During the reign of Emperor Cheng of the Western Han Dynasty, legend has it that Liu Xiang was diligently proofreading books in the Tianlu Pavilion.

One night, an old man, dressed in yellow and leaning on a staff made of qingli wood, entered.

Seeing Liu Xiang studying alone in the dark, the old man blew on his qingli staff, which then illuminated the room, and proceeded to teach him the "Five Elements and Grand Plan" (Wuxing Hongfan).

Fearing he might forget, Liu Xiang tore strips from his clothing and meticulously jotted down every word.

By the break of dawn, the elder, an essence of Taiyi, departed.