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In the treatment of *Shanghan* (Cold Damage), one should not be bound by the number of days since onset. Whenever exterior syndrome is observed, treat the exterior; whenever interior syndrome is observed, treat the interior. Differentiating the meridians based on symptoms and applying treatments according to the affected meridians constitutes a sound method. If exterior pathogenic factors have not yet resolved, even if many days have passed, provided that exterior signs are present and the pulse is tight or rapid, one must still resolve the exterior and must not attack the interior. Conversely, if exterior pathogenic factors have lightened, even if few days have passed, provided that interior signs are present and the pulse is deep and excess, one must attack the interior and must not induce sweating to release the exterior. However, these two approaches—releasing the exterior (*Fabiao*, dispersing pathogens from the surface) and attacking the interior (*Gongli*, purging internal accumulation)—both refer to conditions characterized by excess pathogenic factors. In cases where there is insufficiency of pulse qi and physical vitality, neither releasing the exterior nor attacking the interior should be employed; instead, tonification should be adopted. Tonification varies in degree: sometimes it is appropriate to combine tonification with other methods, and sometimes full tonification is required. This depends on the physician's wisdom and adherence to proper protocols.

First, in *Shanghan*, if fever and aversion to cold, a tight and rapid pulse, absence of sweating, pain in the head and nape, stiffness of the waist and spine, or soreness and weakness of the limbs are observed, this indicates an exterior syndrome. Regardless of the number of days elapsed, immediate resolution of the exterior is required. However, differentiation of Yin and Yang deficiency or excess must be conducted beforehand, and appropriate formulas from the subsequent list of diaphoretic prescriptions should be selected for use.

Second, in *Shanghan*, if alternating chills and fever, hypochondriac pain, bitter taste in the mouth with vomiting, gradual hearing loss, or a wiry and rapid pulse are observed, this indicates a Shaoyang meridian syndrome located half-exterior and half-interior. The treatment should aim at harmonizing, using formulas such as Xin Fang Zhu Chaihu Yin (New Formula Various Bupleurum Decoctions) or Xiao Chaihu Tang (Minor Bupleurum Decoction), selected as appropriate. However, there are three prohibitions in treating Shaoyang disorders: sweating, emesis, and purgation are all contraindicated.

Third, if in *Shanghan* the exterior signs such as headache, fever, and aversion to cold have completely disappeared, and instead there is heat intolerance, restlessness, thirst, delirium, tossing off clothes and bedding, waving hands and kicking feet, appearance of macules and jaundice, or mania, along with tidal fever, spontaneous sweating, constipation, scanty dark urine, chest and abdominal distension, fullness, pain, shortness of breath, and a forceful excess pulse, this indicates a heat syndrome transmitted to the interior. Regardless of the number of days, clearing the interior heat is required. If excess pathogens are internally accumulated and obstructing free flow, vigorous purging is necessary to unblock the interior, which will consequently unblock the exterior. However, purgation is only permissible when there is significant chest and abdominal distension, dry fecal impaction in the intestines and stomach, and severe fullness, excess, and hardness. Thus, the method states: only after the five conditions of obstruction (*Pi*), fullness (*Man*), dryness (*Zao*), excess (*Shi*), and hardness (*Jian*) are present can purgation be applied. It is also said: "Purgation should not be performed too early." This caution exists because mistakenly purging a non-excess condition will inevitably lead to untreatable collapse.

Fourth, in treating *Shanghan*, if the seasonal climate is cold and internal Yang is weak, with no internal heat but unresolved exterior syndrome, acrid-warm-hot agents should be used to disperse; if the seasonal climate is hot and fire is prevalent with unresolved exterior syndrome, acrid-sweet-cool agents should be used to disperse; if the seasonal climate is balanced with unresolved exterior syndrome, acrid-sweet-neutral agents should be used to disperse. These are essential methods for resolving the exterior. Humans exist within the interaction of Qi between Heaven and Earth and transform accordingly. When the Qi of Heaven and Earth is cold, acrid-warm agents are suitable; when hot, acrid-cool agents are suitable. Since the Classics designate winter diseases as *Shanghan*, spring diseases as Warm Diseases (*Wenbing*), and summer diseases as Heat Diseases (*Shubing*), and names change with the seasons, formulas must also adapt to the times. However, when using cool dispersal methods, careful differentiation is required. Cool agents may be combined only if both exterior and interior exhibit heat signs. If the body surface is hot but there are no internal heat signs, this heat arises from exterior pathogens constrained by cold. In such cases, cool medicines must not be used recklessly. There is a risk that if exterior cold is not removed and internal cold subsequently arrives, cold meeting cold will cause coagulation without resolution, worsening the condition. The Classic states: "Releasing the exterior does not avoid heat," which refers precisely to this principle. Furthermore, "setting aside the season to follow the syndrome" (*She Shi Cong Zheng*) is a critical method in treating *Shanghan*, and understanding the balance between routine and flexibility is indispensable.

Fifth, when summer-heat is rampant and plagues arise extensively, presenting with extreme thirst, macules, jaundice, and organs feeling like burning furnaces, one may either use cold-astringent agents to clear the interior or cold-dispersal agents to rescue the exterior. The key is to examine the exterior and interior status and determine the appropriate urgency of treatment.