Circular Dynamics of Ancient Chinese Medicine III

by Peng Ziyi (1871-1949)

Translated from the Original Chinese by Bryan McMahon

Explanation of the Circular Dynamic of the 24 Solar Terms

The “summer heat” of the two solar terms of Xiǎoshǔ Lesser Heat and Dàshǔ Greater Heat refers to the heat of the sun that strikes the surface of the earth. The sun is the source of all life. This heat descends into the earth during autumn, sinks deeper and is stored during winter by combining with the water element, reemerges to the surface of the earth in spring, and expands upward into the atmosphere in summer. The cycle begins anew with the onset of autumn as newly arrived heat descends into the water element within the earth. The strength of metal is the ability to descend heat.

The two solar terms of Lìqiū Beginning of Autumnand Chúshǔ End of Heat are the beginning point of the annual cycle of circular dynamics. At the Beginning of Autumn, the great expanse of earth is in close proximity to the sky; pressure begins to descend.  During the End of Heat, this pressure continues to build forcing any heat at the surface that has not yet entered into the earth to be absorbed. The character 处 chúmeans “to return” or “to enter”. It describes the process by which the heat at the surface is returned below ground by way of the descending action of autumn metal. This correlates to the period of 中伏 zhōngfú, the middle fuperiod of the hottest portion of the year. The third gēng day following the summer solstice marks the beginning of 初伏 chūfú, or initial fú period; the fourth gēng day marks the beginning of 中伏 zhōngfú, ormiddle fu period; the fifth gēng day marks the beginning of the 末伏 mòfú, orfinal fú period. 伏 fú refers to the descending energy of metal and how it drives this heat down into the earth. Although the surface is hot prior to the initial fú period, you don’t get the feeling of this fragrant heat wafting up into the nose; this feeling appears during the initial fú period. During the middle fú period, this fragrant heat wafting up from the earth’s surface becomes more pronounced. The final fú period roughly coincides with the End of Heat; once the End of Heat has passed, there is a clear shift and the surface of the earth feels cool, owing to the fact that a large portion of the summer heat has already been absorbed. The descending energy of gēng metal is the atmospheric pressure of the great qi. Please refer to the Life and the Universe chapter for further discussion on qi phenomena. 

The character 杀 shā used to describe the“withering and killing” of autumn energy is synonymous with the character 降 jiàng, to descend. People often interpret it to mean “death”, referring to the return of yang qi in autumn from the branches of a plant to its roots as in the proverb “falling leaves return to their roots”. These two definitions are in fact describing the same thing; the ten thousand things return to their roots as yang qi descends during the period following the Beginning of Autumn and the End of Heat. As a result, the human body should feel strong and vital during this period. 

During the two solar terms of Báilù White Dew and Qiūfēn Autumn Equinox, heat has descended, giving birth to the fluids as dew now appears on the ground in morning and evening. Prior to the Autumn Equinox, the heat above ground is greater than that below. As summer heat continues to descend into the earth and dew emerges, the amount of heat above ground and below reaches an even balance. This is the meaning of the name 秋分 qiūfēn, or “dividing of autumn”. 

During the two solar terms of寒露 Hánlù Cold Dew and 霜降 Shuāngjiàng Descent of Frost, the amount of heat below the surface of the earth is now greater than that above. The atmospheric pressure pushing downward into the earth is also stronger and so cold now manifests at the surface. The dew of Cold Dew progresses from a cool sensation to one of cold. Half a month later, even more heat has entered into the earth as the gathering power of the great qi further increases in strength. Cold energy increases and dew gives rise to frost. This feeling is particularly clear within the earthen cave homes of the peoples of the northwest. In the houses of the southeast region, a warmth can also be felt inside despite generally cooler weather at this time of year. This is due to the warmth that is stored within the earth. The same is true of the human body; the warmth in the lower half of the body should increase at this time. 

During its annual cycle, it is said that the great qi descends in autumn, is stored in winter, rises in spring and expands in summer. This gives the impression that it is the great qi that actually descends, is stored, rises, and expands when in fact it is the yang heat of the period of Greater and Lesser Heat that is moving through this cycle. 

During 立冬 Lìdōng Beginning of Winter, the yang heat that has descended begins to sink. If the yang heat of Greater and Lesser Heat fails to descend and sink, either partially or completely, there will be no yang qi to rise and expand the following spring and summer. The grain crops will fail to seed; the human body will suffer diseases of deficient cold. As yang heat descends below ground and is stored within water, the surface shifts from cool to cold and the interior shifts from warm to hot. Cold means that gathering power is strong as rain gives rise to the snows of 小雪 Xiǎoxuě Lesser Snow. This is why mine workers need to wear warmer clothing in summer but may work naked in winter. It is cooler in summer and warmer in winter within the interior of the earth. 

During 大学 DàxuěGreater Snow, the downward sinking action of yang heat intensifies as the snows above ground grow stronger. The deeper the snow is at the surface, the deeper the yang heat has sunk below. Circular dynamics dictate that when the descending action of a given energy system has reached its apex, yang heat will begin to rise. 冬至 Dōngzhì Winter Solstice is this period of transition from descending to rising. If at this point the weather is warm, or there is thunder, or fog appears, this indicates that yang qi is leaking out. This heat above and cold below produces deadly forms of warm disease that peak during the spring and summer months of the coming year. At Winter Solstice, the yang qi of nature and of the human body is strongly concentrated in the lower. Abundant yang leads to movement and so it is common to suffer symptoms of nocturnal emission and leukorrhea. 

During the two solar terms of 小寒 Xiǎohán and 大寒 Dāhán, the transition from descending to rising creates direct up and down movement that cannot produce material form. The rising and descending of the great qi of organic life is circular. The original nature of yang heat is movement, rising directly upward; this is a natural fact. Lesser and Greater Cold follow the Winter Solstice in the annual progression. Cold is the ability to seal and store. Yang heat that has undergone this storage by cold can no longer act according to its nature and rise directly. Lesser and Greater Cold are periods of deep sealing and storing. This yang heat that sinks into the water below the surface is the foundation for the arising of all life. If during the period following Winter Solstice, cold stores sufficiently and the foundation is strong, there will be ample generation and growth. If it is especially cold during the period following Winter Solstice, the harvest the following year will be abundant with no danger of widespread disease. Even in places that do not get cold enough for frost or snow in winter, sufficient winter cold is essential to limiting disease. When the yang heat that is stored within the water below emerges to the surface, it manifests as thunder or fog. Yang qi should be sealed and stored during the winter; these signs indicate it is leaking out, that the root is being pulled up. This is why in a place like Chongqing where the fog is heavy in winter, it is appropriate to use Fuzi for many patients in order to tonify the yang. 

Following the cold of winter, the warmth of spring energy begins to grow. This warmth is none other than the yang heat that was stored during winter within the water below the surface that now begins to reemerge. Fire emerges from water; its qi is warm and harmonious. With 立春 Lìchūn Beginning of Spring, the yang heat of the great qi shifts from sinking to rising. Yang heat descends in winter and dew gives rise to frost as the surface cools. With雨水YǔshuǐRain Waters, yang heat rises and rains give rise to abundant water as the surface warms. The root of yang qi is stimulated during this period, leading to many deficient conditions in young children. 

During winter, yang heat is gathered and stored within the water below ground; the ten thousand things follow this yang heat in sinking and so the insects go into hibernation. With the full onset of spring and 惊蛰JīngzhēWaking of Insects, the birds and beasts pair off to mate, snakes and insects wake from hibernation and the grasses and trees begin to sprout; the ten thousand things are roused into action by the reemergence of stored yang qi. 春分 Chūnfēn Spring Equinoxis easily understood in contrast with秋分 Qiūfēn Autumn Equinox. Prior to Autumn Equinox, the yang heat above ground is greater than that below; after, the yang heat below ground is greater than that above. Prior to Spring Equinox, the yang heat below ground is greater than that above; after, the yang heat above ground is greater than that below. Because of the reduced presence of yang heat below, most seasonal conditions that arise after Spring Equinox are the result of deficiency in the lower [burner]. 

As yang heat first rises above ground and begins to expand, the surface is dark. 清明 QīngmíngClear Brightness follows Spring Equinox, giving way to great clarity and brightness as yang qi continues to rise up into the atmosphere. Abundant rising yang heat above the surface leads to plentiful rains, making 谷雨 Gǔyǔ Grain Rains the ideal time for planting. With greater yang heat rising above ground, the root of yang qi below grows weak. This leads to externally contracted conditions and fevers that often grow worse if treated with cooling herbs. 

Summer begins as the yang heat that was sealed and stored below ground transitions from rising to expanding during 立夏 Lìxià Beginning of Summer. 满 mǎn or “fullness” refers to the fullness of yang heat now above ground. This next period of 小满 Xiǎomǎn Lesser Fullness is a comparison to Greater Heat. At this time, the yang heat at the surface is moderately full, not only from the stored yang qi of the previous year that is emerging but also now as the sun shifts from the south to the north, the yang heat that the surface receives also contributes to this fullness. But still, the root of yang qi for all organic life remains primarily the stored yang heat from the previous year. With abundant yang heat above, the yang heat below ground is very deficient. This leads to widespread seasonal conditions of cold below from Lesser Fullness onward.

During 芒種 Mángzhǒng Ripening of the Grains, the grain crops reach their fullest following the abundant heat and rain of Lesser Fullness and Grain Rains. 夏至 Xiàzhì Summer Solstice represents another extreme. Winter Solstice is the time when yang heat reaches its apex of descending and so begins to rise; Summer Solstice is the time when yang heat reaches its apex of rising and so begins to descend. Lesser Heat and Greater Heat follow Summer Solstice through to Beginning of Autumn; Lesser Snow and Greater Snow follow Winter Solstice through to Beginning of Spring. In Beginning of Spring, yang rises; in Beginning of Autumn yang descends. The initial descension of yang that begins with Summer Solstice must first pass through Lesser and Greater Heat before it truly descends; the initial rising of yang that begins with Winter Solstice must pass through Lesser and Greater Snow before it truly rises. The greater the degree of rising and descending, the stronger this circular dynamic will generate middle qi. This is why places with very hot summers and very cold winters tend to produce very intelligent people. Yang rises following the transitional period from Winter Solstice to Beginning of Spring, but the descension of yang begins with the initial and middle fu periods prior to Beginning of Autumn. The largest obstacle to this cycle of generation is the failure of yang qi to descend. The innate nature of yang is to rise; it is difficult to preserve this descension of yang. This is why the Neijingdescribes deficiency as yang qi exiting [the body] and excess as yang qi entering [the body]. When yang qi rises, it exits; when yang qi descends, it enters. This is why people feel lethargic during spring and summer months and robust in the autumn and winter months. 

To summarize, the 24 solar terms are based on the heat of the sun that reaches the surface of the earth in summer, descends below ground in autumn, is stored within water during winter, rises out of storage in spring, expands upward into the atmosphere in summer and begins again with the descension of summer’s heat. One complete cycle of rising and descending gives birth to middle qi. The taiji at the center of the diagram represents the presence of middle qi, the life of the ten thousand things. 

Autumn gathers, winter stores; autumn descends, winter sinks. Spring births, summer grows; spring rises, summer expands. Rising means the rising of yang heat; expansion means the expansion of yang heat; descending means the descending of yang heat; sinking means the sinking of yang heat; storing means the storing of yang heat; gathering means the gathering of yang heat; growing means the growing of yang heat; birthing means the birthing of yang heat. 

Living in the northern temperate zone of the earth, at Summer Solstice I observe the sun move south, the atmospheric pressure begin to bear down and the sun’s heat descend below the surface. At Winter Solstice, I observe the sun move north and the atmospheric pressure that had been driving energy below ground into the water, begin to lift, continuing through to the onset of summer forming the 24 solar terms with spring warmth, summer heat, autumn cool and winter cold. This is the meaning of the great nature of the universe, that which is “constant”. There are the 卯 mǎo, 午 wǔ, 酉 yǒu, 子 zǐ periods of the day just as there are the spring, summer, autumn and winter seasons of the year. Shanghan Lun patterns of Stomach and Large Intestine heat grow worse during the 申shēn and 酉 yǒu periods; nocturnal emission and leukorrhea occur at night; spring brings warm disease and summer cholera while the body thrives in autumn and winter. These are all manifestations of the dynamic movements of the great qi. Therefore, to study Chinese medicine, you must first become familiar with the great qi and its 24 solar terms. 

This diagram must be read as a whole. When reading the rising of yang, you must also consider its state of descension; when reading the descending of yang, you must also consider its state of rising. When reading the state of energy above ground, you must also consider the state of energy below ground; when reading the state of energy below ground, you must also consider the state of energy above ground. When reading spring, you must also consider autumn; when reading winter, you must also consider summer. When reading descending on the right and rising on the left, you must also consider the middle. Overlaying this diagram of rising on the right and descending on the left over the body, you can begin to recognize the wonder of the human body as a microcosm of the movements of a single qi and the subtle art of treating disease. 

The character 節 jié in 節氣 jiéqì refers to the nodes in bamboo. The space between the nodes is smooth, with some difficulty crossing over at the points of intersection. There is also stagnation in the great qi as it transitions through the nodes. It is a time when many patients suffering from chronic disease and poor circulation in the interstitial spaces die. Those whose complexion improves with the approach of a node transition often improve once that transition is completed. This is another reflection of Chinese medicine as the study of the microcosm of the human body. It shows the importance of diligent study of the 24 solar terms beyond any confusion. Confirmation must be sought through the careful observation of reality as it manifests in the bodies of our patients. I often say that sitting at home reading medical books is nowhere near as effective a way to learn medicine as being in a hospital interacting with patients day in and day out the way nurses are. But there are no hospitals for Chinese medicine, so all we can do is read our empty books. And if the books we read are of poor quality, progress is all the more difficult. This diagram of the 24 solar terms is the “hospital” of Chinese medicine.