5. What is Danchun?
  
   There are three Danchuns; one is the upper Danchun, another is the middle Danchun, and the last is the lower Danchun. The upper Danchun lies midway between the eyebrows approximately three inches inside the skull. The middle Danchun is in the middle of the body between the nipples about two or three inches inside the chest. The lower Danchun is located about two inches below the navel and approximately one third of the way in, but the exact location varies depending on a person's weight and structure. It hangs on the two kidneys midway between Paekhoe and Yongchun.
  Assuming the human body is the union of heaven, earth, and man, the head corresponds to heaven, the legs to earth, and the trunk to man. In the trunk the heart, which corresponds to heaven, conducts 'fire' and the kidneys, which corresponds to earth, conduct 'water'. 'Heaven (yang) force' and 'earth (yin) force' are integrated in the lower Danchun.