The source is the secret recipe of Laozi's health preservation, which was constructed by Taoism according to the "knowing the law" in the six-character structure. Looking intently, it is a "secret recipe for health care", originally engraved on a stone tablet in front of the old gentleman in Mingdao Palace, Guxian (now Luyi County, Henan Province). Compared with the words on the stone tablet, the simplified Chinese translation is: burning jade furnace to prolong life, practicing medical skills, practicing longevity pills, breathing in and out, my nature is hollow, and I can forget my fantasy without looking at silent photos. I want to see the natural lead and mercury in my life and hand over the elixir before I can do it.