丹溪曰∶西北之地多风寒，故患外感者居多；东南之地本卑湿，故患湿热者众。盖北方高阜，
天不足西北而多风；南方卑下，地不满东南而多湿。所以方土之候，各有不齐，而所生之病，多
随土着。医者必须因时处治，随地判宜。治北人之病，宜以攻伐外邪为多；治南方之疾，宜以保
养内气为本。何则？北方风气浑浓，禀赋雄壮，兼之饮食倍常，居室俭素，殊少戕贼元气之患，
一有疾病，辄以疏利之，其病如脱而快意通神矣。若夫东南之人，体质柔脆，腠理不密，而饮食
色欲之过侈，与西北之人迥异，概以峻剂攻之，不几操刃而杀人乎？虽然，北方禀气固浓，安能
人人皆实？南方禀气虽薄，安得人人皆虚？当观其人，因其证而施药之，斯无一偏之弊矣。
皇甫谧《黄帝世纪》曰∶黄帝命雷公岐伯教别九针，着《内外经》、《素问》，书咸出焉。
《黄帝内传》曰∶帝升为天子，《针经》、《脉诀》无不备也，故《金匮》、《甲乙》之书皆祖《内经》。
黄帝御极，坐明堂之上，临观八极，考建五常，以谓人生负阴而抱阳，食味而被色，寒暑相
荡，喜怒交伤，乃与岐伯上穷天纪，下极地理，远取诸物，近取诸身，更相问难。雷公之伦，授
业传之，而《内经》作矣。
苍周之兴，秦和述六气之论，具于左史。厥后越人得其一二，演述《难经》，西汉仓公传其旧业，
东汉仲景撰其遗论，晋皇甫谧刺为《甲乙》，隋杨上善纂为《太素》，唐王冰笃好之，大为次注。
（林亿《素问序》）
《内经素问》，世称黄帝岐伯问答之书，及观其旨意，殆非一时之言，其所撰述，亦非一人
之手。刘向指为诸韩公子所着，程子谓出于战国之末。而其大略，正如《礼记》之萃于汉儒，而
与孔子子思之言并传也。盖灵兰秘典、五常政、六元正纪等篇，无非阐明阴阳五行生制之理，配
象合德，实切于人身。其诸色脉、病名、针刺、治要，皆推是理以广之。皇甫谧之《甲乙》，杨
上善之《太素》，亦皆本之于此。按西汉《艺文志》有《内经》十八卷之目，至隋《经籍志》始
有《素问》之名，而不指为《内经》。唐王冰乃以《灵枢》九卷率合《汉志》之数，而为之注释，
后以《阴阳大论》托其为师张公所藏，以补其亡逸，其用心亦勤矣。惜乎朱墨混淆，玉石相乱，
训诂失之于迂疏，援引或至于未切。至宋林亿、高若讷等正其误文而精其缺义，颇于冰为有功。（《医史》）
Zhu Danxi said: In the northwest regions, the climate is predominantly cold and windy; therefore, exogenous diseases (diseases caused by external pathogenic factors) are common. In the southeast regions, the land is naturally low and damp; consequently, damp-heat (a pathological condition characterized by dampness and heat pathogens) disorders are prevalent. Generally speaking, the north features high terrain where heavenly yang energy is deficient in the northwest, leading to much wind; the south features low terrain where earthly yin energy is insufficient in the southeast, leading to much dampness. Thus, climatic conditions vary by locality, and diseases arising there tend to follow local environmental habits. Physicians must formulate treatments according to the season and judge appropriateness based on the region. When treating patients from the north, it is appropriate to focus more on attacking and dispelling exogenous pathogens; when treating illnesses in the south, it is appropriate to prioritize preserving and nourishing internal qi (vital energy). Why? The northern atmosphere is dense, and people possess robust constitutions due to their innate endowment. Coupled with diets exceeding normal quantities and frugal living conditions, they rarely suffer from damage to their yuan qi (original vital energy). Once illness occurs, using methods of unblocking and purging often leads to rapid recovery, bringing relief and mental clarity. Conversely, people from the southeast have fragile constitutions and loose cou li (skin texture and interstices/pores). Their indulgence in diet and sexual desire differs vastly from those in the northwest. If one were to uniformly apply harsh or drastic formulas to attack pathogens, would it not be akin to killing someone with a blade? Nevertheless, although northerners generally possess strong innate qi, can everyone be considered solid/excess? Although southerners generally possess thin/weak innate qi, can everyone be considered deficient? One must observe the individual patient and administer medicine according to their specific syndrome differentiation (pattern identification), thereby avoiding the弊端 of bias.
Huangfu Mi, in *The Century of the Yellow Emperor*, stated: The Yellow Emperor ordered Leigong and Qibo to teach the distinction of the Nine Needles, composing the *Nei Wai Jing* (Classic of Internal and External Medicine) and *Su Wen* (Basic Questions); these texts originated from this instruction.
*The Inner Biography of the Yellow Emperor* states: After ascending the throne as Son of Heaven, the *Jing Jing* (Classic of Acupuncture) and *Mai Jue* (Pulse Secrets) were all complete. Therefore, works such as *Jin Gui Yao Lue* (Essential Prescriptions of the Golden Cabinet) and *Zhen Jiu Jia Yi Jing* (Acupuncture and Moxibustion: A Systematic Classic) trace their ancestry back to the *Nei Jing* (Inner Canon).
When the Yellow Emperor assumed imperial power, he sat in the Bright Hall, observing the eight extreme directions, investigating and establishing the Five Constants (benevolence, righteousness, propriety, wisdom, and trustworthiness). He reasoned that human life carries yin and embraces yang, tastes flavors, and encounters beauty, while cold and heat interact and anger and joy alternately cause harm. Thus, he engaged in mutual questioning and difficulty resolution with Qibo, exploring heaven's laws to the utmost extent above, earth's geography to the utmost extent below, taking examples from distant objects, and taking references from the body itself. Disciples like Leigong received this teaching and transmitted it, resulting in the creation of the *Nei Jing*.
During the rise of the Zhou dynasty, Qin Yueren (Bian Que) expounded on the theory of the Six Qi (wind, cold, summer heat, dampness, dryness, fire), which was recorded in detail by left historians. Later, Yueren grasped some of its principles and elaborated upon them in the *Nan Jing* (Classic of Difficult Issues). Cang Gong (Chunyu Yi) of the Western Han inherited this tradition. Zhang Zhongjing of the Eastern Han compiled his remaining theories into writings. Huangfu Mi of the Jin Dynasty edited these into the *Zhen Jiu Jia Yi Jing*. Yang Shangshan of the Sui Dynasty compiled them into the *Huang Di Nei Jing Tai Su*. Wang Bing of the Tang Dynasty held a deep affection for these texts and extensively revised and annotated them. (From Lin Yi's Preface to *Su Wen*)
The *Su Wen* section of the *Nei Jing* is widely known as a book of dialogues between the Yellow Emperor and Qibo. However, examining its intent, it seems unlikely that it consists of words spoken at a single time, nor was it written by a single hand. Liu Xiang pointed out that it was authored by princes of various states of Han. Cheng Zi (Cheng Hao or Cheng Yi) suggested it originated from the late Warring States period. Its general nature is similar to how the *Li Ji* (Book of Rites) was compiled by Han Confucians, yet transmitted alongside the words of Confucius and Zisi. Chapters such as *Ling Lan Mi Dian Lun*, *Wu Chang Zheng Da Lun*, and *Liu Yuan Zheng Ji Da Lun* essentially elucidate the principles of generation and restriction among Yin-Yang and the Five Elements, aligning images with virtues, and are indeed pertinent to the human body. Various aspects regarding complexion observation, pulse diagnosis, disease names, acupuncture, and treatment essentials all expand upon these principles. Huangfu Mi’s *Zhen Jiu Jia Yi Jing* and Yang Shangshan’s *Tai Su* are also based on this foundation. According to the *Yi Wen Zhi* (Treatise on Literature) of the Western Han, there was a title for *Nei Jing* comprising eighteen volumes. It was not until the *Jing Ji Zhi* (Treatise on Books and Records) of the Sui Dynasty that the name *Su Wen* appeared, without being explicitly identified as the *Nei Jing*. Wang Bing of the Tang Dynasty then combined the nine volumes of *Ling Shu* (Spiritual Pivot) to match the count in the *Han Zhi*, providing annotations for them. Later, he attributed the *Yin Yang Da Lun* to his teacher Master Zhang’s collection to supplement lost content, showing considerable diligence. Unfortunately, red and black ink marks became confused, jade and stones were mixed, glosses were pedantic and loose, and citations were sometimes imprecise. It was not until the Song Dynasty, when Lin Yi, Gao Ruone, and others corrected erroneous texts and refined missing meanings, that merit was truly achieved relative to Wang Bing. (From *History of Medicine*)