As stated in Lingshu (Spiritual Pivot), in the chapter Xieke: “Human beings correspond with Heaven and Earth”. In the classical literature of traditional Chinese medicine (TCM), the term Tian (Heaven) collectively denotes the natural environment including the seasons, climate, and the cycle of day and night. TCM recognises that changes in this natural environment affect the human body. Therefore, whether in health preservation or the treatment of disease, one must consider the impact of environmental changes on the body.

In Suwen (Plain Questions), chapter Shengqi Tongtian Lun (Treatise on Generating Qi and Communication with Heaven), it is stated: “When the qi of Heaven is clear and pure, the will and intention are regulated. By following it, yang qi is secured; even if pathogenic factors invade, they cannot cause harm. This accords with the seasonal sequence.” If the natural order operates normally and without disorder, the spirit is thereby regulated. By conforming to the natural order, yang qi is secured and consolidated, thereby strengthening resistance to pathogenic factors.

But how, then, does one accord with the natural order?

In Lingshu (Spiritual Pivot), chapter Shunqi Yiri Fenwei Sishi (Dividing the Day into the Four Seasons According to the Flow of Qi), it is written: “Spring gives rise, summer promotes growth, autumn gathers, and winter stores: this is the constant pattern of qi. Human beings should also respond accordingly. A single day may likewise be divided into four seasons: morning corresponds to spring, midday to summer, sunset to autumn, and midnight to winter.” This passage indicates that within the annual cycle, yang qi rises and engenders in spring, flourishes in summer, converges in autumn, and is stored in winter. The human body is influenced by these seasonal transformations and should respond accordingly. The same principle applies within a single day: in the morning, as the sun rises and yang qi begins to ascend, activity should commence; at midday, when yang qi is at its height, activity may be most vigorous; at dusk, as yang qi withdraws, activity should gradually diminish; at midnight, corresponding to winter, the body should rest and store, allowing yang qi to be conserved.

Furthermore, in Lingshu (Spiritual Pivot), chapter Benshen (Root of the Spirit), it is stated: “Therefore, in practising health preservation, the wise must follow the four seasons and adapt to cold and heat.”

Accordingly, all aspects of daily life, including the regulation of rising and retiring, clothing appropriate to climatic conditions, dietary choices, the degree of physical activity, and the regulation of mental activity, as well as the selection of treatment methods, formulas and medicinals in TCM, should be adjusted in accordance with the four seasons, both within the yearly cycle and within the daily cycle. In Suwen, chapter Siqi Tiaoshen Dalun (Great Treatise on Regulating the Spirit in Accordance with the Four Qi) provides a detailed exposition of this principle.