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司天在泉四间气者，乃客气之六部也。凡主岁者为司天，位当三之气。司天之下，相对者为
在泉，位当终之气。司天之左，为天之左间，右为天之右间。每岁客气始于司天前二位，乃地之
左间，是为初气，以至二气、三气，而终于在泉之六气，每气各主一步。然司天主行天之气令，
其位在上，自大寒节起，主上半年；在泉主地之气化，其位在下，自大暑节起，主下半年。岁运
居上下之中，主气交之化。故天气欲降，则运必先之而降；地气欲升，则运必先之而升。又论曰∶
初之气、二气、三气尽，天气主之；四气、五气、终气尽，地气主之。此即上下卦之义。然则三
气、四气是一岁之气交也。天地气交之时，自四月终，至八月终，共四个月。一百廿日之间，而
岁之旱潦丰俭，物之生长收成，皆系乎此。故曰∶气交之分，人气从之，万物由之也。
岐伯曰∶上而司天，下而在泉，中而气交，人之居也。言天者求之本，言地者求之位，言人
者求之气交。本者，天之六气，风火暑湿燥寒也。位者，地之六步，
木火土金水火也。言天者求之本，即六气之胜衰，而上可知也。言地者求之位，即六部之终始，
而下可知也。人在天地之中，故求于气交，则安危亦可知矣。又论曰∶天气下降，地气上升，
一升一降，气交于中，人居之则生万物，皆气交之使然。盖天无地之升则不能降，地无天之降
则不能升。天地互相升降，循环之道也。天气不足，地气随之；地气不足，天气从之，运居中
而当先也。如司天生克中运为顺，中运生克司天为逆，在泉亦然。顺分生克之殊，逆有大小之别，
此古人举运气之端倪耳。若其二气相合，象变迥异，变化无穷。如四时有非常之化，常外更有
非常。四时有高下之殊，殊中又分高下。百步内晴雨不同，千里外寒暄非一。故察气候者必因
诸天，察方宜者必因诸地。圆机之士，当因常以察变，因此以察彼。庶得古人未发之妙欤。
罗列如下：
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司天、在泉以及左右四间气，是客气（每年轮转的异常气候）的六个部分。凡是主宰当年岁运的为司天，其位置对应三之气。在司天的下方，与之相对的是在泉，其位置对应终之气。在司天的左侧，称为天之左间气；右侧，称为天之右间气。每年的客气始于司天前两位的位置，即地的左间气，这被称为初气，依次经过二气、三气，最终到达在泉的六气，每一气各主令一个阶段（步）。然而，司天主导体天气令的运行，其位在上，从大寒节气开始，主管上半年；在泉主导地气化运行，其位在下，从大暑节气开始，主管下半年。岁运居于上下之中，主管主气与客气相交的变化。所以，天气想要下降，岁运必须先于天气而下降；地气想要上升，岁运必须先于地气而上升。又有论述说：初气、二气、三气结束时，由天气主导；四气、五气、终气结束时，由地气主导。这就是上下卦的含义。那么三气和四气就是一年中天地之气交接的时候。天地之气交接的时间，从四月末到八月末，共四个月。在这一百二十天之间，一年的旱涝丰歉，万物的生长收成，都取决于此。所以说：在气交之分野，人气顺应它，万物依赖它。
岐伯说：上面是司天，下面是在泉，中间是气交，这是人居住的地方。谈论天的人要探究其根本，谈论地的人要探究其位置，谈论人的人要探究其气交。所谓“本”，是指天的六气，即风、火、暑、湿、燥、寒。所谓“位”，是指地的六步，即木、火、土、金、水、火。谈论天的人探究其根本，就能知道六气的盛衰情况，从而推知上面的变化。谈论地的人探究其位置，就能知道六部的始终，从而推知下面的变化。人处于天地之间，所以探究气交，就能知道安危的情况了。又有论述说：天气下降，地气上升，一升一降，气在中间交汇，人居住在气交之中则能生存并化生万物，这都是气交的作用所致。大概天没有地的上升就不能下降，地没有天的下降就不能上升。天地互相升降，这是循环的规律。如果天气不足，地气就会随之；如果地气不足，天气就会顺从，岁运居于中间且应当先行。比如司天克制中运为顺，中运克制司天为逆，在泉的情况也是如此。顺中有生克的不同，逆有大小之别，这是古人列举运气学说的端倪罢了。如果这两股气相合，象变截然不同，变化无穷无尽。比如四季有非常的气候变化，常规之外更有非常。四季有高下之分，差异之中又分高下。一百步之内晴雨可能不同，千里之外冷暖可能不一。所以观察气候的人必须依据各种天象，观察适宜地域的人必须依据各种地理环境。圆通机敏的人，应当依据常规来观察变化，由此及彼地观察。这样或许能得到古人未曾阐发的奥妙吧。
Listed below:
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Si Tian (Chief Qi of the Year), Zai Quan (Opposing Qi of the Earth), and the four interstitial Qi (Left and Right Intercalary Qi) constitute the six segments of Ke Qi (Annual Transitory Qi). The factor governing the annual cycle is Si Tian, positioned at the Third Qi. Directly opposite and below Si Tian is Zai Quan, positioned at the Final Qi. To the left of Si Tian is the Left Intercalary Qi of Heaven; to the right is the Right Intercalary Qi of Heaven. Each year's Ke Qi begins at the position two steps prior to Si Tian, which corresponds to the Left Intercalary Qi of Earth, designated as the First Qi. It proceeds through the Second and Third Qi, finally reaching the Sixth Qi of Zai Quan. Each Qi governs one segment (Bu). However, Si Tian governs the movement of Heavenly Qi, located above, starting from the Da Han (Great Cold) solar term, presiding over the first half of the year. Zai Quan governs the transformation of Earthly Qi, located below, starting from the Da Shu (Great Heat) solar term, presiding over the second half of the year. The Sui Yun (Annual Movement) resides between heaven and earth, governing the interaction between Zhu Qi (Host Qi) and Ke Qi. Therefore, when Heavenly Qi desires to descend, the Movement must precede it in descending; when Earthly Qi desires to ascend, the Movement must precede it in ascending. Another treatise states: When the First, Second, and Third Qi conclude, they are governed by Heavenly Qi; when the Fourth, Fifth, and Final Qi conclude, they are governed by Earthly Qi. This reflects the meaning of the Upper and Lower Trigrams. Thus, the transition between the Third and Fourth Qi marks the intersection of Qi within a year. The time of Heaven-Earth Qi intersection spans from the end of the fourth month to the end of the eighth month, totaling four months. Within these 120 days, the year's drought or flood, abundance or scarcity, and the growth and harvest of all things depend on this period. Hence it is said: At the point of Qi intersection, human Qi follows it, and all things derive from it.
Qi Bo stated: Above is Si Tian, below is Zai Quan, and in the middle is Qi Jiao (Intersection of Qi); this is where humans reside. Those discussing Heaven seek its Ben (Root/Origin); those discussing Earth seek its Wei (Position); those discussing Humans seek Qi Jiao. "Ben" refers to the Six Qi of Heaven, namely Feng (Wind), Huo (Fire), Shu (Summer Heat), Shi (Dampness), Zao (Dryness), and Han (Cold). "Wei" refers to the Six Steps of Earth, namely Wood, Fire, Earth, Metal, Water, and Fire. Discussing Heaven by seeking its Root allows one to know the excess and deficiency of the Six Qi and infer changes above. Discussing Earth by seeking its Position allows one to know the beginning and end of the Six Segments and infer changes below. Since humans exist between Heaven and Earth, investigating Qi Jiao reveals safety and danger. Another treatise states: Heavenly Qi descends, Earthly Qi ascends; rising and falling, they intersect in the middle. Humans residing in this intersection give birth to all things, all caused by Qi Jiao. Essentially, without Earth's ascent, Heaven cannot descend; without Heaven's descent, Earth cannot ascend. Heaven and Earth mutually ascend and descend, forming a cycle. If Heavenly Qi is insufficient, Earthly Qi follows; if Earthly Qi is insufficient, Heavenly Qi complies. The Movement, situated in the center, acts first. For instance, if Si Tian controls Zhong Yun (Central Movement), it is considered Shun (Smooth/Favorable); if Zhong Yun controls Si Tian, it is Ni (Rebellious/Unfavorable). The same applies to Zai Quan. There are differences in generation and control within Shun, and distinctions in magnitude within Ni. These are merely the rudiments of Yun Qi (Luck and Qi) theory presented by the ancients. If these two Qi combine, their manifestations differ drastically, with infinite variations. For example, the four seasons may exhibit extraordinary transformations beyond the usual. There are high and low distinctions among the seasons, further subdivided. Within a hundred paces, clear and rainy weather may differ; across a thousand li, cold and warm conditions may vary. Therefore, those observing climate must rely on various celestial phenomena, and those assessing regional suitability must rely on various geographical factors. A flexible and astute practitioner should observe change through constancy, and understand one thing through another. In doing so, one might uncover the profound secrets unarticulated by the ancients.