黄帝问曰∶卫气之在于身也，上下往来不以期，候气而刺之，奈何？伯高曰∶分有多少
，日有长短，春秋冬夏，各有分理，然后常以平旦为纪，以夜尽为始。是故一日一夜水下百
刻，二十五刻者，半日之度也，常如是无已。日入而止，随日之长短，各以为纪而刺之，谨
候其时，病可与期。失时反候者，百病不治。故曰∶刺实者，刺其来也；刺虚者，刺其去也
。此言气存亡之时，以候虚实而刺之。是故谨候气之所在而刺之，是谓逢时。病在于三阳，
必候其气在于阳而刺之；病在于三阴，必候其气在阴分而刺之。
水下一刻人气在太阳；水下二刻，气在少阳；水下三刻，气在阳明；水下四刻，气在阴
分；水下五刻，气在太阳；水下六刻，气在少阳；水下七刻，气在阳明；水下八刻，气在阴
分；水下九刻，气在太阳；水下十刻，气在少阳；水下十一刻，气在阳明；水下十二刻，气
在阴分；水下十三刻，气在太阳；水下十四刻，气在少阳；水下十五刻，气在阳明；水下十
六刻，气在阴分；水下十七刻，气在太阳；水下十八刻，气在少阳；水下十九刻，气在阳明
；水下二十刻，气在阴分。水下二十一刻，气在太阳；水下二十二刻，气在少阳；水下二十
三刻，气在阳明；水下二十四刻，气在阴分；水下二十五刻，气在太阳，此半日之度也。从
房至毕一十四舍，水下五十刻，日行半度，回行一舍，水下三刻与七分刻之四。大要
曰∶常以日之加于宿上也，人气在太阳。是故日行一舍，人气行三阳，行与阴分，常如是无
已，天与地同纪，纷纷HT HT 终而复始，一日一夜，水下百刻而尽矣。
The Yellow Emperor asked: The Wei Qi (Defensive Qi) moves up and down in the body without a fixed schedule. How should one observe its movement to perform acupuncture? Bo Gao replied: The divisions of the body vary, and the lengths of day and night differ across the seasons of Spring, Autumn, Winter, and Summer, each having its own principles. Therefore, we usually take Pingdan (dawn) as the standard reference point, starting when the night ends. Thus, in one full day and night, water drips for one hundred ke (ancient time units). Twenty-five ke represents half a day's cycle, which continues endlessly. Acupuncture is stopped at sunset. Following the varying lengths of days, we establish specific timing standards for needling. By carefully observing the appropriate time, the disease can be cured. Missing the time or violating the patterns means that various diseases cannot be treated. It is said: For excess conditions, needle when the Qi arrives; for deficiency conditions, needle when the Qi departs. This refers to observing the timing of the Qi's presence or absence to determine deficiency or excess before needling. Therefore, carefully observing where the Qi is located and needling accordingly is called "meeting the time." If the disease is in the Three Yang meridians, one must wait until the Qi is in the Yang aspect to needle; if the disease is in the Three Yin meridians, one must wait until the Qi is in the Yin aspect to needle.
At the first ke after water dripping begins, the Ren Qi (Vital Qi) is in the Taiyang (Greater Yang) meridian; at the second ke, it is in Shaoyang (Lesser Yang); at the third ke, it is in Yangming (Yang Brightness); at the fourth ke, it is in the Yin division; at the fifth ke, it returns to Taiyang; at the sixth ke, Shaoyang; at the seventh ke, Yangming; at the eighth ke, Yin division; at the ninth ke, Taiyang; at the tenth ke, Shaoyang; at the eleventh ke, Yangming; at the twelfth ke, Yin division; at the thirteenth ke, Taiyang; at the fourteenth ke, Shaoyang; at the fifteenth ke, Yangming; at the sixteenth ke, Yin division; at the seventeenth ke, Taiyang; at the eighteenth ke, Shaoyang; at the nineteenth ke, Yangming; at the twentieth ke, Yin division. At the twenty-first ke, it is in Taiyang; at the twenty-second ke, Shaoyang; at the twenty-third ke, Yangming; at the twenty-fourth ke, Yin division; at the twenty-fifth ke, it is in Taiyang, marking the end of half a day. From the Fang mansion to the Bi mansion covers fourteen mansions. During this period, fifty ke pass, and the Sun travels half the celestial sphere. For every mansion the Sun retreats, three ke plus three-quarters of a ke pass. The general principle states: When the Sun aligns with a specific mansion, the Ren Qi is in the Taiyang meridian. Thus, as the Sun moves through one mansion, the Ren Qi circulates through the Three Yang meridians and the Yin divisions, continuing endlessly. Heaven and Earth follow the same laws, complex and cyclical, ending only when one hundred ke have passed in a full day and night.