春甫谨按∶望闻问切四字，诚为医之纲领，若得四字之旨，则于医学可谓至矣。今人惟问一
端而已，其于望闻亦浅浅耳。至于切脉，则又谓居三者之末而犹后轻视之，故所以卒鲜有精于脉
者。间有言者，亦不过左心小肠之说耳。经位不别，其何以察虚实生死之几耶？殊不知四者之要，
则又在乎切之之功也，其望其闻其问之三者，先以得其病情之端，而后总切脉于寸口，确乎知始
病之源。而方今延流于何脏何经、若虚若实、或死或生，准候酌方，必有赖于切脉而后可以为图
治之效矣。斯其次第之序，初近患人，光望而闻，次问而切，固理之不容易也。然则切脉果可轻
与？予故订之，以备知者之取采耳。
黄帝问于岐伯曰∶余闻之，见其色知其病，命曰明；接其脉知其病，命曰神；问其病知其处，
命曰工。余愿闻见而知之，按而得之，问而极之，为之奈何？岐伯曰∶夫色脉与尺脉之相应也，
如桴鼓影响之相应也，不得相失也。此亦本末根叶之出候也，故根死则叶枯矣。色脉形肉不得相
失也，故知一则为二，知二则为神，知三则神且明矣。
又曰∶望而知之谓之神，闻而知之谓之圣，问而知之谓之工，切脉而知之谓之巧。
六十一难曰∶望而知之者，望见五色，以知其病之所处也；闻而知之者，闻其五音，以别其
病之所出也；问而知之者，间其所欲五味，以知其病之所起所在也；切脉而知之者，诊其寸口，
视其虚实，以知其病在何脏腑也。
徐春甫谨慎地按语道：望、闻、问、切这四个字，确实是医学的纲领。如果能掌握这四个字的精髓，那么对于医学可以说已经达到极致了。现在的人只注重问诊这一方面，而对于望诊和闻诊也只是肤浅地了解罢了。至于切脉，人们又认为它居于三者之后而轻视它，所以最终很少有精通脉学的人。偶尔有人谈论脉学，也不过是左心与小肠相表里的说法而已。如果不区分经脉的位置，又怎么能察知虚实生死的关键呢？殊不知四诊的要领，其实关键在于切脉的功效。望、闻、问这三者，先用来获取病情的端倪，然后综合在寸口处切脉，从而确切地知道疾病最初的根源。而如今病情流传到哪个脏腑、哪条经络，是虚还是实，或者生或者死，根据脉象斟酌处方，一定依赖于切脉才能制定治疗的有效方案。这其中的次序顺序，初近患者时，首先观察并听嗅，其次询问并切脉，这确实是不可更改的道理。那么切脉果真可以轻视吗？所以我对此进行订正，以备有识之士采纳。
黄帝向岐伯问道：我听说，通过观察面色就知道疾病，称为“明”；通过接触脉搏就知道疾病，称为“神”；通过询问病情就知道病位，称为“工”。我希望了解如何通过观察而知晓、通过按压（切脉）而获得、通过询问而穷尽的方法，该怎么做呢？岐伯回答说：面色、脉象与尺肤脉之间的相应关系，就像鼓槌敲击鼓面、声音产生回响那样相互对应，不会失去联系。这也是本末根叶所呈现的征候，所以如果根部死亡，叶子就会枯萎。面色、脉象、形体和肌肉之间不能失去相应的联系，所以懂得其中一项就能达到两项的水平，懂得两项就能达到神的境界，懂得三项就既神且明了。
又说：通过望诊就能知晓病情称为“神”，通过闻诊就能知晓病情称为“圣”，通过问诊就能知晓病情称为“工”，通过切脉就能知晓病情称为“巧”。
《难经·六十一难》说：通过望诊就能知晓病情的人，是观察五色，从而知道疾病所在的位置；通过闻诊就能知晓病情的人，是听取五音，从而辨别疾病产生的来源；通过问诊就能知晓病情的人，是询问病人对五味（酸苦甘辛咸）的欲望，从而知道疾病的起因和所在部位；通过切脉就能知晓病情的人，是诊察寸口脉，观察其虚实，从而知道疾病在哪个脏腑。
Xu Chunfu cautiously remarks: The four characters of Wang (Observation), Wen (Listening and Smelling), Wen (Inquiry), and Qie (Palpation) are indeed the guiding principles of medicine. If one grasps the essence of these four, one can be said to have reached the pinnacle of medical knowledge. Nowadays, people only focus on Inquiry, while their understanding of Observation and Listening/Smelling is superficial. As for Palpation, it is often considered inferior to the other three and thus neglected; consequently, few people become proficient in pulse diagnosis. Those who occasionally discuss pulse diagnosis merely refer to the theory that the Heart and Small Intestine are exteriorly-interiorly related. Without distinguishing the positions of the meridians, how can one discern the critical signs of deficiency, excess, life, and death? It is unknown to many that the key to the four diagnostic methods lies in the efficacy of Palpation. Observation, Listening/Smelling, and Inquiry first provide clues to the patient's condition, after which palpating the Cun Kou (Radial Artery at the wrist) allows one to accurately determine the original source of the disease. In current practice, to determine which Zang-Fu organ or meridian is affected, whether the condition is deficient or excess, and whether the prognosis is life or death, prescribing treatment relies heavily on pulse diagnosis to achieve therapeutic effectiveness. This sequence—initially observing and listening/smelling, then inquiring and palpating—is an unchangeable principle. Can Palpation truly be neglected? Therefore, I have revised this topic for the reference of knowledgeable practitioners.
The Yellow Emperor asked Qibo: I have heard that recognizing a disease by observing facial color is called "Ming" (Clear); recognizing a disease by feeling the pulse is called "Shen" (Divine); recognizing the location of a disease by inquiry is called "Gong" (Skilled). I wish to know how to achieve knowledge through observation, acquisition through palpation, and thoroughness through inquiry. How should this be done? Qibo replied: The correspondence between facial color, pulse, and Chi Fu (forearm skin) pulse is like the response of a drumstick to a drum or the echo to a sound; they must not be disconnected. This is also the manifestation of the root and branches, or trunk and leaves; if the root dies, the leaves wither. Facial color, pulse, body form, and flesh must not lose their correspondence. Knowing one aspect leads to knowing two; knowing two aspects leads to the state of Shen (Divine); knowing all three aspects results in being both Shen and Ming.
It is also said: Recognizing disease through Observation is called "Shen" (Divine); recognizing disease through Listening/Smelling is called "Sheng" (Sage); recognizing disease through Inquiry is called "Gong" (Skilled); recognizing disease through Palpation is called "Qiao" (Skillful).
Chapter 61 of the Nan Jing (Classic of Difficult Issues) states: One who knows disease through Observation sees the five colors and thereby knows the location of the disease; one who knows disease through Listening/Smelling hears the five tones and thereby distinguishes the origin of the disease; one who knows disease through Inquiry asks about desires for the five flavors (sour, bitter, sweet, pungent, salty) and thereby knows the cause and location of the disease; one who knows disease through Palpation examines the Cun Kou (Radial Pulse) and observes its deficiency or excess to know which Zang-Fu organ is diseased.