素问·阴阳离合论 Treatise on the Separation and Union of Yin and Yang
黄帝问曰：余闻天为阳，地为阴，日为阳，月为阴，大小月三百六十日成一岁，人亦应之。今三阴三阳，不应阴阳，其故何也。歧伯对曰：阴阳者，数之可十，推之可百，数之可千，推之可万，万之大不可胜数，然其要一也。天覆地载，万物方生，未出地者，命曰阴处，名曰阴中之阴；则出地者，命曰阴中之阳。阳予之正，阴为之主。故生因春，长因夏，收因秋，藏因冬，失常则天地四塞。阴阳之变，其在人者，亦数之可数。
帝曰：愿闻三阴三阳之离合也。歧伯曰：圣人南面而立，前曰广明，后曰太冲，太冲之地，名曰少阴，少阴之上，名曰太阳，太阳根起于至阴，结于命门，名曰阴中之阳。中身而上，名曰广明，广明之下，名曰太阴，太阴之前，名曰阳明，阳明根起于厉兑，名曰阴中之阳。厥阴之表，名曰少阳，少阳根起于窍阴，名曰阴中之少阳。是故三阳之离合也，太阳为开，阳明为阖，少阳为枢。三经者，不得相失也，搏而勿浮，命曰一阳。
帝曰：愿闻三阴。歧伯曰：外者为阳，内者为阴，然则中为阴，其冲在下，名曰太阴，太阴根起于隐白，名曰阴中之阴。太阴之后，名曰少阴，少阴根起于涌泉，名曰阴中之少阴。少阴之前，名曰厥阴，厥阴根起于大敦，阴之绝阳，名曰阴之绝阴。是故三阴之离合也，太阴为开，厥阴为阖，少阴为枢。三经者，不得相失也。搏而勿沈，名曰一阴。阴阳𩅞𩅞，积传为一周，气里形表而为相成也。
Huangdi asked: I have heard that heaven is yang and earth is yin, the sun is yang and the moon is yin; that the greater and lesser months together make three hundred sixty days forming one year, and that man corresponds to this as well. Now, the three yin and three yang do not seem to correspond simply to yin and yang — what is the reason for this? Qibo replied: Yin and yang can be counted to ten, extended to a hundred, counted to a thousand, extended to ten thousand; and beyond ten thousand they become too great to be counted in full — yet their essential principle is one. Heaven covers and earth supports, and the myriad things are thereby born. That which has not yet emerged from the earth is called dwelling in yin, and is termed yin within yin; that which has emerged from the earth is termed yang within yin. Yang bestows uprightness, and yin serves as its master. Thus birth depends on spring, growth depends on summer, gathering-in depends on autumn, and storage depends on winter; when this normal order is lost, the four directions of heaven and earth become obstructed. The transformations of yin and yang, as they occur in man, can likewise be counted and enumerated.
Huangdi said: I would like to hear about the separation and union of the three yin and three yang. Qibo said: When the sage stands facing south, the front is called Vast Brightness, and the rear is called the Great Thoroughfare. The region of the Great Thoroughfare is called Shaoyin (Lesser Yin); above Shaoyin is called Taiyang (Greater Yang). Taiyang is rooted at the point Zhiyin and knots at the Gate of Life; it is termed yang within yin. Above the midpoint of the body is called Vast Brightness; below Vast Brightness is called Taiyin (Greater Yin); in front of Taiyin is called Yangming (Yang Brightness). Yangming is rooted at the point Lidui, and is termed yang within yin. The exterior aspect of Jueyin (Reverting Yin) is called Shaoyang (Lesser Yang); Shaoyang is rooted at the point Qiaoyin, and is termed the lesser yang within yin. Thus, in the separation and union of the three yang: Taiyang is the opening, Yangming is the closing, and Shaoyang is the pivot. These three channels must not lose their proper relation to one another; when they beat together without floating apart, this is called the unity of yang.
Huangdi said: I would like to hear about the three yin. Qibo said: The exterior is yang, and the interior is yin; thus the interior belongs to yin, and its thoroughfare lies below, called Taiyin (Greater Yin). Taiyin is rooted at the point Yinbai, and is termed yin within yin. Behind Taiyin is called Shaoyin (Lesser Yin); Shaoyin is rooted at the point Yongquan, and is termed the lesser yin within yin. In front of Shaoyin is called Jueyin (Reverting Yin); Jueyin is rooted at the point Dadun — where yin is cut off from yang — and is termed the utmost yin within yin. Thus, in the separation and union of the three yin: Taiyin is the opening, Jueyin is the closing, and Shaoyin is the pivot. These three channels must not lose their proper relation to one another; when they beat together without sinking away, this is called the unity of yin. Yin and yang flow on unceasingly, accumulating and transmitting to complete one full cycle; qi governs the interior, and physical form governs the exterior, and together they bring each other to completion.