(素问)
子午之岁。上见少阴。丑未之岁。上见太阴。寅申之岁。上见少阳。卯酉之岁。上见阳
明。
辰戌之岁。上见太阳。巳亥之岁。上见厥阴。(此即三阴三阳之应地支也。是为六气上者言
司天。如子午之岁上见少阴司天是也十二年皆然)少阴所谓标也。厥阴所谓终也(标首也终尽
也。六十年阴阳之序始于子午。故少阴谓标尽于巳亥故厥阴谓终)厥阴之上。风气主之。少
阴之上。热气主之。太阴之上。湿气主之。少阳之上。相火主之。阳明之上。燥气主之。
太
少阴湿化太阴。火化少阳燥化阳明寒化太阳。故六气谓本三阴三阳谓标也。然此六者。皆天
元一气之所化。一分为六。故曰六元。)
少阳之上。火气治之。中见厥阴(此以下。言三阴三阳各有表里其气相通。故各有互根
之中
明之上。燥气治之。中见太阴(阳明之本燥。故燥气在上与太阴为表里。故中见太阴是以燥
金而兼湿土之化也)太阳之上。寒气治之。中见少阴(太阳之本寒。故寒气在上。与少阴为表
里。故中见少阴。是以寒水而兼君火之化也)厥阴之上。风气治之中见少阳(厥阴之本风。故
风气在上与少阳为表里故中见少阳是以风木而兼相火之化也)少阴之上。热气治之。中见太
阳(少阴之本热。故热气在上与太阳为表里故中见太阳。是以君火而兼寒水之化也)太阴之上
。湿气治之。中见阳明(太阴之本湿。故湿气在上。与阳明为表里。故中见阳明。是以湿土
而兼燥金之化也)所谓本也。本之下。中之见也。见之下气之标也(此言三阴三阳为六气之标
而兼见于标本之间者是阴阳表里之相合。而互为中见之气也)本标不同。气应异象。
\r上中下本标中气图\pi-i2.bmp\r
六经之气以风寒热湿火燥为本。三阴三阳为标。本标之中见者为中气。中气者。如少阳厥阴为表里。
阳明太阴为表里。太阳少阴为表里。表里相通则彼此互为中气。
百病之起。多生于本。六气之用。则有生于标者。有生于中气者。太阳寒水。本寒标热
。少阴君火本热标寒其治或从本。或从标。审寒热而异施也。少阳相火。从火化为本。太阴湿土
从湿化为本。其治但从火湿之本。不从少阳太阴之标也。阳明燥金。金从燥化。燥为本。阳
明为标厥阴风木。木从风化。风为本厥阴为标。其治不从标本而从乎中中者中见之气也。盖
阳
于中。是以风木从相火之中气为治。亦以二经标本之气不合。故从中见之气以定治耳。
《素问》中提到：子年和午年，司天之气为少阴；丑年和未年，司天之气为太阴；寅年和申年，司天之气为少阳；卯年和酉年，司天之气为阳明；辰年和戌年，司天之气为太阳；巳年和亥年，司天之气为厥阴。（这就是三阴三阳对应地支的情况。这是指六气中位于上方的“司天”之气，例如子午之年，少阴司天，十二年的情况都是如此。）少阴被称为“标”，厥阴被称为“终”（标即开始，终即结束。六十年的阴阳顺序从子午年开始，所以少阴称为始，到巳亥年结束，所以厥阴称为终）。厥阴之上，由风气主令；少阴之上，由热气主令；太阴之上，由湿气主令；少阳之上，由相火主令；阳明之上，由燥气主令；太阳之上，由寒气主令。（注：此处原文有脱漏或错简，根据后文及中医理论，应为“太阳之上，寒气主之”。）少阴湿化，太阴火化，少阳燥化，阳明寒化，太阳……（原文此处似有残缺，通常指太阳寒化，但依下文逻辑推导，此处主要阐述本气与标气的关系）。故六气称为“本”，三阴三阳称为“标”。然而这六种气化，都是由天元一气所化生，一气分为六，所以称为“六元”。
少阳之上，由火气治理，中见厥阴（以下论述的是三阴三阳各有表里关系，其气相通，所以各有互为根本的“中气”。阳明之上，由燥气治理，中见太阴（阳明的本气是燥，所以燥气在上，与太阴构成表里关系，因此中见太阴，这是以燥金兼有湿土的气化特点）。太阳之上，由寒气治理，中见少阴（太阳的本气是寒，所以寒气在上，与少阴构成表里关系，因此中见少阴，这是以寒水兼有君火的气化特点）。厥阴之上，由风气治理，中见少阳（厥阴的本气是风，所以风气在上，与少阳构成表里关系，因此中见少阳，这是以风木兼有相火的气化特点）。少阴之上，由热气治理，中见太阳（少阴的本气是热，所以热气在上，与太阳构成表里关系，因此中见太阳，这是以君火兼有寒水的气化特点）。太阴之上，由湿气治理，中见阳明（太阴的本气是湿，所以湿气在上，与阳明构成表里关系，因此中见阳明，这是以湿土兼有燥金的气化特点）。这就叫作“本”。本的下面，是中见的“中气”；中气的下面，是气的“标”。（这里说的是三阴三阳作为六气的标志，而兼见于标本之间的是阴阳表里的相合，以及互为中见之气。）本和标不同，气化相应的征象也不同。
六经之气以风、寒、热、湿、火、燥为本，三阴三阳为标。在本和标之中见到的称为“中气”。中气，如少阳与厥阴为表里，阳明与太阴为表里，太阳与少阴为表里。表里相通，则彼此互为中气。
各种疾病的产生，多生于本。六气的作用，有的生于标，有的生于中气。太阳寒水，本为寒，标为热；少阴君火，本为热，标为寒。治疗时或者从本论治，或者从标论治，需审察寒热的不同而分别施治。少阳相火，从火化为本；太阴湿土，从湿化为本。治疗时只从火、湿的本气论治，不从少阳、太阴的标气论治。阳明燥金，金从燥化，燥为本，阳明为标；厥阴风木，木从风化，风为本，厥阴为标。它们的治疗不从标本，而是从中气论治。“中”就是中见之气。这是因为阳气居于中，所以风木从相火的中气来论治。也是因为这两经的标本之气不相合，所以依据中见之气来确定治疗方法。
*Suwen* (Plain Questions) states: In the Zi and Wu years, the Si Tian (Heavenly Ruler) Qi is Shaoyin; in the Chou and Wei years, it is Taiyin; in the Yin and Shen years, it is Shaoyang; in the Mao and You years, it is Yangming; in the Chen and Xu years, it is Taiyang; and in the Si and Hai years, it is Jueyin. (This refers to the correspondence between the Three Yin and Three Yang and the Earthly Branches. This describes the Six Qi located above, known as Si Tian [Heavenly Ruler], such as Shaoyin ruling the heavens in Zi and Wu years, a pattern consistent across all twelve years.) Shaoyin is referred to as the Biao (Mark/Manifestation), and Jueyin is referred to as the Zhong (End). (Biao means beginning/start, Zhong means end/conclusion. The sequence of Yin and Yang over sixty years begins with Zi and Wu, hence Shaoyin is called the start; it ends at Si and Hai, hence Jueyin is called the end.) Above Jueyin, Wind Qi governs; above Shaoyin, Heat Qi governs; above Taiyin, Dampness Qi governs; above Shaoyang, Ministerial Fire Qi governs; above Yangming, Dryness Qi governs; above Taiyang, Cold Qi governs. (Note: The original text contains apparent lacunae or transcription errors here; based on subsequent context and TCM theory, it should read "Above Taiyang, Cold Qi governs.") Shaoyin transforms into Dampness, Taiyin transforms into Fire, Shaoyang transforms into Dryness, Yangming transforms into Cold, Taiyang... (The text here seems incomplete, but logically follows to discuss the relationship between Ben [Root] and Biao [Mark]). Thus, the Six Qi are called the Ben (Root), and the Three Yin and Three Yang are called the Biao (Mark). However, these six types of Qi transformation all originate from the One Qi of Tian Yuan (Heavenly Origin). The One Qi divides into six, hence they are called the Liu Yuan (Six Origins).
Above Shaoyang, Fire Qi governs, and the Zhong Qi (Middle Qi) reveals Jueyin. (The following discusses that each of the Three Yin and Three Yang has a Bi-Li [Exterior-Interior] relationship, their Qi connects, and thus each has a mutually rooting Zhong Qi [Middle Qi].) Above Yangming, Dryness Qi governs, and the Zhong Qi reveals Taiyin. (The Ben Qi of Yangming is Dryness, so Dryness Qi is above, forming an Exterior-Interior relationship with Taiyin, therefore the Zhong Qi reveals Taiyin. This represents the transformation of Dryness Metal combined with Dampness Earth.) Above Taiyang, Cold Qi governs, and the Zhong Qi reveals Shaoyin. (The Ben Qi of Taiyang is Cold, so Cold Qi is above, forming an Exterior-Interior relationship with Shaoyin, therefore the Zhong Qi reveals Shaoyin. This represents the transformation of Cold Water combined with Sovereign Fire.) Above Jueyin, Wind Qi governs, and the Zhong Qi reveals Shaoyang. (The Ben Qi of Jueyin is Wind, so Wind Qi is above, forming an Exterior-Interior relationship with Shaoyang, therefore the Zhong Qi reveals Shaoyang. This represents the transformation of Wind Wood combined with Ministerial Fire.) Above Shaoyin, Heat Qi governs, and the Zhong Qi reveals Taiyang. (The Ben Qi of Shaoyin is Heat, so Heat Qi is above, forming an Exterior-Interior relationship with Taiyang, therefore the Zhong Qi reveals Taiyang. This represents the transformation of Sovereign Fire combined with Cold Water.) Above Taiyin, Dampness Qi governs, and the Zhong Qi reveals Yangming. (The Ben Qi of Taiyin is Dampness, so Dampness Qi is above, forming an Exterior-Interior relationship with Yangming, therefore the Zhong Qi reveals Yangming. This represents the transformation of Dampness Earth combined with Dryness Metal.) This is called the Ben (Root). Below the Ben is the revealed Zhong Qi (Middle Qi); below the Zhong Qi is the Biao (Mark) of the Qi. (This explains that the Three Yin and Three Yang serve as the marks of the Six Qi, while what appears between the Ben and Biao is the combination of Yin-Yang Exterior-Interior relationships and the mutually revealing Zhong Qi.) Since the Ben and Biao differ, the corresponding manifestations of Qi also vary.
[Diagram of Upper, Middle, Lower Ben, Biao, and Zhong Qi]
The Qi of the Six Channels regards Wind, Cold, Heat, Dampness, Fire, and Dryness as the Ben (Root), and the Three Yin and Three Yang as the Biao (Mark). What is seen within the Ben and Biao is called the Zhong Qi (Middle Qi). The Zhong Qi implies that Shaoyang and Jueyin form an Exterior-Interior pair, Yangming and Taiyin form an Exterior-Interior pair, and Taiyang and Shaoyin form an Exterior-Interior pair. Because Exterior and Interior are connected, they mutually serve as each other's Zhong Qi.
The onset of various diseases often arises from the Ben. The function of the Six Qi may arise from the Biao or from the Zhong Qi. Taiyang Cold Water has Cold as its Ben and Heat as its Biao; Shaoyin Sovereign Fire has Heat as its Ben and Cold as its Biao. Treatment may follow either the Ben or the Biao, depending on whether Cold or Heat is assessed for differentiated therapy. Shaoyang Ministerial Fire transforms into Fire as its Ben; Taiyin Dampness Earth transforms into Dampness as its Ben. Treatment follows only the Ben of Fire and Dampness, not the Biao of Shaoyang or Taiyin. Yangming Dryness Metal transforms into Dryness as its Ben, with Yangming as its Biao; Jueyin Wind Wood transforms into Wind as its Ben, with Jueyin as its Biao. Their treatment does not follow the Ben or Biao but rather the Zhong Qi (Middle Qi). "Zhong" refers to the Qi of the Zhong Jian (Middle Manifestation). This is because Yang Qi resides in the middle, so Wind Wood is treated according to the Zhong Qi of Ministerial Fire. Furthermore, since the Ben and Biao Qi of these two channels do not align, treatment is determined by the Zhong Qi.