These NeiDan practices are based on the text “Ancestor Qiu’s Secret Transmission of the Direct Guide to the Great Elixir”
It is claimed the text to be a direct transmission of the “Ming gong” or of the Northern School of Internal Alchemy and was brought to the Daoist Scholar Chen Yingning in the 1930s by a priest from Shandong who was seeking to verify its authenticity.
Chen affirmed that this method was the inner door, secret transmission of the Northern School. Most Northen school practices focus on the development of the original nature and the energetic practices were closely guarded.
The text is written in relatively modern Chinese. This does not mean that the text is not an authentic northern school text, but it, like many, is most likely the accumulation of hundreds of years of experience since the teachings of Qui Chiji the sage they attribute this document to.