内经云。太阳之胜。火气内郁。流散于外。足 肿。饮发于中。 肿于上。又云。脾脉搏坚
而长。其色黄。当病少气。其 而散色不泽者。当病足 肿。若水状也。脾病者、身重肉痿。足不
能行。善 。脚下痛。此谷入多而气少。湿居下也。故湿从下受之。如上所说。皆谓脾胃湿气下流
。乘其肝肾之位。由是足胫疼痛而 肿也。夫五谷入胃。糟粕、津液、宗气。分为三隧。故宗气积
于胸中。出于喉咙。以贯心肺而行呼吸焉。营气者秘其津液。注之于脉。化而为血。以营四末。内
注五脏六腑。以应刻数焉。卫气者。出悍气之 疾。而先行于四末分肉之间。行而不休者也。又宗
气之道。内谷为实。谷入于胃。乃传之于脉。流溢于中。布散于外。精专者行于经隧。常营无已。
终而复始。是谓天地之纪。或饮食失常。胃气不能鼓舞。脾气不能运化。行于百脉。其气下流。乘
其肝肾。土木水相合。下疰于足 。 肿而作疼痛。晋苏敬号为香港脚是也。凡治此疾。每旦早饭。
任意饱食。午饭少食。日晚不食。弥佳。恐伤脾胃营运之气。失其天度。况夜食则血气壅滞。而行
阴道。愈增肿痛。古之人少有此疾。自永嘉南渡。衣缨士人多有之。大唐开关。爪牙之士作镇于南
极。其地卑湿。雾露所聚。不袭水土。往者皆遭之。关西河北人。皆不生此疾。外台秘要总录。亦
说江东岭南大率有此。此盖清湿袭虚伤于下。故经云。感则害人皮肉筋骨者也。故制方立论。皆详
其当时土地所宜而治之。今观此方爽
恺。（谓爽明恺燥也。本左传）而无卑湿之地。况腠理致密。外邪难侵。而有此疾者。何也。盖
多饮乳酪醇酒。水湿之属也。加以奉养过度。以滋其湿水之润下。气不能 之。故下疰于足 。积
久而作肿满疼痛。此饮之下流之所致也。岂可与南方之地同法而治哉。当察其地势高下。详其饮食
居处。立为二法。一则治地之湿气。一则治饮食之下流。随其气宜。用药施治。使无疾之苦。庶几
合轩岐之旨哉。孙真人云。医者、意也。随时增损。物无定方。真知言哉。
《黄帝内经》说：太阳之气偏胜，火气在体内郁结，流散于体表。足部肿胀，水饮发于中焦，头面浮肿于上。又说：脾脉搏动坚实而长，面色发黄，应当患少气病；若脉象散乱、面色无光泽，应当患足胫肿胀，状如水病。脾脏患病的人，身体沉重，肌肉痿软，脚不能行走，容易腹泻，脚下疼痛。这是因为饮食摄入多但正气不足，湿气居于下部。所以湿气是从下部受邪的。如上所述，都是指脾胃湿气下流，乘袭肝肾之位，从而导致足胫疼痛和肿胀。
五谷进入胃中，糟粕、津液、宗气分为三条通道。所以宗气积聚于胸中，出于喉咙，贯通心肺以主持呼吸。营气秘藏其津液，注入脉中，化生为血液，以营养四肢末端，内注五脏六腑，以应合刻漏计时（气血运行规律）。卫气是出于悍气的疾速部分，先行于四肢分肉之间，运行不休止。另外，宗气的运行之道，以内谷为充实基础。谷物进入胃中，便传之于脉，流溢于中，布散于外。精纯专一的部分行于经脉隧道，常营运不止，终而复始，这称为天地运行的纲纪。
如果饮食失常，胃气不能鼓舞，脾气不能运化，气行于百脉时向下流注，乘袭肝肾，土、木、水三者相合，湿气下注于足胫，导致肿胀并产生疼痛。晋代苏敬称之为“香港脚”。凡是治疗这种疾病，每天早饭可以任意吃饱，午饭少吃，晚上不吃，这样更好。恐怕损伤脾胃营运之气，违背自然规律。况且夜间进食则血气壅滞，而行阴道，更加增加肿痛。古代人很少患此病，自从永嘉南渡以来，士大夫阶层人多有此病。大唐开国后，武将镇守南方极远之地，那里地势低洼潮湿，雾露聚集，不习惯当地水土的人前往都会遭受此病困扰。关西、河北地区的人，都不生此病。《外台秘要》总录也说，江东、岭南地区大体都有此病。这大概是清湿侵袭虚弱部位伤于下部，所以经文说：“感邪则伤害人的皮肉筋骨。”因此制定方剂和立论，都详细考察当时当地土地适宜的情况来治疗。
现在观察此地（北方）爽朗干燥，没有卑湿之地，况且腠理致密，外邪难以侵入，却还有患此病的人，为什么呢？大概是因为多饮用乳酪醇酒，这些属于水湿之物。加上供养过度，助长了湿水的润下特性，阳气不能制约它，所以下注于足胫，积久导致肿胀满痛。这是饮食之下流所致。怎么能与南方之地用同样的方法治疗呢？应当考察地势的高下，详细询问饮食居处情况，确立两种治法：一则治疗地之湿气，一则治疗饮食之下流。随其气宜，用药施治，使患者免除疾病痛苦，这才符合轩辕、岐伯的宗旨吧。孙思邈真人说：医者，意也。随时增减损益，药物没有固定的方剂。真是知言啊。
The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: When the Taiyang (Greater Yang) qi prevails, fire qi is internally constrained and flows outward to the exterior. The feet swell; fluid retention originates in the middle jiao, causing edema of the head and face. It also states: If the Spleen pulse is firm and long, and the complexion is yellow, one should suffer from shortness of breath (Shaoqi). If the pulse is scattered and the complexion lacks luster, one should suffer from swelling of the lower legs and shins, resembling water disease. In diseases of the Spleen, the body feels heavy, muscles are flaccid and atrophic, the feet cannot walk, diarrhea is frequent, and there is pain under the feet. This occurs because food intake is abundant but qi is deficient, and dampness resides in the lower part. Therefore, dampness enters from below. As mentioned above, this refers to dampness from the Spleen and Stomach flowing downward, attacking the positions of the Liver and Kidney, thereby causing pain and swelling in the lower legs and shins.
When five grains enter the Stomach, dregs, body fluids, and Zong Qi (Gathering Qi) are divided into three pathways. Thus, Zong Qi accumulates in the chest, emerges from the throat, penetrates the Heart and Lungs, and governs respiration. Ying Qi (Nutritive Qi) retains its fluids, injects them into the vessels, transforms into blood, and nourishes the four extremities, internally supplying the Five Zang and Six Fu organs to correspond with the rhythmic flow of time (Ke Shu). Wei Qi (Defensive Qi), derived from the rapid aspect of Han Qi (Pugnacious Qi), moves swiftly ahead between the muscles and skin of the four extremities, moving without rest. Furthermore, the pathway of Zong Qi relies on internal grain for substance. Grain entering the Stomach is transmitted to the vessels, overflowing internally and spreading externally. The pure and concentrated parts travel through the meridians and collaterals, circulating endlessly, ending and beginning again, which is called the principle of Heaven and Earth.
If dietary habits are irregular, Stomach qi fails to inspire, and Spleen qi fails to transform and transport. As qi circulates through the hundred vessels, it flows downward, attacking the Liver and Kidney. Earth, Wood, and Water combine, and dampness descends to the feet, causing swelling and pain. Su Jing of the Jin Dynasty termed this "Hong Kong Jiao" (Hong Kong Foot/Gout). To treat this disease, one may eat until full at breakfast, eat less at lunch, and abstain from dinner, which is optimal. One must fear damaging the transporting and transforming qi of the Spleen and Stomach and violating natural rhythms. Moreover, eating at night causes stagnation of blood and qi, following the Yin path, thereby increasing swelling and pain. Ancient people rarely suffered from this disease. Since the southward migration during the Yongjia era, many scholars and officials have suffered from it. After the founding of the Tang Dynasty, military generals garrisoned the far south. The terrain there is low and damp, with accumulated fog and dew. Those unaccustomed to the local environment would all contract this illness. People from Guanxi and north of the Yellow River do not suffer from this disease. The *Waitai Miyao* (Secret Essentials of the Outer Cabinet) also notes that this disease is prevalent in Jiangdong and Lingnan. This is due to clear dampness invading deficiency in the lower body; thus, the classic states, "Pathogenic invasion damages the skin, flesh, sinews, and bones." Therefore, when formulating prescriptions and establishing theories, one must carefully consider the suitability of the local land and climate for treatment.
Observing the current region (the North), it is crisp and dry, lacking low-lying damp areas. Moreover, the cou li (pores/skin texture) are dense, making external pathogens difficult to invade. Yet some still suffer from this disease. Why? It is likely due to excessive consumption of milk, cheese, and strong wine, which belong to the category of water-dampness. Coupled with excessive indulgence, this nourishes the descending nature of damp-water, while Yang qi fails to control it. Consequently, it descends to the feet, accumulating over time to cause swelling, fullness, and pain. This results from the downward flow of diet. How can it be treated by the same methods as those used in the South? One must examine the elevation of the terrain and inquire in detail about diet and living conditions, establishing two therapeutic approaches: one to treat the dampness of the land, and another to treat the downward flow of diet. Medications should be administered according to the appropriate qi, alleviating the patient's suffering, thereby aligning with the principles of Xuanyuan (Yellow Emperor) and Qibo. Sun Simiao stated: "A physician acts with intention (Yi). Adjustments are made according to circumstances; there are no fixed formulas." These are truly insightful words.