  Traditionally, the Heshanggong commentary is regarded as a product of the early Han dynasty. The name Heshanggong means an old man who dwells by the side of a river, and some have identified the river in question to be the Yellow River. An expert on the Laozi, he caught the attention of Emperor Wen, who went personally to consult him. Heshanggong revealed to the emperor his true identity as a divine emissary sent by the “Supreme Lord of the Dao”—i.e., the divine Laozi—to teach him. The emperor proved a humble student, as the legend concludes, worthy of receiving the Daodejing with Heshanggong’s commentary (A. Chan 1991).