《黄帝内经·灵枢·岁露论》
卫气出离风府穴，每天沿脊椎下行一节，到第二十一日，下行到尾骶骨，然后在第二十二日，又向上移入于脊内，流注于伏冲脉，再循脉上行九日，上出于左右两缺盆穴的中间，在这段时间内，卫气是逐日升高，因此发病的时间，就一天早于一天。
卫气之行风府，日下一节，二十一日下至尾底，二十二日入脊内，注于伏冲之脉，其行九日，出于缺盆之中，其气上行，故其病稍益至。
Defensive qi moves out of the Wind Mansion acupoint, descends one node along the spine each day, reaches the coccyx on the twenty-first day, and then moves back into the spine on the twenty-second day, flows into the Fu Chong Channel, and then rises along the channel for nine days, exits from the middle of the left and right Quepen acupoints, during which time, defensive qi rises day by day, so the time of onset is one day earlier than the previous day.