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"Same appearance of cold and heat" refers to situations where cold and heat syndromes present with similar manifestations. Extreme cold may resemble heat, which is caused by Yin-cold pathogenic factors forcing the faint Yang-Qi to float outward; extreme heat may resemble cold, known as "the deeper the heat, the deeper the厥 (cold limbs)." Furthermore, there are cases where long-term use of warming and tonifying herbs leads to a mixture of clear and turbid Qi, resulting in abnormal aversion to cold. In such instances, treating with cold purgative formulas can allow Yang-Qi to penetrate and cold pathogens to recede. There are numerous famous discussions and clinical records by predecessors on this topic.

"Same disease" refers to the simultaneous presence of true cold and true heat pathogenic factors. For example, the Da Qing Long Tang syndrome in Shanghan (Cold Damage) involves external constraint by cold pathogens and internal depression of Wei-Qi (Defensive Qi), leading to transformation into heat. Patients with this condition typically have a pre-existing excess of stomach heat. Taiyang Zhong Yue (Heatstroke in the Taiyang stage) occurs when one is first injured by summer-heat and subsequently exposed to cold water, constituting a disease of simultaneous cold and heat invasion. The discussion on malaria in the Neijing (Classic of Internal Medicine) follows a similar logic. This represents exterior cold and interior heat. One must distinguish the depth and severity of the condition, as well as whether it affects the Qi level or Blood level, to apply differentiated treatment.

Exterior heat and interior cold may result from internal injury due to raw and cold foods combined with external exposure to scorching sun, leading to Huoluan (Cholera-like vomiting and diarrhea); or from indiscriminate consumption of fruits, melons, wine, and meat, leading to Liji (Dysentery). As for upper heat and lower cold, this is an internal deficiency disease characterized by lung heat and kidney cold. Alternatively, it may arise from lower body exposure to cold-dampness forcing Yang-Qi to ascend. Predecessors have provided famous discussions on these scenarios. However, the syndrome of upper cold and lower heat, representing the stagnation of True Yang, has become extremely common in recent times. The pulse is slippery or large upon deep palpation, and wiry or fine upon superficial palpation. The etiology may stem from long-term exposure to cold-dampness obstructing the free flow of Yang-Qi, or from excessive use of cooling and descending agents for minor heat symptoms. I often marvel that previous sages rarely mentioned this, until I read Xu Shuwei's case record involving Po Yin Dan, at which point I deeply admired his unique insight.

There is also a distinction between Qi-cold/Blood-heat and Blood-cold/Qi-heat, which corresponds to Zhang Zhongjing's concepts of Ying-cold/Wei-heat and Wei-cold/Ying-heat. When Blood is hot, the pulse form is slow and large; when Qi is cold, the pulse fluctuation is slight and forceless; when Blood is cold, the pulse form is tight and small; when Qi is hot, the pulse momentum is grand and forceful. This area was also overlooked by predecessors, except for Ye Tianshi's theory of unblocking collaterals, which aligns very well with the treatment methods for such diseases. I frequently borrow and apply his methods, achieving remarkably swift results.

Additionally, individuals whose constitution is inherently cold but suffer from heat injury, or those whose constitution is inherently hot but suffer from cold injury, often undergo mutual transformation over time. If the initial stage has not yet transformed, or if the pathogen is strong and does not transform, the treatment method should emulate the principle of "treating the dominant to pacify the latent" from the Neijing, to prevent recurrence or transformation after medication administration.