(Physicians) who can articulate medical principles but do not understand the rationale behind previous physicians' prescriptions and herb usage will therefore rarely use these formulas, which is hardly surprising. A pulse that is slow (Huan) and floating (Fu) indicates Wind Strike (Zhong Feng, an exterior deficiency syndrome caused by wind pathogen); thus, the patient experiences aversion to wind, chills, and fever. Zhang Zhongjing prescribes Guizhi Tang (Cinnamon Twig Decoction) to treat this. A pulse that is floating, tight, and choppy indicates Cold Damage (Shang Han, an exterior excess syndrome caused by cold pathogen); thus, the patient experiences headache, fever, body pain, lower back pain, joint pain, aversion to cold, absence of sweating, and wheezing. Zhang Zhongjing prescribes Mahuang Tang (Ephedra Decoction) to treat this. As for cases where Wind Strike presents with a floating-tight pulse, or Cold Damage presents with a floating-slow pulse, Zhang Zhongjing prescribes Da Qing Long Tang (Major Blue Green Dragon Decoction) for both. Why? I have deeply investigated the underlying principles. If the symptoms correspond accurately with the pulse, recovery follows immediately. Why is this so? Wind damages Wei Qi (Defensive Qi), while Cold damages Ying Blood (Nutritive Blood). Ying Blood circulates within the vessels, while Wei Qi circulates outside the vessels. When wind damages Wei Qi, the wind pathogen interferes with Yang Qi, causing it to become insecure and disperse as sweat; hence, spontaneous sweating occurs. This represents Exterior Deficiency. Therefore, Zhang Zhongjing uses Guizhi (Cinnamon Twig) to dispel the pathogen and Shaoyao (White Peony Root) to harmonize the blood. Generally, in Wind Strike, the pathology lies outside the vessels, and the disease...