脾位三阴。为六经之内主。以地德而上承乎天。故广明之下。即为太阴太阴掌太仓之出入。为心君储精待用之府。
所以散精微赡运用。为胃行精液者也。其职主运。故以升为德。其部当水谷之海。故以湿为苦。若有余不足。而为病淫
与郁。则水火二气皆能病之。水病则壅。壅则伤气。虚而不运。腹满胀。胃脘痛。肠鸣飧泄。食不化。身体皆重。上为
大寒。火病则不濡。不濡则伤血。血枯而燥。胃气乃浓。善饥肉痿。足不收行。善螈。脚下痛。舌本强。食则呕。食不
下。烦心。水闭黄胆脾约。必也常使少阳和气常动于其中。则土润而升。不伤于燥。土健而运。不伤于湿。斯为得其平
矣。然其居中央孤脏。以灌四旁。而主四末。病则必沦于四脏。而四脏有病。亦必待养于脾。若脾绝、则四脏即无以为
生。是后天之本绝。较捷于先天之根绝也。故治四脏者。不可以不养脾。调停脾胃。医中之王道也。其曰腹满 胀。支
膈胁。下厥上冒。以为过在太阴阳明者。太阴土壅。则本经不运。而阳明之气不腾。是以不能出营卫以升达于上下。
不达于下。则肾气独沉。故下厥。不升于上。则肺气不行。故上冒。此为中气不足。中州之病。是以甚则入脾也。
肾在人身为阴中之少阴。应天时而主冬令。故太阳寒水司气。不归膀胱而归肾。盖以肾之为气。主蛰伏。主归藏。
天地敛藏之气。必归于此。是以寒水唯肾得主之也。顾其脏位为先天根柢。与心火为对待。故又为阴中之太阴。而先天
真火亦涵于此。是虽各以为体。寒为位。而实以火为用也。易象坎。画一阳入二阴之间。为体阳而用阴。其性流行。又
体阴而用阳。人身之肾。其坚滑者水之体。其流动者火之用。得水火两具。而藏命门真火于至阴之中。坎之象也。夫阳
气生于阴中。静极而动。能升阴精以上奉离宅。所谓升坎填离之妙。乃先天之大本大源也。以其火藏水中。水升天上。
故常以水为海。火为龙。水暖而龙潜。水寒而龙起。是以肾家之病。不止水衰为土所克。而又有水火两病也。如湿淫寒
淫所胜。则 肿、骨痛、阴痹、头项痛、时眩、饥不欲食。寒气自伤。则清厥。意不乐。腹大胫肿。喘嗽身重。寝汗出。
龙火为患。则面如漆紫。咳吐则有血。喝喝而喘。心如悬。口热咽干。烦心之类。皆肾家寒湿之淫。与水空火腾之为患
也。至于水藏土中。而所以为蛰藏者。实藉土封之力。经云、肾合精其主脾。是封藏必在脾气。故不曰克而曰生。此前
人补肾。用六味入茯苓山药之妙理也。先哲之言曰。肾家水不足。勿熄其火。须滋阴之源以配火。肾家火不足。勿伤其
水。须益火之主以配水。有旨哉。
The Spleen is located within the Three Yin meridians and serves as the internal master of the Six Meridians. It supports Heaven from Earth, much like the virtue of the earth. Therefore, below "Guangming" (a state of abundant Yang Qi), lies Taiyin (Taiyin Spleen). Taiyin controls the intake and output of the Stomach (the granary) and acts as a storehouse for the Heart Monarch to reserve essence for use.
Thus, its function is to distribute fine nutrients to nourish and facilitate bodily operations, transporting fluid essences for the Stomach. Its primary duty is transportation and transformation, so its virtue is "ascending." Located at the sea of food and fluids, it suffers from dampness. If there is excess or deficiency leading to pathogenic overflow or stagnation, both Water and Fire energies can cause disease.
Water pathology leads to obstruction; obstruction damages Qi, resulting in deficiency and failure to transport, manifesting as abdominal fullness and distension, epigastric pain, borborygmus, undigested stool diarrhea, and heaviness of the body. Severe cases may present with upper-body severe cold. Fire pathology leads to lack of moistening; lack of moistening damages Blood, causing blood dryness and desiccation, while Stomach Qi becomes concentrated (hyperactive/dry-heat), leading to easy hunger but muscle atrophy, weakness of the feet preventing walking, spasms, pain in the soles, stiffness of the tongue base, vomiting after eating, difficulty swallowing, vexation, urinary retention, jaundice, and Pi Yue (Spleen constraint/constipation).
The treatment principle is to constantly maintain the harmonious Qi of Shaoyang moving within, so that Earth remains moist and ascends without injury from dryness, and Earth remains strong and transforming without injury from dampness. This achieves balance.
However, residing in the center, the isolated Zang organ irrigates the four peripheries and governs the four limbs. When diseased, it inevitably affects the other four Zang organs; conversely, when the other four Zang organs are diseased, they must rely on the Spleen for nourishment. If the Spleen fails, the four Zang organs lose their source of life. The destruction of the Postnatal Root is more rapid than the destruction of the Prenatal Root. Therefore, treating diseases of the four Zang organs requires nurturing the Spleen. Harmonizing the Spleen and Stomach is the "King's Way" (gentle and fundamental approach) in medicine.
Regarding symptoms such as abdominal fullness and distension, support across the diaphragm and hypochondrium, lower extremity coldness with upper body dizziness, attributed to disorders of Taiyin and Yangming: Taiyin Earth obstruction causes the meridian itself to fail in transportation, preventing Yangming Qi from ascending. Consequently, Ying and Wei Qi cannot circulate up and down. Failure to descend leads to Kidney Qi sinking alone, causing lower coldness; failure to ascend prevents Lung Qi from circulating, causing upper dizziness. This stems from deficiency of Middle Qi, a disease of the Middle Jiao, which eventually enters the Spleen.
The Kidney is Shao Yin among Yin in the human body, corresponding to the seasonal timing and governing the Winter phase. Thus, the Qi of Solar Cold Water does not return to the Bladder but to the Kidney. This is because the Qi of the Kidney governs hibernation and storage. The converging and storing energy of Heaven and Earth must return here; hence, only the Kidney masters Cold Water.
Considering its position as the root of the Prenatal constitution, opposing Heart Fire, it is also referred to as Tai Yin among Yin, where the Prenatal True Fire is contained. Although they have distinct forms—with Cold being the positional attribute—Fire is actually its functional use. In the I Ching image, Kan (Water trigram) has one Yang line between two Yin lines, representing "Yang in form, Yin in function," with flowing nature; it also represents "Yin in form, Yang in function." In the human body, the firm and slippery aspect of the Kidney is the form of Water, while its mobility is the function of Fire. Possessing both Water and Fire, it stores the True Fire of the Mingmen within extreme Yin, resembling the Kan trigram.
Yang Qi is born within Yin; stillness reaches its limit and generates movement, capable of ascending Yin Essence to offer it to Li (Heart/Fire). This is the subtlety of "Ascending Kan to Fill Li," the great foundation of the Prenatal. Since Fire hides in Water and Water rises to Heaven, Water is often likened to the Sea and Fire to the Dragon. When water is warm, the Dragon hides; when water is cold, the Dragon rises. Therefore, Kidney diseases are not limited to Water deficiency being overcome by Earth, but involve both Water and Fire pathologies.
If Dampness and Cold pathogens prevail, symptoms include edema, bone pain, Yin Bi (pain in the genital/perineal region), headache and neck pain, frequent vertigo, hunger without desire to eat. Self-injury by Cold Qi leads to clear coldness and reversal, unhappiness, abdominal swelling, calf swelling, asthma and cough, body heaviness, and night sweats. If Dragon Fire (Ministerial Fire) causes trouble, symptoms include a face dark as lacquer/purple, hemoptysis, wheezing sounds, a feeling of the heart hanging empty, hot mouth, dry throat, and vexation. These are all harms caused by Cold-Damp excess in the Kidney and the imbalance of Water deficiency with Fire hyperactivity.
Since Water resides within Earth, and the ability to hibernate and store relies on the sealing power of Earth, the Classics state: "The Kidney combines with Essence, governed by the Spleen." This means storage depends on Spleen Qi. Hence, it is said that Earth generates Water rather than overcomes it. This is the profound logic behind previous scholars adding Poria (Fuling) and Dioscorea (Shanyao) to Liuwei Dihuang Wan for tonifying the Kidney.
Ancient sages stated: "When Kidney Water is insufficient, do not extinguish its Fire; instead, nourish the source of Yin to harmonize with Fire. When Kidney Fire is insufficient, do not damage its Water; instead, benefit the Master of Fire to harmonize with Water." There is profound meaning in this.