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The general principles of the Hidden Pulse (Fu Mai, 伏脉) have been exhaustively discussed in *Jianmo Buyi* (Supplementary Commentary on Jianmo). Tao Jie'an stated that when the pulses in both hands suddenly become hidden in patients with Cold Damage (Shanghan, 伤寒), this indicates that sweating is imminent. The sweat induced by pathogenic factors requires dispersing treatment, whereas normal physiological sweating does not. However, he did not point out the underlying reason for this sudden hiding of the pulse.

In cases where sweating is desired but the pulse suddenly becomes hidden, it is generally because pathogenic factors have stagnated and entered the blood vessels. The healthy Qi attempts to extend but is obstructed by the blood, preventing it from extending abruptly. This frustrates the initial sharp momentum of the healthy Qi, leading to mutual obstruction between the healthy Qi and the pathogen. Alternatively, in prolonged Cold Damage, Yin excess and Yang deficiency cause the blood vessels to congeal and flow sluggishly. Upon administering warming and tonifying formulas, Yang Qi suddenly fills and surges into the blood vessels. Since the cold pathogen cannot dissipate abruptly, the two contend, causing a sudden obstruction of Qi mechanism. In severe Warm Diseases (Wenbing, 温病) with high fever, fluids are scorched and blood becomes dry. After administering fluid-nourishing formulas, as fluids begin to return and healthy Qi drives them into the blood vessels, the dry blood cannot be moistened abruptly, and the Qi mechanism cannot flow smoothly immediately. This mutual pressure leads to closure. There are also cases of internal injury from raw/cold foods and external contraction of wind-cold, presenting with chest constriction and pain, and rapid breathing. After administering warming and resolving formulas, Spleen Yang suddenly activates, and cold food begins to digest. However, since exterior pathogens remain unresolved, mutual rejection occurs, causing sudden Qi obstruction. Furthermore, in cases of internal accumulation of dry stool with lingering exterior pathogens, after administering moistening and purging formulas, as dry stool prepares to descend, healthy Qi moves inward and fails to defend the exterior. Seizing the opportunity, exterior pathogens shift inward, while healthy Qi rotates back outward. This mutual agitation causes sudden Qi obstruction. All these scenarios result from Qi urgently seeking unobstruction but failing to achieve it abruptly.

If a patient who already has sweating or persistent diarrhea suddenly presents with no pulse, this indicates the dispersion of True Qi and Qi collapse. Another scenario involves prolonged Wind Injury or prior misapplication of diaphoresis, leading to Yin deficiency with floating Yang (Daiyang, 戴阳), depleted fluids, and knotted Qi. When Qi contends at the exterior, the pulse may appear floating and thin, confined to the skin and hair level, scattering upon slight pressure. After administering fluid-generating formulas, Yang Qi suddenly interacts with Yin, and the pulse becomes contained internally. Why? Because Qi must first inhale before it can exhale. If this condition is treated with pungent-warm herbs to force sweating without first generating fluids, the pulse Qi will not hide beforehand; instead, immediate sweating will occur, leading instantly to panting and Qi collapse. The former type of Hidden Pulse represents the contention between pathogenic and healthy Qi, while the latter represents the interaction between Yin and Yang. The sweating obtained in both cases belongs to what is termed "Zhanhan" (Battle Sweat, 战汗). In cases of pathogenic-healthy Qi contention, restlessness is often severe, which Wu Youke described as "Kuanghan" (Mad Sweat, 狂汗). In cases of Yin-Yang interaction, healthy Qi is weak and pathogens are mild, manifesting only slightly as clenched jaws and cold extremities. Tao Jie'an distinguished between Zhenghan (Normal Sweat, 正汗) and Xiehan (Pathogenic Sweat, 邪汗). Pathogenic sweat results from the contention of pathogenic and healthy Qi; hence, it is said to require dispersing, meaning to assist the healthy Qi.