Legend has it that in ancient times, there was a medical expert, a minister of Huangdi, who was skilled in teaching the principles of medicine, diagnosis through inspection of complexion, and the techniques of acupuncture and moxibustion. "Huangdi sat with his nose, summoned Leigong, and asked him: Do you understand the principles of medicine? Leigong replied: I can recite and somewhat comprehend, comprehend but not differentiate, differentiate but not clarify, clarify but not manifest. It is enough to treat the officials." In discussions about acupuncture and moxibustion with Huangdi, they discussed "the principles of all needling," as well as the theory of diagnosing diseases by observing the complexion. From the content of Suwen and Lingshu, it is evident that Leigong was a disciple of Huangdi.