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Mouth ulcers (Koumi) result from heat in the Heart and Spleen, with stagnant fire steaming upwards. Treatment should focus on clearing and purifying the Heart and Spleen; the pulse is typically surging and forceful, indicating an excess-heat pattern. In other cases, due to insufficiency of the Spleen's Yuan Qi and Middle Qi, which fails to anchor the Yin Fire from the Lower Jiao, mouth ulcers may also occur. In such instances, Fuzi Lizhong Tang (Aconite Decoction for Regulating the Middle) is appropriate; this distinction must not be overlooked. Regarding throat swelling, there are Yang Toxicity and Yin Toxicity. If the face is red, the pulse is surging, or pus and blood are vomited, it indicates Fire Qi rushing upward with heat in the Heart and Lungs, termed Yang Toxicity. If accompanied by cold limbs and a deep, fine pulse, it indicates Cold binding in the Lungs, where extreme Cold generates Heat and Damp-Heat steams upwards, termed Yin Toxicity. Yang Toxicity is treated by clearing the Lungs and resolving toxicity, while Yin Toxicity is treated by guiding Fire back to its source.

The feet contain three Yang meridians and three Yin meridians. Yang pulses are located at the five toes, while Yin pulses converge at the sole of the foot and gather below and above the knee. Thus, the *Classic* states: "When Yang Qi declines in the lower part, Cold Jue occurs; when Yin Qi declines in the lower part, Hot Jue occurs." Generally, when Yang Qi declines, Yin Qi prevails, causing coldness from the sole up to the knee, known as Yin Jue (Cold Reversal). However, if the condition extends beyond the knee, it is difficult to treat. When Yin Qi declines, Yang Qi prevails, resulting in heat that spreads from the five toes to the sole, known as Yang Jue (Hot Reversal). However, extreme heat may manifest with cold-like symptoms, i.e., "the deeper the heat, the deeper the reversal." Therefore, Yang Jue involves extreme heat leading to reversal, accompanied by irritability, thirst, rapid pulse, intermittent warmth of the body, constipation, dark urine, delirium, and confusion. It should be treated with Chengqi Tang (Gut-Purging Decoction) to purge downwards. Yin Jue involves no fever, diarrhea (as opposed to constipation), a slow, faint, and fine pulse, no thirst, a desire to cover oneself with clothes, and diarrhea. It should be treated with Sini Tang (Frigid Extremities Decoction). However, if Yang Jue reaches an extreme depth, causing cold body and a pulse so faint it seems about to cease, this indicates extreme heat approaching death. Urgently using Dachengqi Tang (Major Gut-Purging Decoction) to purge may reverse the Jue and restore life; this is what is meant by "cold medicines can paradoxically generate the pulse and warm the body." If hot medicines are mistakenly used to assist Yang, Yin Qi will abruptly perish, and Yang will also perish, leading to death. If Yin has already perished first, and Yang is also about to perish, using purgatives at this time will cause both Yin and Yang to exhaust, also leading to death. Can one fail to distinguish these carefully!