Xiu Dan Dao can practice those Dan.

The so-called elixir of life refined by Taoism. Jin Gehong's "Bao Puzi Jin Dan": "Nine-day service to Dan." In the Southern Dynasties, Liang Jiangyan's poem "Giving an alchemy method and a long history of Yin Dynasty" said: "Yan Fang's" The magical device ",the golden algae alchemy." Yin Mingtang's poem "Poems on Paintings": "What is hidden in the waist? Lotus nine turns to one Dan. "