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The Xi (Fine) pulse is smaller than the Wei (Minute) pulse but persists; it is straight and soft, feeling like a silk thread under the fingers (*Mai Jing*). The *Su Wen* refers to it as "Xiao" (Small). Wang Qixuan described it as resembling the downy seeds of a weed, characterizing its softness and fineness. The *Mai Jue* states: "Coming and going extremely minute," which implies that the Wei pulse appears larger than the Xi pulse, contradicting the meaning in the *Jing*.

[Body Form Poem] The Xi pulse comes and goes continuously, fine as silk, pressing steadily without interruption. It is unfavorable for spring and summer, and for the young; however, it is suitable for autumn and winter, and for the elderly or weak.

[Similarity Poem] See Wei (Minute) and Ru (Floating Soft) pulses.

[Main Disease Poem] The lingering Xi pulse indicates depletion of blood and Qi, various deficiency consumptions, and emotional disharmony. If not caused by dampness invading the waist and kidneys, it results from essence injury or excessive sweating. A Xi pulse at the Cun (Inch) position indicates frequent vomiting; at the Guan (Bar) position, abdominal distension due to stomach deficiency; at the Chi (Cubit) position, coldness in the Dantian, with symptoms such as diarrhea, dysentery, and seminal emission classified as Tuoyin (Collapse of Yin). The *Mai Jing* states: "Xi indicates insufficient blood and declining Qi." If these symptoms are present, the pulse matches the condition (Shun); otherwise, it is adverse. Therefore, patients with hematemesis or epistaxis who present with a Chen-Xi (Deep-Fine) pulse will survive. Those suffering from excessive worry and labor also have a Xi pulse.

The Fu (Hidden) pulse requires heavy pressure until the bone to feel the movement under the fingers (*Mai Jing*). The pulse travels beneath the tendons (*Kan Wu*). The *Mai Jue* states: "Searching lightly seems to have it, holding breath makes it disappear completely," which is highly erroneous.

[Body Form Poem] The Fu pulse must be sought by pushing aside tendons to press against the bone; the movement feels hidden and deep. In Shanghan (Cold Damage), when sweat is about to occur and Yang is resolving, or in Jueni (Cold Reversal) with umbilical pain, the syndrome belongs to Yin.

[Similarity Poem] See Chen (Deep) pulse.

[Main Disease Poem] The Fu pulse indicates Huoluan (Cholera-like disorder) with frequent vomiting; abdominal pain often stems from retained food. Accumulated fluids and old phlegm form masses; one must dispel cold and warm the interior without delay. Food stagnation in the chest causes both Cun positions to be Fu, with an urge to vomit that cannot be expelled, leading to constant discomfort. Abdominal pain at the Guan position feels heavy and sluggish; hernia pain behind the Guan may rupture the abdomen. In Shanghan, a Fu pulse in one hand is called Danfu (Single Hidden); in both hands, Shuangfu (Double Hidden). One should not diagnose Yin syndrome simply because Yin pulses appear in Yang syndromes. This occurs because Fire pathogen is internally constrained and cannot vent out; extreme Yang resembles Yin, so the pulse is Fu, and resolution must come through profuse sweating. This is like the sky darkening before rain after a long drought, after which all things revive upon rain. There is also Jiyin Shanghan (Cold Damage with Clamped Yin), where latent Yin exists internally, compounded by external cold invasion, leading to Yin excess and Yang decline, four extremities cold reversal, and six pulses sinking and hidden. One must administer Ginger and Aconite formulas and moxa Guanyuan (CV4) for the pulse to reappear. If Taixi (KI3) and Chongyang (ST42) pulses are absent, death is certain. The *Mai Jue* suggests "slowly inducing sweat." Jiegu used Fuzi Xixin Mahuang Tang (Aconite Twig, Asarum, and Ephedra Decoction) as the main treatment, both of which are incorrect. Liu Yuanbin stated: "The Fu pulse should not be treated with sweating methods."