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In spring, the pulse is string-like (Xian); in summer, it is surging (Hong), which should be described as hook-like (Gou); in autumn, it is feathery (Mao); in winter, it is stone-like (Shi); and throughout the four seasons, a gentle and moderate quality characterizes the Ping Mai (Normal Pulse).

An excessive, solid, and strong pulse indicates disease originating from the exterior. An deficient, weak, and minute pulse indicates disease originating from the interior.

If the feathery pulse of autumn appears in spring, death will occur on a Metal day. The same logic applies to the five Zang organs; deduction based on this principle will not fail.

The root of all diseases occurring in the four seasons lies in the Wei Qi (Stomach Qi). The pulse must possess Shen (Spirit/Vitality); this must be carefully examined.

The Qi of Heaven and Earth rises eastward, belonging to Wood, corresponding to the Yin and Mao positions, and the season of Spring, when all things begin to grow. This Qi emerges from a state of dormancy, like a wisp of smoke or a thread of spring water. In the human body, the Liver corresponds to this, manifesting as a Xian (String-like) pulse. This is what is referred to in the *Su Wen: Yu Ji Zhen Zang Lun* (Treatise on the True Viscera from the Jade Machine) as "its Qi arrives soft, weak, light, void, smooth, straight, and long"; and in the *Su Wen: Ping Ren Qi Xiang Lun* (Treatise on the Phenomena of the Normal Person's Qi) as "soft and swaying, like holding the tip of a long bamboo pole."

The Qi turns southward, belonging to Fire. It corresponds to the Si and Wu positions, and the season of Summer, when all things flourish and grow. This Qi ascends and then disperses outwardly, like surging waves or a prairie fire. In the human body, the Heart corresponds to this, manifesting as a Gou (Hook-like/Surging) pulse. This is what the *Yu Ji Zhen Zang Lun* describes as "its Qi arrives abundant and departs declining," and the *Ping Ren Qi Xiang Lun* describes as "the pulse comes continuously like linked pearls, or like feeling polished jade (Langgan)."

The Qi turns westward, belonging to Metal. It corresponds to the Shen and You positions, and the season of Autumn, when all things are harvested. This Qi reaches its peak of dispersion and begins to contract from the exterior, like calm waves, clear smoke, and extinguished flames. In the human body, the Lung corresponds to this, manifesting as a Mao (Feather-like/Float) pulse. This is what the *Yu Ji Zhen Zang Lun* describes as "its Qi arrives light, void, floating, urgent, and scatters upon departure"; and the *Ping Ren Qi Xiang Lun* describes as "the pulse comes gently and softly, like falling elm seeds."

The Qi turns northward, belonging to Water. It corresponds to the Hai and Zi positions, and the season of Winter, when all things are stored. This Qi contracts, descends, and becomes solid, like fire buried in an oven or water gathered in a deep pool. In the human body, the Kidney corresponds to this, manifesting as a Shi (Stone-like/Sink) pulse. This is what the *Yu Ji Zhen Zang Lun* describes as "its Qi arrives deep and firm," and the *Ping Ren Qi Xiang Lun* describes as "the pulse comes panting, continuously like a hook, and feels firm upon pressure." (Note: The *Yu Ji Zhen Zang Lun* refers to the Winter pulse as Ying. Ying means gathering and storing within; the center must be solid, which is also the meaning of Shi. A Hook pulse that feels firm upon pressure possesses the meaning of Stone. Otherwise, it would be a Summer pulse.)

The descriptions of the four seasonal pulses in the above classics, although varying with time, always contain an image of gentleness and moderation. Gentleness and moderation belong to Earth and constitute Wei Qi (Stomach Qi). When Wei Qi combines with the seasonal pulse, it is a Ping Mai (Normal Pulse). The *Yu Ji Zhen Zang Lun* states: "The Spleen pulse belongs to Earth; it is the solitary organ that nourishes the four directions." The presence of this gentle and moderate quality within the Xian, Gou, Mao, and Shi pulses constitutes the nourishment of the four directions, representing Earth, and thus also represents the Spleen pulse. Because it resides within the four pulses, it is said that "the good [Spleen pulse] cannot be seen separately." The *Ping Ren Qi Xiang Lun* states: "Late Summer belongs to the Spleen; its pulse is soft and distinct, like a chicken treading on the ground." Observing this pulse image merely describes its gentleness. In the months of Chen, Xu, Chou, and Wei (the four seasons), Earth is prosperous for eighteen days each month, which signifies the meaning of nourishing the four directions. Thus, divided into four seasons, there is Earth but no visible Earth image. If discussing the Five Elements, it is analyzed into five. Earth resides in the center, belonging to Late Summer. Moreover, Late Summer lies between Metal and Fire, representing a transitional pulse of mutual generation, different from other seasons. Therefore, it alone can reveal the pulse of the ruling season. Although these two theories differ, their meanings do not contradict; they should be consulted together.

What is meant by Excessive (Tai Guo) and Deficient (Bu Ji)? It refers to the Xian, Gou, Mao, and Shi pulses responding to the season; they should all be gentle, moderate, and balanced. They should be slightly perceptible, not too obvious; they should faintly appear, not completely absent. Taking the Xian pulse as an example: if it is excessively slight yet becomes too string-like, it is called Excessive. Excess implies strong Qi. Strong Qi bulges outward, causing disease to arise from the exterior. If it is less than slightly string-like and lacks the string-like quality entirely, it is called Deficient. Deficiency implies weak Qi. Weak Qi shrinks inward, causing disease to arise from the interior. The Excessive and Deficient conditions of the Gou, Mao, and Shi pulses follow the same pattern.

Now, if one does not see the Excessive or Deficient nature of the Spring Xian pulse, but instead sees the Feathery and Floating pulse of Autumn, this represents a reversal of ascent into descent, and growth into killing. The mechanism of Qi is severely reversed, and the Shen (Spirit) cannot turn back. This is called Ke Ze (Overcoming and Robbing). There will be no survival without disease leading to death. Since Spring Wood is overcome by Metal, and the pathogenic Qi of Metal is vigorous on a Metal day, how can the righteous Qi endure? Hence, death occurs on this day. The same reasoning applies to deducing the condition of the five Zang organs, ensuring no errors.

Each season has its own pulse and its own diseases. However, since Earth nourishes the four directions, even if diseases manifest in myriad ways, they must take Wei Qi as the root. Moreover, Wei Qi is the essence of water and grain. The Shen (Vitality) in various pulses is the power derived from water and grain. Is it not heard that obtaining grain leads to prosperity? Indeed, this must be carefully examined.