尝思一阴一阳，互为之根，天地之气化也。人禀天地之气化以生，即人身各具一小天地，其气化何独
不然。是以人之全身，阴阳互相维系，上焦之阳藏于心中血，中焦之阳涵于胃液，下焦之阳存于肾水，凡心
血、胃液、肾水皆阴也。充类言之，凡全身津液脂膏脉腺存在之处，即元阳留蓄之处。阳无阴则飞越，阴无
阳则凝滞。阳盛于阴则热，阴盛于阳则冷。由斯知阴阳偏盛则人病，阴阳平均则人安，阴阳相维则人生，阴
阳相离则人死。彼为贵阳抑阴之论者，竟谓阳一分未尽则人不死，阴一分未尽则人不仙，斯何异梦中说梦也。
然此则论未病之时，阴阳关于人身之紧要，原无轩 也。若论已病，又恒阳常有余，阴常不足（朱丹溪曾有此论）。
医者当调其阴阳，使之归于和平，或滋阴以化阳，或泻阳以保阴，其宜如此治者，又恒居十之八九。倘曰
不然，试即诸病征之。
病有内伤外感之殊，而外感实居三分之二。今先以外感言之，伤寒、温病、疫病皆外感也，而伤寒中于
阴经，宜用热药者，百中无二三也；温病则纯乎温热，已无他议；疫病虽间有寒疫，亦百中之一二也。他
如或疟，或疹，或痧证，或霍乱，亦皆热者居多，而暑 之病更无论矣。
试再以内伤言之。内伤之病，虚劳者居其半，而劳字从火，
其人大抵皆阴虚阳盛，究之亦非真阳盛，乃阴独虚致阳偏盛耳。他如或吐衄，或淋痢，或肺病、喉病、眼疾，
或黄胆，或水病、肿胀、二便不利，或嗽，或喘，或各种疮毒，以上诸证，已为内伤之大凡，而阳盛阴虚者
实为十之八九也。世之业医者，能无于临证之际，以急急保其真阴为先务乎？即其病真属阳虚，当用补
阳之药者，亦宜少佐以滋阴之品；盖上焦阴分不虚而后可受参、 ，下焦阴分不虚而后可受桂、附也。
我曾思考，阴与阳互为根本，这是天地气化的规律。人禀受天地的气化而生，人身便各自具备一个小天地，其气化规律为何唯独不同呢？因此，人的全身阴阳互相维系：上焦的阳气藏纳于心中的血液里，中焦的阳气涵育于胃液之中，下焦的阳气存留于肾水之内，凡是心血、胃液、肾水都属于阴。推而广之，凡全身津液、脂膏、脉管、腺体存在的地方，就是元阳（人体最根本的阳气）蓄积的地方。阳气如果没有阴作为根基就会飞散越出，阴气如果没有阳的推动就会凝滞不通。阳气偏盛于阴则发热，阴气偏盛于阳则发冷。由此可知，阴阳偏盛则人生病，阴阳平衡则人安康，阴阳相互维系则人存活，阴阳分离则人死亡。那些主张“贵阳抑阴”的人，竟然说阳气一分未尽人就不会死，阴气一分未尽人就不能成仙，这跟梦中说梦有什么区别呢？然而，这是在讨论未患病时，阴阳对于人身的重要性，原本没有高下之分。如果讨论已患病的情况，又常常是阳气常有余，阴气常不足（朱丹溪曾有此观点）。医生应当调理阴阳，使其归于平和，或者通过滋阴来化生阳气，或者通过泻除阳热来保全阴液，适宜这样治疗的病例，往往占十之八九。如果说不是这样，不妨用各种病症来验证。
疾病有内伤和外感的不同，而外感病实际上占三分之二。现在先以外感病来说，伤寒、温病、疫病都属于外感病，而在伤寒中侵犯阴经、适宜使用热性药物的，百人中不到两三个；温病则完全是温热性质，已无其他争议；疫病虽然偶尔有寒疫，但也只占一二成。其他的如疟疾、疹病、痧证、霍乱等，也都以热证居多，至于暑邪致病就更不用说了。
再以内伤病来说。内伤病中，虚劳病占一半，而“劳”字从火，这类病人大多阴虚阳盛，究其根本也不是真正的阳气旺盛，而是由于阴单独虚弱导致阳气相对偏盛罢了。其他的如吐血、衄血、淋证、痢疾、肺病、喉病、眼疾、黄疸、水肿、肿胀、大小便不利、咳嗽、气喘以及各种疮毒等，以上这些症状，已经是内伤病的大致情况，其中属于阳盛阴虚的确实占了十之八九。世间的行医之人，难道在临证时不把急切地保护真阴作为首要任务吗？即使病人的病证确实属于阳虚，应当使用补阳药物时，也应当少量佐以滋阴的药物；因为上焦阴分不虚，之后才能承受人参、黄芪的补益；下焦阴分不虚，之后才能承受肉桂、附子的温燥。
I have pondered that Yin and Yang are mutually rooted, which is the law of Qi transformation in Heaven and Earth. Humans are born by inheriting the Qi transformation of Heaven and Earth; thus, each human body constitutes a small Heaven and Earth. Why should its Qi transformation be any different? Therefore, Yin and Yang in the whole body maintain each other: the Yang Qi of the Upper Jiao (Upper Burner) is stored in the blood of the Heart; the Yang Qi of the Middle Jiao (Middle Burner) is contained within the Stomach fluids; and the Yang Qi of the Lower Jiao (Lower Burner) resides in the Kidney water. All these—Heart blood, Stomach fluids, and Kidney water—are Yin. Extending this logic, wherever fluids, fats, vessels, and glands exist in the whole body, there the Primordial Yang (Yuan Yang, the most fundamental Yang Qi of the body) is accumulated. Without Yin, Yang will fly away and scatter; without Yang, Yin will stagnate and coagulate. When Yang prevails over Yin, heat occurs; when Yin prevails over Yang, cold occurs. From this, we know that when Yin and Yang are imbalanced, disease arises; when they are balanced, health prevails; when they mutually sustain each other, life continues; and when they separate, death ensues. Those who advocate the theory of "valuing Yang and suppressing Yin" claim that as long as even a fraction of Yang remains, one does not die, and as long as even a fraction of Yin remains, one cannot become an immortal. How is this different from dreaming within a dream? However, this discussion pertains to the state before illness, where Yin and Yang are equally crucial to the human body, with no superiority or inferiority between them. But when discussing existing illness, it is often the case that Yang is constantly in excess and Yin is constantly deficient (a view previously held by Zhu Danxi). Physicians should regulate Yin and Yang to restore harmony, either by nourishing Yin to transform Yang, or by purging Yang to preserve Yin. Such treatments account for nine out of ten cases. If one claims otherwise, let us verify this against various diseases.
Diseases differ into internal injury and external contraction, with external contractions accounting for two-thirds. Let us first discuss external contractions. Shanghan (Cold Damage), Wenbing (Warm Diseases), and epidemics all belong to external contractions. Among Shanghan cases, those attacking the Yin meridians and suitable for hot medicines are fewer than two or three in a hundred; Wenbing is purely warm-heat in nature, leaving no room for debate; although epidemics occasionally include cold epidemics, they constitute only one or two in a hundred. Other conditions such as malaria, rashes, sha syndrome (sand poisoning), and cholera are also predominantly heat-related, while diseases caused by summer-heat are even more so.
Let us further discuss internal injuries. Among internal injuries, consumptive diseases (Xu Lao) account for half. The character for "consumption" (Lao) contains the radical for fire; thus, such patients generally suffer from Yin deficiency and Yang excess. Ultimately, this is not true Yang excess, but rather Yang appearing excessive due to isolated Yin deficiency. Other conditions such as hematemesis (vomiting blood), epistaxis (nosebleed), stranguria (dysuria), dysentery, lung diseases, throat diseases, eye disorders, jaundice, edema, swelling, difficulty in urination and defecation, cough, asthma, and various toxic sores represent the general scope of internal injuries, among which Yin deficiency and Yang excess indeed account for nine out of ten. Do physicians in the world not consider urgently preserving True Yin as their primary task during clinical practice? Even if the disease truly belongs to Yang deficiency and requires Yang-tonifying medicines, it is still appropriate to add a small amount of Yin-nourishing herbs; because only when the Yin aspect of the Upper Jiao is not deficient can it tolerate the tonification of Ginseng Radix et Rhizoma (Renshen) and Astragali Radix (Huangqi); and only when the Yin aspect of the Lower Jiao is not deficient can it tolerate the warming properties of Cinnamomi Ramulus (Guizhi) and Aconiti Lateralis Radix Praeparata (Fuzi).