師曰：清靜之道，人能辨之，則盡善盡美矣。故經云：人能常清淨，天地悉皆歸。言天地者，非外指覆載之天地也，蓋指身中之天地也。人之膈已上為天，膈已下為地。若天氣降，地脈通，上下沖和，精氣自固矣。此小任仙所說也。
Our Teacher Ma Danyang said:
The Path of Clear Stillness, if people have discernment, is completely good and beautiful. So the Classic says If a person can be always clear and quiet, Heaven and Earth will revert completely.
Here, the meaning of ‘Heaven’ and ‘Earth’ is not the heaven covering us, or the earth supporting us, but the Heaven and Earth within us, in our body. Above the diaphragm is ‘Heaven’, below the diaphragm is ‘Earth.’ If Heavenly qi can descend, the channels of Earth will open, and above and below will course together harmoniously. In this way, vitality and qi will become consolidated by themselves. Anyway, this is how Xiao Ren Xian explains it.
The “Classic” mentioned is the Qing Jing Jing (清靜經).
Who exactly Xiao Ren Xian (小任仙) might be is so far unknown.
The Fat Monk 