夫症者症也取症于外以验其中必心无疑似病无遁情乃可以云治也苟症有未明而漫为施治
其能
不误人者寡矣所以古人立四诊之法望以证其形色闻以证其音声问其起居饮食而得所因切其脉
象至息而知所病如此内外详审皆有明证然后从而治之无不得心应手故夫医之治病必若禹之治
水疏之瀹之决之排之顺水之性而无庸私智穿凿为也凡人身之经隧行有常度一失其平则阴阳不
和阴胜则阳病阳胜则阴病经义昭然有条不紊设延医者取证未确必至病在阴而反灸其阳病在阳
而反灸其阴宜灸多者反与之少则火力不及而病不能除宜灸少者反与之多则火力太过而病反增
剧更有禁灸之穴灸之损人尤不可不慎昔仓公论齐文王病引脉法曰年二十脉气当趋三十当疾步
四十当安坐五十当安卧六十以上气当大堇文王年未满二十方脉气之趋也而徐之不应天道四时
后
闻医灸之即笃此论病之过也故年二十是谓易质法不当砭灸砭灸至气逐又言齐北宫司空命妇出于
病
意诊其脉曰病气疝客于膀胱难于前后溲而溺赤灸其足厥阴之脉左右各一所即不遗溺而溲
清以
是知灸有所宜亦有所不宜在施治者具有灼见方可为人决死生拨乱反正而不失为良医然此事诚
有未易言者天有四时过不及之气地有东西南北寒热燥湿之不同人有老幼少壮膏粱藜藿之迥异
又有先富后贫先贵后贱所遇不遂所欲病机发于隐微治之者或同病异治或异病同治非生有灵敏
之质何能尽见人之五脏 结难经曰知一为下工知二为中工知三为上工上工者十全九中工者十
全八
下工者十全六由是观之医有脉证不明而能为人全治者乎无有也人所生病奇变百出有一病即有
一名名不正则言不顺言不顺则事不成古之人所以见垣一方者无他焉明证善治而已矣
病症的表现是外在的，通过观察外在症状来验证内在的病变，必须心中没有疑惑，病情没有隐瞒，才可以谈论治疗。如果症状不明确而随意进行治疗，能够不误人的情况是很少的。所以古人确立了望、闻、问、切四种诊法：望诊以验证病人的形色，闻诊以验证病人的声音和气息，问诊通过询问起居饮食来了解病因，切诊通过触摸脉象和呼吸节奏来知晓疾病所在。这样内外详细审查，都有明确的证据，然后据此进行治疗，就能得心应手。
因此，医生治病应当像大禹治水一样，疏通河道、宣泄积水、开决障碍、排除堵塞，顺应水的本性，而不需要凭借个人的私智去穿凿附会。凡是人体经络的运行有一定的常规度数，一旦失去平衡，就会导致阴阳不和；阴气偏胜则阳气受病，阳气偏胜则阴气受病。经义明确，有条不紊。如果延请医生时取证不准确，必然会导致病在阴部却反而灸治阳部，病在阳部却反而灸治阴部。适宜多灸的反而给予少灸，则火力不足，疾病不能消除；适宜少灸的反而给予多灸，则火力太过，疾病反而加剧。更有禁灸的穴位，灸之会损伤人体，尤其不可不谨慎。
从前仓公论述齐文王的病情，引用脉法说：“二十岁时脉气应当趋向于快速，三十岁应当疾步，四十岁应当安坐，五十岁应当安卧，六十岁以上气应当非常衰弱。”齐文王年龄未满二十岁，正是脉气趋向快速的阶段，但脉象迟缓不应，这是违背了天道四时的规律。后来听说医生用灸法治他，病情就加重了，这是诊断疾病的过错。所以二十岁称为“易质”（体质变化快的阶段），法度上不当使用砭石和灸法。如果滥用砭灸，会导致气机耗散。
又曾诊治齐北宫司空命妇的病，诊察她的脉象说：“病气疝邪客居在膀胱，导致大小便困难且尿色发红。”灸治足厥阴肝经的穴位左右各一个，结果就不再遗尿且小便清亮。由此可知，灸法有所适宜，也有所不适宜。在于施治者具有独到的见解，才能为病人决断生死，拨乱反正，而不失为良医。然而这件事确实不容易言说。天有四时，有过盛和不足之气；地有东西南北，寒热燥湿各不相同；人有老幼少壮，饮食有膏粱厚味与藜藿粗食的巨大差异；又有先富后贫、先贵后贱，遭遇不顺、欲望未遂的情况。病机发源于隐微之处，治疗者有的同病异治，有的异病同治。如果不是天生具有灵敏的资质，怎么能完全看清人的五脏结聚？《难经》说：“懂得一种诊法的为下工，懂得两种诊法的为中工，懂得三种诊法的为上工。上工治愈率十分之九，中工治愈率十分之八，下工治愈率十分之六。”由此看来，医生如果在脉证不明的情况下能为人完全治好病吗？是没有的。人所生的疾病奇变百出，有一种病就有一个名称，名称不正确则言语不顺，言语不顺则事情办不成。古代那些能洞察病灶的人，没有其他原因，只是明察证据、善于治疗罢了。
Symptoms manifest externally; by observing external symptoms, one verifies internal pathology. Only when the mind is free from doubt and the disease reveals no hidden aspects can treatment be discussed. If symptoms are unclear yet treatment is administered arbitrarily, few cases will avoid harming the patient. Therefore, the ancients established the Four Diagnostic Methods (Si Zhen): Inspection (Wang) to verify physical appearance and complexion; Auscultation and Olfaction (Wen) to verify voice and breath; Inquiry (Wen) to ascertain etiology through asking about daily life and diet; and Palpation (Qie) to determine the disease by feeling the pulse and respiration. Thus, with detailed internal and external examination yielding clear evidence, subsequent treatment becomes effortless and effective.
Therefore, a physician treating disease should be like Yu the Great controlling the waters: dredging channels, venting accumulation, opening blockages, and removing obstructions, following the nature of water without relying on personal ingenuity or forced interventions. The meridians (Jing Sui) in the human body follow constant rules; once balance is lost, Yin and Yang become disharmonious. Excess Yin leads to Yang pathology, and excess Yang leads to Yin pathology. This principle is clear and orderly. If a physician gathers evidence inaccurately, it inevitably results in moxibustion applied to Yang sites for Yin diseases, and to Yin sites for Yang diseases. Where excessive moxibustion is indicated but insufficient heat is applied, the fire power fails to eliminate the disease; where minimal moxibustion is indicated but excessive heat is applied, the fire power becomes too strong, aggravating the disease. Furthermore, there are acupoints contraindicated for moxibustion (Jin Jiu); applying them causes harm and requires utmost caution.
In the past, Cang Gong discussed the illness of King Wen of Qi, citing pulse theory: "At twenty, pulse qi should tend towards rapidity; at thirty, towards brisk walking; at forty, towards sitting calmly; at fifty, towards lying down; above sixty, qi should be greatly diminished." King Wen was under twenty, a time when pulse qi tends towards rapidity, yet his pulse was slow and unresponsive, violating the Heavenly Dao and the four seasons. Later, hearing that physicians used moxibustion, his condition worsened; this was an error in diagnosing the disease. Thus, at twenty, one is called having a "changeable constitution" (Yi Zhi), and according to protocol, Bian stone (Bian Shi) and moxibustion should not be used. Abusing these methods exhausts the qi.
He also treated a woman from the North Palace of Qi,司空 (Sikong). Upon palpating her pulse, he said: "The pathogenic qi of hernia resides in the Bladder, causing difficulty in urination and defecation, with red urine." Moxibustion was applied to the Foot-Jueyin Liver Meridian (Zu Jueyin Gan Mai) at one point on each side. Consequently, urinary incontinence ceased, and urination became clear. From this, we know that moxibustion has its appropriate and inappropriate applications. It depends on the practitioner's profound insight to determine life and death, correct chaos, and remain a good physician. However, this matter is indeed difficult to discuss. Heaven has four seasons with excess and deficient energies; Earth has differences in cold, heat, dryness, and moisture across directions; Humans vary in age (old, young, vigorous) and diet (rich vs. coarse food). There are also changes from wealth to poverty, status to obscurity, and unfulfilled desires. Pathogenesis arises subtly; treatments may differ for the same disease or converge for different diseases. Without innate sensitivity, how can one fully perceive the knotting of the Five Zang Organs? The *Nan Jing* states: "Knowing one method makes a Lower Physician; knowing two, a Middle Physician; knowing three, an Upper Physician. The Upper Physician cures nine out of ten; the Middle Physician, eight out of ten; the Lower Physician, six out of ten." Thus, can a physician completely cure a patient without clear pulse and symptom differentiation? No. Diseases manifest in myriad variations; each disease has a name. If the name is incorrect, speech is disordered; if speech is disordered, affairs fail. Those ancient masters who could see the lesion from afar did so for no other reason than their clarity in evidence and skill in treatment.