医者欲知病患脏腑，必要问其从内走出者，故凡病当验二便。仲景以小便不利，小便赤，定伤
寒里热；以小便利，小便白，定里无热。以大便不通，大便硬，定其里热；自下利，下利厥
冷，定其里寒。故治病以二便定人寒热，以二便定人燥湿，以二便定人虚实，再无差误。然
论二便亦宜细详。例如大便干结，知其热矣；然大便滑泄，黄色为热，人多忽之矣。小便黄
赤，知其热矣；然小便色白而混浊，亦为热，人多忽之矣。又如大便干结，知其热矣；亦有
血枯津竭，用不得苦寒者。又如小便黄赤，知其热矣；亦有食滞中焦，黄赤混浊，用寒凉反
不清，用香燥辛温而清利者。
伤寒，症有表里阴阳四大关节，脉有浮沉迟数四大分别。夫浮则为表，沉则为里，迟则为
寒，数则为热，此以浮沉分表里，迟数分寒热者也。夫伤寒，热病也，其脉必数；中寒，阴
症也，其脉必迟。若见数脉，即症在阴经，亦是阳邪传入之热病；若见数脉，即手足厥冷，
亦是热深厥深、阳症似阴之假像。故治伤寒，一见浮数，此是表有邪热，当照三阳发表治
之。若一见沉数，此是里有热邪，即表症急者，虽先治表，然亦禁辛温而用辛凉双解之法；
苟表症一解，即当清里。此以脉之发现二条而论也。若沉伏之脉，有三条分别。有阳症脉沉
伏，非阴症里寒也，阳邪内伏，不得作汗外出，禁用寒凉，只宜升散表邪，则汗出而脉亦
出。又有阳症脉微，此正气虚微，不得作汗，用发表之药，以散阳邪，加人参少许，助正气
虚微，则散表之药，得人参愈能散表，虽阳症阴脉之死症，如此治之，亦有得生者。又有脏气
虚寒，脉见沉迟，此阴症中寒也，急宜温经救里。此以沉脉中，别出伏邪、正虚、阴寒三条
者也。夫阴症脉沉者，沉而迟漫分明者也。伏邪脉沉者，沉而伏匿，急数模糊者也。正虚脉
微者，不拘浮沉，脉来衰微，按久无力者也。故凡迟漫分明者，里寒也。沉伏不出者，表邪
不得发越也。阳症脉微者，邪盛正虚也。今有阳邪之症，而见沉伏之脉，误认阴症而用温
热，阳邪内发，死不旋踵。若见烦躁不宁，误用寒凉，则表汗抑遏。故切脉之道，先分症是
何症，然后以脉消息者也。夫脉沉当下，若表症急者，仍先散表。脉浮当汗，若里有热者
又不得不和解表里；下症急者，又不得不双解表里。
医生想要了解病患脏腑的情况，必须询问从体内排出的物质，因此凡是疾病都应当检查大小便。张仲景根据小便不通畅、小便颜色红赤，来确定伤寒里有热邪；根据小便通畅、小便颜色清白，来确定里没有热邪。根据大便不通、大便干硬，来确定其里有热邪；根据自行下利、下利且四肢厥冷，来确定其里有寒邪。所以治病通过二便来判断人的寒热属性，通过二便来判断人的燥湿状态，通过二便来判断人的虚实状况，就不会再有差错。然而论述二便也应当仔细详察。例如大便干结，知道是有热邪了；但是大便滑泄，如果颜色发黄则属于热邪，人们往往忽略了这一点。小便黄赤，知道是有热邪了；但是小便颜色白而混浊，也属于热邪，人们往往忽略了这一点。又如大便干结，知道是有热邪了；但也有因血枯津液枯竭导致的，这种情况下不能用苦寒的药物。又如小便黄赤，知道是有热邪了；但也有因食积停滞在中焦，导致小便黄赤混浊，用寒凉药反而不能清除病邪，用芳香燥烈辛温的药却能清利病邪的情况。
伤寒病症有表、里、阴、阳四大关键节点，脉象有浮、沉、迟、数四大分别。浮脉主表证，沉脉主里证，迟脉主寒证，数脉主热证，这是以浮沉来区分表里，以迟数来区分寒热的方法。伤寒是热病，其脉象必然为数脉；中寒是阴证，其脉象必然为迟脉。如果见到数脉，即使症状表现在阴经，也是阳邪传入引起的热病；如果见到数脉，即使手足厥冷，也是热邪深重导致四肢厥冷（热深厥深）、阳证表现出类似阴证的假象。所以治疗伤寒，一见到浮数脉，这是表有邪热，应当按照三阳经的解表法治疗。如果一见到沉数脉，这是里有热邪，即使表证紧急，虽然先治表证，但也禁止使用辛温药物，而应使用辛凉双解的方法；一旦表证解除，就应当清解里热。这是根据脉象显现的两条原则来论述的。如果是沉伏脉，有三种分别情况。有阳证出现脉沉伏，并非阴证里寒，而是阳邪内伏，无法通过发汗外出，此时禁用寒凉药，只适宜升散表邪，这样汗出后脉象也会显露出来。又有阳证出现脉微，这是正气虚微，无法发汗，使用发表药物以疏散阳邪时，加入少许人参，辅助虚微的正气，那么发表药物得人参相助更能发散表邪，即使是阳证见阴脉的死症，这样治疗也有存活的可能。又有脏气虚寒，脉象呈现沉迟，这是阴证中寒，急需温经救里。这是从沉脉中，辨别出伏邪、正虚、阴寒三种情况。阴证脉沉的，是沉而迟缓清晰的。伏邪脉沉的，是沉而潜伏隐匿，急数模糊的。正虚脉微的，不拘泥于浮沉，脉来衰微，按压久了无力。所以凡是迟缓清晰的，是里寒。沉伏不出来的，是表邪不得发散。阳证脉微的，是邪盛正虚。现在有阳邪的症状，却见到沉伏的脉象，误认为是阴证而使用温热药，会导致阳邪内发，死亡很快。如果见到烦躁不宁，误用寒凉药，则会抑制表汗排出。所以切脉的道理，先要分清症状是什么证，然后再根据脉象来斟酌处理。脉沉应当攻下，如果表证紧急，仍然先解散表邪。脉浮应当发汗，如果里有热邪，又不得不和解表里；下证紧急，又不得不双解表里。
To understand the condition of a patient's Zang-Fu organs, a physician must inquire about what is discharged from the interior; therefore, in all diseases, one should examine the urine and stool. Zhang Zhongjing determined that interior heat in Shanghan (Cold Damage) by the presence of difficult urination and dark red urine, and determined the absence of interior heat by clear, unobstructed urination with pale urine. He determined interior heat by constipation and hard stools, and interior cold by spontaneous diarrhea accompanied by cold extremities. Thus, by examining the urine and stool, one can determine a person's cold or heat nature, dryness or dampness state, and deficiency or excess condition, without error. However, the discussion of urine and stool requires careful scrutiny. For instance, dry and bound stools indicate heat; yet, slippery diarrhea with yellow color also indicates heat, which people often overlook. Yellow-red urine indicates heat; yet, white but turbid urine can also indicate heat, which people often overlook. Again, dry and bound stools indicate heat; however, there are cases of blood depletion and fluid exhaustion where bitter-cold herbs are contraindicated. Similarly, yellow-red urine indicates heat; however, there are cases of food stagnation in the Middle Jiao causing yellow-red turbid urine, where cold-cooling herbs fail to clear the pathogen, while aromatic, drying, pungent, and warm herbs succeed in clearing and promoting diuresis.
Shanghan symptoms have four major junctions: Exterior, Interior, Yin, and Yang. Pulse qualities have four major distinctions: Floating, Sinking, Slow, and Rapid. A Floating pulse indicates an Exterior syndrome, a Sinking pulse indicates an Interior syndrome, a Slow pulse indicates Cold, and a Rapid pulse indicates Heat. This method uses Floating and Sinking to distinguish Exterior and Interior, and Slow and Rapid to distinguish Cold and Heat. Shanghan is a heat disease, so its pulse must be Rapid; Zhonghan (Cold Strike) is a Yin syndrome, so its pulse must be Slow. If a Rapid pulse is seen, even if symptoms manifest in the Yin meridians, it is still a heat disease caused by the transmission of Yang pathogens. If a Rapid pulse is seen, even if the hands and feet are cold, it is "deep heat leading to deep cold" (Re Shen Jue Shen), a false appearance of a Yang syndrome resembling Yin. Therefore, when treating Shanghan, upon seeing a Floating-Rapid pulse, indicating exterior pathogenic heat, one should treat according to the releasing-the-exterior methods of the Three Yang meridians. Upon seeing a Sinking-Rapid pulse, indicating interior pathogenic heat, even if the exterior syndrome is urgent, although the exterior is treated first, pungent-warm herbs are prohibited; instead, a method of pungent-cool dual resolution should be used. Once the exterior syndrome is resolved, the interior should be cleared. This discusses two principles based on pulse manifestation. Regarding the Sinking-Hidden pulse, there are three distinctions. One case is a Yang syndrome with a Sinking-Hidden pulse, which is not a Yin syndrome with interior cold, but rather Yang pathogens hidden internally, preventing sweating and exit; cold-cooling herbs are prohibited, and only ascending and dispersing methods for exterior pathogens are suitable, so that upon sweating, the pulse emerges. Another case is a Yang syndrome with a Micro pulse, indicating deficient and weak righteous Qi unable to sweat; when using releasing herbs to disperse Yang pathogens, a small amount of Renshen (Ginseng Radix et Rhizoma) is added to assist the deficient righteous Qi, allowing the releasing herbs to work better with Ginseng. Even in fatal cases of Yang syndrome with Yin pulse, such treatment may lead to survival. Another case is deficiency-cold of the Zang organs with a Sinking-Slow pulse, indicating Yin syndrome with Cold Strike, requiring urgent warming of the meridians and rescue of the interior. This distinguishes three conditions within the Sinking pulse: Hidden Pathogen, Righteous Deficiency, and Yin-Cold. The Sinking pulse of a Yin syndrome is Sinking, Slow, and distinct. The Sinking pulse of a Hidden Pathogen is Sinking, Hidden, Rapid, and blurred. The Micro pulse of Righteous Deficiency is regardless of Floating or Sinking, appearing weak and powerless upon prolonged pressing. Therefore, Slow and distinct pulses indicate interior cold. Sinking and Hidden pulses indicate that exterior pathogens cannot be vented. A Micro pulse in a Yang syndrome indicates excessive pathogen and deficient righteous Qi. Now, if there are symptoms of Yang pathogens but a Sinking-Hidden pulse appears, mistaking it for a Yin syndrome and using warm-hot herbs will cause internal eruption of Yang pathogens, leading to rapid death. If irritability and restlessness are seen and cold-cooling herbs are mistakenly used, it will suppress the release of exterior sweat. Thus, the principle of pulse diagnosis is to first distinguish the syndrome, and then deliberate based on the pulse. A Sinking pulse indicates purgation is needed; if the exterior syndrome is urgent, the exterior should still be dispersed first. A Floating pulse indicates sweating is needed; if there is interior heat, resolving both exterior and interior is necessary. If the purgation syndrome is urgent, dual resolution of exterior and interior is unavoidable.