病之始生，浅则易治，久而深入，则难治。《内经》云∶圣人不治已病治未病。夫病已
成而
药之，譬犹渴而穿井，斗而铸兵，不亦晚乎！《伤寒论》序云∶时气不和，盒饭早言，寻其
邪由，及在腠理，以时治之，罕有不愈？患人忍之，数日乃说，邪气入脏，则难可制。昔扁
鹊齐桓公，云病在腠理，三见之后，则已入脏，不可治疗而逃矣。历圣相传，如同一辙。盖
病之始入，风寒既浅，气血脏腑未伤，自然治之甚易；至于邪气深入，则邪气与正气相乱，
欲攻邪则碍正；欲扶正则助邪，即使邪渐去，而正气已不支矣。若夫得病之后，更或劳动感
风，伤气伤食，谓之病后加病，尤极危殆。所以人之患病，在客馆道途得者，往往难治。非
所得之平凡独重也，乃既病之后，不能如在家之安适，而及早治之；又复劳动感冒，致病深
入而难治也。故凡人少有不适，必当实时调治，断不可忽为小病，以致渐深；更不可勉强支
持，使病更增，以贻无穷之害。此则凡人所当深省，而医者亦必询明其得病之故，更加意体
察也。
凡一病必有数症。有病同症异者，有症同病异者；有症与病相因者，有症与病不相因者
。盖
合之则曰病，分之则曰症。古方以一药治一症，合数症而成病，即合数药而成方。其中亦有
以一药治几症者，有合几药而治一症者，又有同此一症，因不同用药亦异，变化无穷。其浅
近易知者，哪吐逆用黄连、半夏；不寐用枣仁、茯神之类，人皆知之。至于零杂之症，如《
内经》所载，喘满噫语，吞欠嚏呕，笑泣目瞑，嗌干，心悬善恐，涎下涕出，啮唇啮舌，善
忘善怒，喜握多梦，呕酸魄汗等症，不可胜计。或由司天运气，或由脏腑生克，或由邪气传
变，《内经》言之最详。后之医者，病之总名亦不能知，安能于一病之中，辨明众症之渊源
？即使病者身受其苦，备细言之，而彼实茫然，不知古人以何药为治，仍以泛常不切之品应
命，并有用相反之药，以益其疾者。此病者之所以无门可告也。学医者，当熟读《内经》，
每症究其缘由，详其情状，辨其异同，审其真伪，然后遍考方书本草，详求古人治法。一遇
其症，应手辄愈。不知者以为神奇，其实古圣皆有成法也。
疾病在刚开始产生时，病位浅表，容易治疗；如果拖延日久，病邪深入体内，就难以治愈。《黄帝内经》说：高明的医生不治疗已经发生的疾病，而是预防未发生的疾病。既然疾病已经形成才用药治疗，这就好比口渴了才去挖井，打仗了才去铸造兵器，难道不也太晚了吗！《伤寒论》序言中说：当气候失常、人体不适时，应当尽早诊治，探寻致病邪气的来源，趁其还在皮肤腠理之间时及时治疗，很少有不痊愈的。患者忍受痛苦，过了几天才诉说病情，此时邪气已经传入脏腑，就很难控制了。从前扁鹊见齐桓公，说病在皮肤纹理间，经过三次见面后，病已深入脏腑，无法治疗而逃走了。历代圣贤传承的道理，都是如此一致。大概因为疾病初起时，风寒之邪尚浅，气血和脏腑尚未受损，自然很容易治疗；等到邪气深入，就会与正气相互扰乱，想要攻伐邪气则会损伤正气，想要扶助正气又会助长邪气，即使邪气逐渐消退，正气也已经支撑不住了。如果在患病之后，又因劳累或感受风邪，导致伤气或伤食，这叫做“病后加病”，尤其极其危险。所以人在旅途中、客馆里患的病，往往难治。并不是因为在那里得的病特别严重，而是因为生病之后，不能像在家那样安适，从而不能及早治疗；再加上劳累感冒，致使病邪深入而难治。因此，凡是身体稍有不适，必须当时调理治疗，绝对不可忽视认为是小病，以致病情逐渐加深；更不可勉强支撑，使病情加重，从而留下无穷的后患。这是普通人应当深刻反省的，而医生也必须详细询问得病的原因，更加用心体察。
任何一种疾病必然会有几种症状。有疾病相同但症状不同的，也有症状相同但疾病不同的；有症状与疾病互为因果的，也有症状与疾病没有直接关联的。综合起来称为“病”，分解开来称为“症”。古代方剂用一味药治疗一种症状，多种症状组合成疾病，也就对应多种药物组成方剂。其中也有一味药治疗几种症状的，有几种药合用治疗一种症状的，又有针对同一症状，因情况不同用药也各异，变化无穷。那些浅显易懂的知识，如呕吐逆运用黄连、半夏；失眠用酸枣仁、茯神之类，人们都知道。至于繁杂琐碎的症状，如《黄帝内经》所载的喘促胸满、打嗝言语不清、吞咽呵欠喷嚏呕吐、哭笑不止、眼睛闭合、咽喉干燥、心中空虚易惊恐、流涎流泪、咬唇咬舌、健忘易怒、喜欢握物多梦、呕吐酸水、魄汗（冷汗）等症状，数不胜数。这些或由司天运气（五运六气）引起，或由脏腑生克关系失调引起，或由邪气传变引起，《黄帝内经》阐述得非常详细。后来的医生，连疾病的总名称都不能知晓，又怎能在一类疾病中，辨明众多症状的渊源呢？即使患者身受其苦，详细陈述病情，而医生却茫然无知，不知道古人用什么药来治疗，仍然用平常且不切实际的药物应付差事，甚至有用性质相反的药物，反而加重病情的。这就是患者之所以无处求助的原因。学医的人，应当熟读《黄帝内经》，对每种症状都要探究其缘由，详查其情状，辨别其异同，审察其真伪，然后广泛考证方书和本草，详细探求古人的治疗方法。一旦遇到相应的症状，就能手到病除。不知情的人以为是神奇，其实古代圣贤都有既定的法则。
At the beginning of a disease, when it is superficial, it is easy to treat; but if it lingers and penetrates deeply, it becomes difficult to cure. The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: "The sage does not treat diseases that have already formed, but prevents those that have not yet arisen." To administer medicine only after a disease has established itself is akin to digging a well only when one is thirsty, or forging weapons only when battle has begun—is this not too late? The preface to the *Shanghan Lun* (Treatise on Cold Damage Disorders) says: "When the seasonal qi is discordant, [one] should speak early; trace the source of the pathogenic factor, and while it resides in the couli (skin and interstices), treat it in due course, and rarely will it not be cured." Patients endure [the discomfort] for several days before complaining; by then, the pathogenic qi has entered the zang organs, making it difficult to control. In the past, Bian Que told Duke Huan of Qi that the disease was in the couli; after three visits, it had entered the zang organs and could no longer be treated, leading to his escape. The teachings passed down through successive sages are all consistent. Generally, when a disease first enters, wind-cold is still superficial, and the qi, blood, and zang-fu organs are not yet damaged, so treatment is naturally very easy; however, once the pathogenic qi penetrates deeply, it confuses with the healthy qi. If one attempts to attack the pathogen, it harms the healthy qi; if one attempts to support the healthy qi, it aids the pathogen. Even if the pathogen gradually recedes, the healthy qi may already be unable to sustain itself. Furthermore, after contracting a disease, if one engages in labor or contracts wind, damaging qi or injuring food digestion, this is called "adding illness to illness," which is extremely critical. Therefore, illnesses contracted while traveling or staying in guesthouses are often difficult to treat. It is not that the illness acquired there is inherently heavier, but rather that after falling ill, one cannot enjoy the comfort of home to seek timely treatment; additionally, fatigue and cold exposure cause the pathogen to deepen, making it hard to cure. Thus, whenever one feels slight discomfort, immediate regulation and treatment are necessary. One must absolutely not ignore it as a minor ailment, allowing it to deepen gradually; nor should one force oneself to endure it, causing the illness to worsen and leaving endless harm. This is what ordinary people should reflect upon deeply, and what physicians must also inquire about clearly regarding the cause of the illness, observing with greater care.
Every disease necessarily presents with several symptoms. There are cases where the disease is the same but the symptoms differ, and cases where the symptoms are the same but the disease differs. There are symptoms that are causally linked to the disease, and those that are not. Collectively, they are referred to as "disease" (bing); individually analyzed, they are called "symptoms" (zheng). Ancient prescriptions used a single herb to treat a single symptom; combining multiple symptoms into a disease corresponds to combining multiple herbs into a formula. Within this framework, there are instances where one herb treats several symptoms, and where several herbs combine to treat one symptom. Moreover, for the same symptom, different medications may be used depending on the context, resulting in infinite variations. Those aspects that are shallow and easily understood, such as using Huanglian (Coptidis Rhizoma) and Banxia (Pinelliae Tuber) for vomiting and regurgitation, or Zaoren (Ziziphi Spinosomi Semen) and Fushen (Poria Cum Radix) for insomnia, are known to everyone. As for miscellaneous symptoms, such as those recorded in the *Huangdi Neijing*: panting and chest fullness, belching and dysarthria, swallowing, yawning, sneezing, vomiting, laughing, crying, closing eyes, dry throat, empty feeling in the heart with frequent fear, salivation and runny nose, biting lips and tongue, forgetfulness and irritability, desire to grasp objects, frequent dreaming, vomiting acid, pohans (cold sweat), etc., these are countless. These may arise from the influence of Si Tian Yun Qi (Dominant Qi of the Year), from the generation and restriction relationships among zang-fu organs, or from the transmission of pathogenic factors, all of which are detailed most extensively in the *Huangdi Neijing*. Later physicians, unable even to know the general name of the disease, how can they clarify the origins of various symptoms within a single disease? Even if the patient suffers greatly and explains the details, the physician remains bewildered, unaware of what ancient methods were used for treatment, and instead responds with generic, irrelevant substances, or even uses contraindicated herbs that exacerbate the illness. This is why patients feel they have no way to seek help. Students of medicine must diligently study the *Huangdi Neijing*, investigate the causes of each symptom, detail their manifestations, distinguish their similarities and differences, and verify their authenticity. Then, they should extensively consult formularies and materia medica, thoroughly seeking out the treatment methods of the ancients. Upon encountering such symptoms, they will achieve immediate cures. Those who do not understand consider this miraculous, but in reality, the ancient sages all established definitive protocols.