夫病生之类，其有四焉∶一者，始因气动而内有所成；二者，始因气动而外有所成；三者，
不因气动而病生于内；四者，不因气动而病生于外。
夫因气动而内成者，谓积聚、 瘕、瘤气、瘿起、结核、癞痫之类是也。
外成者，谓痈肿疮疡，痂疥疽痔，掉 浮肿，目赤瘭胗，腑肿痛痒之类也。
不因气动而病生于内者，谓留饮、 食、饥饱、劳损、宿食、霍乱、悲恐、喜怒、想慕、忧结之类。
不因气动而病生于外者，谓瘴气、贼魅、虫蛇、蛊毒、蜚食、鬼击、冲薄、坠
堕、风寒、暑湿、斫射、刺割、挞朴之类也。如此四类，有独治内而愈者，有兼治内而愈者；有独治外
而愈者；有兼治外而愈者；有先治内后治外而愈者；有先治外后治内而愈者；有须解毒而攻
击者，有须无毒而调引者。凡此之类，方法所施，或重或轻，或缓或急，或收或散，或润或
燥，或软或坚。方士之用，见解不同，各擅己心，好丹非素，故复问之。
五苦六辛，从来无解，盖史家阙其疑也。一日，麻征君以此质疑于张先生。先生亦无所应。
行十五里，忽然有所悟，欣然回告于麻征君。以为五苦者，五脏为里属阴，宜用苦剂，谓酸
苦涌泄为阴；六辛者，六腑为表属阳，宜用辛剂，谓辛甘发散为阳。此其义也。征君大服其
识见深远，凿昔人不传之妙。故曰知其要者，一言而终；不知其要者，流散无穷。
疾病的产生，大致有四种情况：第一，起初因气机运动而在体内形成病变；第二，起初因气机运动而在体表形成病变；第三，不因气机运动而病生于体内；第四，不因气机运动而病生于体外。
所谓因气机运动而在体内形成的病变，是指积聚、瘕（腹中结块）、瘤气、瘿起（颈部肿块）、结核（皮下结节）、癞痫等病症。
所谓在体表形成的病变，是指痈肿疮疡、痂疥疽痔、掉眩浮肿、目赤瘭胗（眼部红肿及皮肤疱疹）、腑肿痛痒等病症。
所谓不因气机运动而病生于体内的，是指留饮（水液停聚）、饮食失调、饥饱失常、劳损、宿食、霍乱、悲恐、喜怒、想慕（思虑过度）、忧结等病因。
所谓不因气机运动而病生于体外的，是指瘴气、贼魅（邪祟）、虫蛇咬伤、蛊毒、蜚食（飞虫蚀人）、鬼击、冲薄（撞击挤压）、坠堕、风寒、暑湿、斫射（刀砍箭射）、刺割、挞朴（鞭打杖击）等病因。
像这四种情况，有的只需治疗内部就能痊愈，有的需内外兼治才能痊愈；有的只需治疗外部就能痊愈；有的需内外兼治才能痊愈；有的先治内后治外才能痊愈；有的先治外后治内才能痊愈；有的需要解毒并攻逐邪气，有的则需要无毒药物进行调理引导。凡此种种，治疗方法的应用，有的重剂，有的轻剂，有的缓治，有的急治，有的收敛，有的发散，有的滋润，有的燥湿，有的软坚，有的硬散。方士们用药，见解不同，各自依从自己的心意，喜好红色（丹）而轻视白色（素），因此对此再次加以探讨。
“五苦六辛”这一说法，历来没有人解释清楚，大概是史书作者对存疑之处予以省略。有一天，麻征君带着这个疑问向张先生请教。先生当时也没有回应。走了十五里路后，先生忽然有所领悟，高兴地回来告诉麻征君。他认为“五苦”，是指五脏位于体内属阴，适宜使用苦味药，即酸苦涌泄属于阴的性质；“六辛”，是指六腑位于体表属阳，适宜使用辛味药，即辛甘发散属于阳的性质。这就是其中的道理。征君非常佩服他的见识深远，认为他阐明了前人未曾传授的奥妙。所以说，懂得关键的人，一句话就能终结疑惑；不懂关键的人，就会流散无穷无尽。
The origins of disease can be categorized into four types: First, lesions originate internally due to the movement of Qi; Second, lesions manifest externally due to the movement of Qi; Third, diseases arise internally independent of Qi movement; Fourth, diseases arise externally independent of Qi movement.
Those originating internally due to Qi movement refer to conditions such as Ji Ju (accumulations and masses), Xia (abdominal masses with shifting pain), Liu Qi (tumor-like Qi stagnation), Ying Qi (goiter or neck masses), He Jie (scrofula or subcutaneous nodules), and Lei Xian (leprosy and epilepsy).
Those manifesting externally refer to conditions such as Yong Zhong Chuang Yang (carbuncles, swellings, sores, and ulcers), Jia Jie Ju Zhi (scabs, scabies, carbuncles, and hemorrhoids), Diao Xuan Fu Zhong (dizziness and edema), Mu Chi Biao Zhen (red eyes and skin blisters/rashes), and Fu Zhong Tong Yang (visceral swelling, pain, and itching).
Those arising internally independent of Qi movement include causes such as Liu Yin (retained fluid/drink), dietary irregularities, hunger and satiety imbalances, physical exhaustion, Su Shi (retained food), Huo Luan (cholera-like vomiting and diarrhea), emotional factors like Bei Kong (sorrow and fear) and Xi Nu (joy and anger), Xiang Mu (obsessive longing), and You Jie (depressive stagnation).
Those arising externally independent of Qi movement include environmental and external pathogens such as Zhang Qi (miasma), Zei Mei (evil spirits/pestilence), Chong She (insect and snake bites), Gu Du (gu poison), Fei Shi (flying insects causing harm), Gui Ji (ghost strikes), Chong Bo (blunt trauma/crushing), Zhui Duo (falls), Feng Han (wind-cold), Shu Shi (summerheat-dampness), Zhuo She (cuts from blades and arrows), Ci Ge (punctures and lacerations), and Ta Pu (beatings with whips and sticks).
Regarding these four categories, some are cured by treating only the interior, while others require simultaneous treatment of both interior and exterior; some are cured by treating only the exterior, while others require combined treatment; some are cured by treating the interior first and then the exterior, while others are cured by treating the exterior first and then the interior; some require detoxification and attacking methods, while others require non-toxic herbs for regulation and guidance. In applying these methods, treatments may be heavy or light, slow or rapid, astringent or dispersing, moistening or drying, softening or hardening. Practitioners differ in their understanding and application, each relying on their own judgment, favoring certain approaches over others, which necessitates further inquiry.
The concept of "Wu Ku Liu Xin" (Five Bitters and Six Pungents) has never been adequately explained, likely because historians omitted it as uncertain. One day, Zhengjun Ma posed this question to Mr. Zhang. Initially, Mr. Zhang had no answer. After walking fifteen li, he suddenly gained insight and joyfully returned to explain it to Zhengjun Ma. He reasoned that "Wu Ku" (Five Bitters) refers to the Five Zang Organs being internal and Yin in nature, thus suitable for bitter substances, aligning with the principle that sour and bitter induce vomiting and purging, which are Yin actions. "Liu Xin" (Six Pungents) refers to the Six Fu Organs being external and Yang in nature, thus suitable for pungent substances, aligning with the principle that pungent and sweet substances disperse and ascend, which are Yang actions. This is the underlying logic. Zhengjun Ma greatly admired his profound insight, considering it to have uncovered the hidden mysteries not transmitted by ancients. Thus it is said: "He who knows the essence needs but one word to conclude; he who does not know the essence wanders endlessly."