李东垣曰∶夫疮肿之疾，毒瓦斯已结者，不可论内消之法，即当辨脓生熟浅深，不
可妄开，视之可否，不至于危殆矣。凡疮疽肿大，按之乃痛者，脓深也；小按之便
痛者，脓浅也；按之不甚痛者，未成脓也；若按之即复者，有脓也；不复者，无脓也，
非也，必有水也。以手掩其上，大热者，脓成而自软也；若其薄皮剥起者，脓成也；其
肿不甚热者，脓未成也。（《十书》）
经曰∶脓血交粘，用药可全，色鲜红活，腐肉易脱，气败血衰，神仙叹哉。
齐氏曰∶若发肿部软而不痛者，血瘤也。发肿日渐增长，而不大热，时时牵痛
者，气瘤也。气结微肿，久而不消，后亦成脓，此是寒热所为也。留积经久，极阴
生阳，寒化为热，以此溃者，必多成瘤。
伍氏曰∶疮肿赤色，按之色不变者，此脓已成也；按之随手赤色者，其亦有脓也；
按之白色，良久方赤者，此游毒已息，可就赤白尽处灸断，赤肿自消。凡以手按之。
若牢硬，未有脓也；若半软半硬，已有脓也。又按肿上下不热者为无脓；热甚者，为有脓，宜急破之。
澄曰∶凡肿疡按之软陷，随手起者，为有脓；按之坚硬，虽按之有凹，不即随手
起者，为脓尚未成，不可轻易决破。又曰∶凡大按乃痛者病深，小按便痛者病浅；按
之处陷不复者无脓，按之处即复者有脓；按之不复者可消，若按之都牵强者未有脓也。
按之半软者，有脓也。又以手按上下，不热者无脓，若热者有脓。凡觉有脓，急当
破之；无脓但气肿，若有血，慎之，慎之，不可针破也，用诸拔毒之药敷散。四围坚，
中间软者，此为有脓也；一边软，亦可有脓。都坚硬者，此为恶核，或有气也；都
软者，此为有血或血瘤也，当审坚硬虚实为要。若坚疽积久，后若更变热中有软处，
当软处切不可针破也；软疽者，只温暖裹衣置之耳。若针灸刺破，不可疗矣。
Li Dongyuan stated: For diseases of sores and swellings, if the pathogenic toxins have already condensed, internal resolution methods should not be discussed. Instead, one must distinguish whether the pus is mature or immature, and its depth or superficiality. One must not rashly incise; by observing whether it is suitable for treatment, critical danger can be avoided. Generally, when a sore or carbuncle is swollen and large, pain occurs only upon deep pressure, indicating that the pus is deep; pain upon slight pressure indicates that the pus is superficial; insignificant pain upon pressure indicates that pus has not yet formed. If the area rebounds immediately after pressure, there is pus; if it does not rebound, it is incorrect to say there is no pus; rather, there must be fluid retention. Covering the area with the hand, intense heat indicates that the pus has matured and become soft; if the thin skin peels up, the pus has matured; if the swelling is not very hot, the pus has not yet formed. (From *Ten Books*)
The Classics state: When pus and blood are sticky and mixed, medication can lead to complete recovery; when the color is fresh and vibrant, necrotic tissue easily detaches; but if qi is exhausted and blood is depleted, even immortals would sigh in despair.
Qi stated: If the affected area is swollen and soft but painless, it is a blood tumor (*xueliu*). If the swelling increases day by day without significant heat, accompanied by occasional pulling pain, it is a qi tumor (*qiliu*). Qi stagnation causes slight swelling that persists for a long time without resolving, eventually turning into pus; this is caused by cold and heat pathogens. Pathogenic factors accumulating over a long period transform extreme yin into yang, and cold transforms into heat. Therefore, ulcers resulting from this transformation often form tumors.
Wu stated: If a sore or swelling is red and the color does not change upon pressure, the pus has formed; if the area turns red immediately upon pressure, there is also pus; if it appears white upon pressure and only turns red after a long time, the wandering toxin has subsided. Moxibustion can be applied at the boundary between red and white areas to cut off the toxin, and the redness and swelling will naturally subside. Generally, upon manual pressure, if the texture is firm and hard, there is no pus; if it is half-soft and half-hard, there is pus. Additionally, pressing the upper and lower parts of the swelling: if cool, there is no pus; if very hot, there is pus, and urgent incision is indicated.
Cheng stated: For any ulcerative swelling, if it feels soft and sinks upon pressure, rebounding immediately upon release, there is pus; if it feels hard, and although it sinks under pressure, it does not rebound immediately, the pus has not yet formed, and one must not rashly incise. He further stated: Pain upon deep pressure indicates a deep lesion; pain upon slight pressure indicates a superficial lesion. An indentation that does not recover indicates no pus; an indentation that recovers immediately indicates pus. An indentation that does not recover may resolve through dispersion; if the area feels tight and stiff upon pressure, there is no pus. A semi-soft area upon pressure indicates pus. Pressing the upper and lower parts of the swelling: if cool, there is no pus; if hot, there is pus. Whenever pus is suspected, urgent incision is required. If there is no pus but only qi swelling, or if there is blood stasis, one must be extremely cautious and never use needles to puncture; instead, apply various detoxifying herbs externally to dissipate the swelling. If the periphery is hard and the center is soft, this indicates pus; if one side is soft, pus may also be present. If the entire area is hard, this is a "malignant nodule" (*ehe*), possibly due to qi stagnation; if the entire area is soft, this indicates blood stasis or a blood tumor. It is essential to examine hardness versus flaccidity. If a hard carbuncle persists for a long time and later develops heat with soft spots, these soft spots must absolutely not be punctured with needles; for soft carbuncles, simply keeping them warm with wrapped clothing is sufficient. If treated with acupuncture or needle incision, they cannot be cured.