真源曰∶天地之间，亲乎上者为阳，自下而上四万二千里，乃曰阳位。亲乎下者为阴，自上而下四万二千里，乃
曰阴位。既有形名，难逃度数，且一岁者，四时八节，二十四气，七十二候，三百六十日，四千三百二十辰，十二
辰为一日，五日为一候。三候为一气，三气为一节，二节为一时，四时为一岁，一岁以冬至节为始，是时也。地中阳
生升，凡一气十五日，上升七千里，三气为一节，四十五日，阳升共二万一千里，二节为一时，一时九十日，阳升
共四万二千里，正到天地之中，而阳合阴位，是时阴中阳半，其气为温，而时当春分之节也。过此阳升而入阳位，方
曰得气而升，亦如前四十五日立夏，立夏之后，四十五日夏至，夏至之节，阳升通前计八万四千里，以到天。
乃阳中有阳，其气热，积阳生阴，一阴生于二阳之中，自夏至之节为始，是时天中阴降，凡一气十五日，下降七千
里，三气为一节，一节四十五日，阴降共二万一千里，二节为一时，一时九十日，阴降共四万二千里，正到天地之
中，而阴交阳位，是时阳中阴半，其气为凉，而时当秋分之节也。过此阴降而入阴位，方曰得气而降，亦如前四十五日
立冬，立冬之后，四十五日冬至，冬至之节，降极通前计八万四千里，以到地，乃阴中有阴，其气冷，积阴生阳，一阳
生于二阴之中，自冬至之后，一阳升如前，营运不已，周而复始，即阳升阴降之八节，而知天地，即温凉寒热之四气，
而识阴阳，夫阴阳判分，若黑白然。故春夏秋冬四时，随令各别，温热凉寒四时，随节候变易，冬至已后至春分属伤寒，
自春分至夏至属温病，自夏至至白露属伤暑，自白露至立冬属凉病，自立冬以后至春俱属伤寒，盖春秋之气尝不足，冬
夏之气尝有余，即四月八月间亦有暑病，盖八月间晓暮夜气虽凉而午未之时，秋阳燥烈，日火灼人，反毒于伏，盖伏
时气发汗出，阳气在表，此时阳气渐敛，真火内燃，而又以烈日熏之，故毒易中人，热证更剧，当细察之，虽其
外证相类，而受气不同，治法迥异，稍有不中节，害人不浅。而概用以寒证剂，其害可胜言哉！治者先数时令，后
审时气，随令加减斟酌之，未有不立取效者，故为天时说。
霖按∶论四时阴阳升降，即十二辟卦六阴充足于十月亥，阴极则阳生，故十一月冬至，一阳生于下，为地雷
复卦，二阳生为地泽临，三阳生为地天泰，四阳生为雷天大壮，五阳生为泽天央，至四月六阳充足，则为乾卦。阳极
阴生，故五月夏至一阴生于下，为天风 卦，二阴生为天山遁，三阴生为天地否，四阴生为风地观，五阴生为山地
剥，至十月六阴纯静，则为坤卦。夫坤为万物之母，坤静而纯阴，何能生物？必待干与之交，得其阳而后始能生万
物也。然交必阳体充足，干之六阳乃充足于四月之巳，次为午，干至五月夏至，阳气升极，则下交感，坤阴之气上承，
故一阴动于下，为天风 也。再交于六月未，三交于七月申，所谓坤三索于干也。干阳潜藏于坤阴，至冬至一阳
动于下，故为地雷复也。此阴阳消长之机，不可移易者也。然既明阴阳升降消长之理，辟叔和序例，寒毒藏于肌
肤，春变为温，夏变为暑是矣。然不得界划时日，为温热凉寒，未免缘木求鱼。夫治病之法，首当察其微甚，辨其阴
阳，触类旁通，则头头是道。冬至阳生，井泉温，人身所伏者阳热，被冬日严寒所折，藏于肌骨之间，或为外邪逗引，
或
为情欲所伤，感而触发，伏气至浅，感寒至重，则为伤寒。伏气日久较重，至春感风热而发者，则为春温。伏
气至重，延至立夏后，夏至前，为情欲所伤而发者，则为热病。然微甚之机，又不必泥执立夏前为温，夏至前为热，
惟当以伏气之轻重以分温热也。若夫夏至阴生，井泉寒，人身所伏者阴湿，伏气微感天日之阳，热重者阴邪易
消，惟余热炽，自当以辛寒泄热，伏气重，所感之阳邪微，宜用苦温以燥湿。设表里两重，又当消息香薷饮以加减矣。
活法运乎一心，固不可囿于方圆之中，亦不可出于规矩以外，天时人事，其庶几乎。
叶真源说：天地之间，亲近上方的属于阳，从下往上四万二千里，称为阳位。亲近下方的属于阴，从上往下四万二千里，称为阴位。既然有了形体和名称，就难以逃脱度数的规律。一年包含四季、八个节气、二十四个气节、七十二候、三百六十天、四千三百二十个时辰（十二个时辰为一天），五天为一候。三候为一个气节，三个气节为一个季节，两个季节为一个时季（季度），四个时季为一年。一年以冬至节气为开始，此时地中的阳气开始上升。每经过一个气节（十五日），阳气上升七千里；三个气节为一个季节（四十五日），阳气共上升二万一千里；两个季节为一个时季（九十日），阳气共上升四万二千里，正好到达天地之中，此时阳气与阴位相合，阴中有一半是阳，其气候表现为温暖，对应春分节气。过了这个节点，阳气上升进入阳位，才称为得到气机而继续上升，就像前文所述的四十五日后立夏，立夏之后四十五日是夏至。到了夏至节气，阳气累计上升八万四千里，到达天顶。此时阳中有阳，气候炎热，积存的阳气产生阴气，一阴生于二阳之中。从夏至节气开始，天上的阴气开始下降。每经过一个气节（十五日），阴气下降七千里；三个气节为一个季节（四十五日），阴气共下降二万一千里；两个季节为一个时季（九十日），阴气共下降四万二千里，正好到达天地之中，此时阴气与阳位相交，阳中有一半是阴，其气候表现为凉爽，对应秋分节气。过了这个节点，阴气下降进入阴位，才称为得到气机而继续下降，就像前文所述的四十五日后立冬，立冬之后四十五日是冬至。到了冬至节气，阴气累计下降八万四千里，到达地底。此时阴中有阴，气候寒冷，积存的阴气产生阳气，一阳生于二阴之中。自冬至之后，一阳上升如同之前一样，运行不停，周而复始。通过这阴阳升降的八个关键节气，就可以了解天地变化；通过温、凉、寒、热四种气候，就可以认识阴阳。阴阳分开，就像黑和白一样分明。因此春夏秋冬四季，随着时令各有不同；温热凉寒四种气候，随着节气变化而更替。从冬至后到春分属于伤寒范畴，从春分到夏至属于温病范畴，从夏至到白露属于伤暑范畴，从白露到立冬属于凉病范畴，自立冬以后到次年春季都属于伤寒范畴。大概春秋两季的气候往往不足，冬夏两季的气候往往有余。即使在四月和八月之间也会有暑病，因为八月间早晚夜气虽然凉爽，但中午未时，秋日的太阳燥烈，烈日灼人，其毒性反而比伏暑时节更甚。盖因伏暑时节人体发汗出，阳气在体表，此时阳气逐渐收敛，真火在内燃烧，再加上烈日的熏蒸，所以毒邪容易侵入人体，热证更加剧烈，应当仔细考察。虽然外表症状相似，但受邪之气不同，治疗方法截然不同，稍微不合节度，对人的伤害就不浅。如果一概用治疗寒证的方剂，其危害怎能说得完呢！治病的人先要推算时令，然后审察当时气候，根据时令加减斟酌用药，没有不立刻见效的，所以撰写了这篇关于天时的论述。
霖按语：论述四季阴阳的升降，即十二辟卦中六阴在十月亥月充足，阴极则阳生，所以十一月冬至时，一阳生于下方，对应地雷复卦；二阳生对应地泽临卦；三阳生对应地天泰卦；四阳生对应雷天大壮卦；五阳生对应泽天夬卦；到四月六阳充足，则为乾卦。阳极则阴生，所以五月夏至时，一阴生于下方，对应天风姤卦；二阴生对应天山遁卦；三阴生对应天地否卦；四阴生对应风地观卦；五阴生对应山地剥卦；到十月六阴纯静，则为坤卦。坤代表万物之母，坤性静且纯阴，怎么能生育万物？必须等待乾与之交合，得到阳气后才能生育万物。然而交合必须阳气体势充足，乾的六阳在四月巳月充足，其次是午月，乾至五月夏至，阳气升至极点，则向下交感，坤阴之气向上承接，所以一阴动于下方，形成天风姤卦。再交合于六月未月，三交合于七月申月，这就是所谓坤向乾索取三次（指生成三女）。乾阳潜藏于坤阴中，至冬至时一阳动于下方，所以形成地雷复卦。这是阴阳消长的机理，不可改变。既然明白了阴阳升降消长的道理，驳斥王叔和《序例》中“寒毒藏于肌肤，春天变为温病，夏天变为暑病”的说法是正确的。然而如果不划分清楚时日界限来区分温热凉寒，未免缘木求鱼。治病的方法，首要观察病情的轻重，辨别阴阳，触类旁通，就能条理清晰。冬至阳气初生，井水变温，人体所潜伏的是阳热，被冬日严寒所折服，藏在肌骨之间，或者被外邪逗引，或者被情欲所伤，感应而触发。若伏气较浅，感受寒邪较重，则为伤寒。若伏气日久且较重，到春天感受风热而发作，则为春温。若伏气极重，延续到立夏后、夏至前，被情欲所伤而发作，则为热病。然而轻重的机理，不必拘泥于立夏前为温病，夏至前为热病，只应当根据伏气的轻重来区分温热。至于夏至阴气初生，井水变寒，人体所潜伏的是阴湿。若伏气轻微，感受天日之阳，热重者阴邪易消，只有余热炽盛，自然应当用辛寒药泄热；若伏气重，所感的阳邪微，宜用苦温药燥湿。如果表里同病，又应当斟酌香薷饮进行加减。活法在于一心灵活运用，固然不能局限于方圆之中，也不能超出规矩之外，天时与人事，大概就是这样吧。
Ye Zhenyuan said: Among heaven and earth, that which is close to the upper part belongs to Yang. From below upwards for forty-two thousand li, it is called the Yang position (Yang Wei). That which is close to the lower part belongs to Yin. From above downwards for forty-two thousand li, it is called the Yin position (Yin Wei). Since there are forms and names, one cannot escape the laws of measurement. A year consists of four seasons, eight solar terms, twenty-four Jieqi (solar terms), seventy-two Hou (five-day periods), three hundred and sixty days, and four thousand three hundred and twenty Chen (two-hour periods). Twelve Chen make one day; five days make one Hou. Three Hou make one Jieqi; three Jieqi make one season (Jie); two seasons make one Shi (quarter-year); four Shi make one year. The year begins with the Winter Solstice (Dongzhi) solar term. At this time, Yang Qi within the earth begins to rise. For every Jieqi (fifteen days), Yang Qi rises seven thousand li. Three Jieqi constitute a season (forty-five days), during which Yang Qi rises a total of twenty-one thousand li. Two seasons constitute a Shi (ninety days), during which Yang Qi rises a total of forty-two thousand li, reaching exactly the middle of heaven and earth. At this point, Yang merges with the Yin position. Yin contains half Yang, and its climate is warm, corresponding to the Spring Equinox (Chunfen) solar term. Beyond this, Yang rises into the Yang position, only then is it said to obtain Qi and continue rising. This is similar to the description before: forty-five days after the Beginning of Summer (Lixia), and forty-five days after Lixia is the Summer Solstice (Xiazhi). By the Summer Solstice solar term, Yang Qi has cumulatively risen eighty-four thousand li, reaching the top of heaven. Here, Yang contains Yang, and the climate is hot. Accumulated Yang generates Yin; one Yin is born from within two Yangs. Starting from the Summer Solstice solar term, Yin Qi in heaven begins to descend. For every Jieqi (fifteen days), Yin Qi descends seven thousand li. Three Jieqi constitute a season (forty-five days), during which Yin Qi descends a total of twenty-one thousand li. Two seasons constitute a Shi (ninety days), during which Yin Qi descends a total of forty-two thousand li, reaching exactly the middle of heaven and earth. At this point, Yin intersects with the Yang position. Yang contains half Yin, and its climate is cool, corresponding to the Autumn Equinox (Qiufen) solar term. Beyond this, Yin descends into the Yin position, only then is it said to obtain Qi and continue descending. This is similar to the description before: forty-five days after the Beginning of Winter (Lidong), and forty-five days after Lidong is the Winter Solstice (Dongzhi). By the Winter Solstice solar term, Yin Qi has cumulatively descended eighty-four thousand li, reaching the earth. Here, Yin contains Yin, and the climate is cold. Accumulated Yin generates Yang; one Yang is born from within two Yins. After the Winter Solstice, one Yang rises as before, operating ceaselessly, cycling round and round. Through these eight key solar terms of Yang rising and Yin descending, one can understand heaven and earth; through the four climates of Warmth, Coolness, Cold, and Heat, one can recognize Yin and Yang. Yin and Yang separate, just like black and white. Therefore, the four seasons of Spring, Summer, Autumn, and Winter differ according to their respective times. The four climates of Warm, Hot, Cool, and Cold change according to the solar terms. From after Winter Solstice to Spring Equinox belongs to the category of Shanghan (Cold Damage); from Spring Equinox to Summer Solstice belongs to the category of Wenbing (Warm Disease); from Summer Solstice to White Dew (Bailu) belongs to the category of Shangshu (Heat Stroke/Summerheat Injury); from White Dew to Beginning of Winter belongs to the category of Liangbing (Cool Disease); from after Beginning of Winter until the following spring all belong to the category of Shanghan. Generally, the Qi of Spring and Autumn is often insufficient, while the Qi of Winter and Summer is often excessive. Even between April and August, there may be Shubing (Summerheat diseases). This is because although the night air in August is cool at dawn and dusk, at noon and Wei hour (1-3 PM), the autumn sun is dry and fierce, scorching people, and its toxicity is actually worse than that of the Fushu (latent summerheat) period. During the Fushu period, the body sweats, and Yang Qi is on the exterior. At this time, Yang Qi gradually converges, and the True Fire burns internally. Furthermore, subjected to the scorching sun, the toxin easily invades the human body, making the heat syndrome more severe. One must examine this carefully. Although the external symptoms are similar, the pathogenic Qi received is different, and the treatment methods are completely different. If slightly off the mark, the harm to people will be profound. If one generally uses formulas for cold syndromes, how could the harm be described! Those who treat diseases must first calculate the seasonal timing, then examine the seasonal Qi, and adjust medications according to the season. There will be no case where immediate efficacy is not achieved. Thus, this discourse on heavenly timing was written.
Lin commented: Discussing the rising and falling of Yin and Yang in the four seasons refers to the twelve Pi Gua (opening trigrams). In the tenth month (Hai month), six Yin lines are full. When Yin reaches its extreme, Yang is born. Hence, at the Winter Solstice in the eleventh month, one Yang is born below, corresponding to the Di Lei Fu Hexagram (Earth over Thunder). Two Yangs born correspond to Di Ze Lin (Earth over Lake). Three Yangs born correspond to Di Tian Tai (Earth over Heaven). Four Yangs born correspond to Lei Tian Da Zhuang (Thunder over Heaven). Five Yangs born correspond to Ze Tian Guai (Lake over Heaven). By the fourth month, when six Yang lines are full, it becomes the Qian Hexagram (Heaven). When Yang reaches its extreme, Yin is born. Hence, at the Summer Solstice in the fifth month, one Yin is born below, corresponding to the Tian Feng Gou Hexagram (Heaven over Wind). Two Yins born correspond to Tian Shan Dun (Heaven over Mountain). Three Yins born correspond to Tian Di Pi (Heaven over Earth). Four Yins born correspond to Feng Di Guan (Wind over Earth). Five Yins born correspond to Shan Di Bo (Mountain over Earth). By the tenth month, when six Yin lines are purely quiet, it becomes the Kun Hexagram (Earth). Kun represents the mother of all things. Kun is still and purely Yin; how can it generate things? It must wait for interaction with Qian, obtaining Yang before it can generate all things. However, interaction requires sufficient Yang substance. The six Yangs of Qian are fully present in the Si month of the fourth month, followed by the Wu month. When Qian reaches the Summer Solstice in the fifth month, Yang Qi rises to its peak, then descends to interact. The Qi of Kun Yin ascends to receive it, so one Yin moves below, forming the Tian Feng Gou Hexagram. Interaction continues in the Wei month of the sixth month, and for the third time in the Shen month of the seventh month. This is what is meant by Kun seeking three times from Qian. Qian Yang hides within Kun Yin. At the Winter Solstice, one Yang moves below, thus forming the Di Lei Fu Hexagram. This is the mechanism of Yin-Yang waxing and waning, which cannot be altered. Having clarified the principles of Yin-Yang rising, falling, waxing, and waning, Wang Shuhe's Preface stating "cold toxin hides in the skin and muscles, transforming into Warmth in Spring and Summerheat in Summer" is correct. However, without clearly demarcating time periods to distinguish Warmth, Heat, Coolness, and Cold, one would be climbing a tree to catch fish. The method of treating disease primarily involves observing the severity, distinguishing Yin and Yang, and applying knowledge analogously, thereby achieving clarity in every aspect. At Winter Solstice, Yang is born, and well springs become warm. What lies latent in the human body is Yang-Heat. Subdued by the severe cold of winter, it hides between the muscles and bones. It may be triggered by external pathogens or injured by desires/emotions. If the latent Qi is shallow and the cold felt is heavy, it results in Shanghan (Cold Damage). If the latent Qi is long-standing and heavier, and erupts in spring due to wind-heat, it results in Chunwen (Spring Warmth). If the latent Qi is extremely heavy, extending past Beginning of Summer but before Summer Solstice, and erupts due to injury by desires, it results in Rebing (Heat Disease). However, the mechanism of lightness and heaviness should not be rigidly bound to defining pre-Lixia as Warmth and pre-Xiazhi as Heat. One should only distinguish Warmth and Heat based on the severity of the latent Qi. Regarding Summer Solstice, Yin is born, and well springs become cold. What lies latent in the human body is Yin-Dampness. If the latent Qi is slight and feels the Yang of heaven and sun, if heat is heavy, Yin evil is easily消散 (dissipated); only if residual heat is blazing should one use Pungent-Cold herbs to drain heat. If latent Qi is heavy and the felt Yang evil is slight, one should use Bitter-Warm herbs to dry dampness. If both exterior and interior are involved, one should consider adjusting Xiangru Yin (Mosla Decoction) accordingly. Living methods operate through the mind; one must not be confined within squares and circles, nor should one go outside the compass and square. Heavenly timing and human affairs, perhaps they are thus.