqing spoke the first words of his life: "It's a musical score."
後來被唐明皇召入皇宮擔任樂官，有一天唐明皇夢遊月宮，得到一部奇書，滿朝文武皆無法破解，這時候雷海青卻突然開口說話：「此工尺譜也」。