圆图象天，干居东南，坤居西北。
方图象地，干居西北，坤居东南。
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《生气通天论》曰∶阳气者，若天与日，失其所，则折寿而不彰。故天运当以日光明（此明人生全赖乎阳气
也。日不明则天为阴晦，阳不固则人为夭折，皆阳气之失所者，故天不自明，明在日月。月体本黑，得日乃明。
此天运当以日光明也。太阳在午则为昼，而日丽中天，显有象之神明，离之阳在外也。太阳在子则为夜，而火伏
水中，涵无形之元气，坎之阳在内也。天之营运，惟日为本，天无此日，则昼夜不分，四时失序，晦冥幽暗，万
物不彰矣。在于人者，亦惟此阳气为要。苟无阳气，孰厘清浊，孰布三焦，孰为呼吸，孰为营运，血何由生，食何由化，
与天之无日等矣。欲保天年，其可得乎？《内经》一百六十二篇，
惟此节发明天人大义，最为切要，读者详之）。
凡阴阳之要，阳密乃固。两者不和，若春无秋，若冬无夏，因而和之，是谓圣度（阴主内守，阳主外护，
阳密于外，则邪不能侵，而阴得以固于内也。不和者，偏也，偏于阳；若有春而无秋；偏于阴，若有冬而无夏。
和之者，泻其太过，补其不足，俾无偏胜，圣人之法度也）。故阳强不能密，阴气乃绝（阳密则阴固，阳强而
亢，岂能密乎？阴气被扰，将为煎厥而竭绝矣），阴平阳秘，精神乃治（阴血平静于内，阳气秘密于外。阴能
养精，阳能养神，精足神全，命之曰治）。
《五常政大论》曰∶阴精所奉其人寿，阳精所降其人夭（岐伯本论东南阳方，其精降下而多夭，西北阴
方，其精向上而多寿。余尝广之，此阴阳之至理，在人身中者亦然。血为阴，虽肝藏之，实肾经真水之属也。水
者，先天之本也。水旺则阴精充而奉上，故可永年，则补肾宜急也。气属阳，虽肺主之，实脾土饮食所化也，土
者，后天之本也。土衰则阳精败而下陷，故当夭折，则补脾宜亟也。先哲云，水为天一之元，土为万物之母，千
古而下，独薛立斋深明此义，多以六味地黄丸壮水，为奉上之计，兼以补中益气汤扶土，为降下之防，盖洞窥升
降之微，深达造化之旨者欤）。
愚按∶医经充栋，不越于阴阳。诚于体之脏腑腹背、上下表里，脉之左右尺寸。浮沉迟数，时令之春夏
秋冬，岁运之南政北政，察阴阳之微而调其虚实，则万病之本咸归掌握，万卷之富只在寸中，不亦约而不漏，简而可据
乎！
圆图象征天，乾卦位于东南方，坤卦位于西北方。
方图象征地，乾卦位于西北方，坤卦位于东南方。
[图片：方圆图]
[图片：六十四卦图]
《素问·生气通天论》说：“人体的阳气，就像天空和太阳一样，如果失去了它应有的位置和功能，就会折损寿命而不能显扬。”（这段文字阐明了人生全赖阳气。太阳不明亮，天空就会阴暗；阳气不固密，人就会夭折，这都是阳气失其所致的表现。所以天空自身并不发光，光明在于日月。月亮本体是黑色的，得到太阳照射才明亮。这就是说天的运行依靠太阳的光明。当太阳运行到正午时就是白天，太阳高悬中天，显现出有形象的神明，这是离卦的阳在外。当太阳运行到子夜时就是黑夜，火潜伏在水中，蕴含无形的元气，这是坎卦的阳在内。天的运行以日为根本，天如果没有这个太阳，昼夜就无法区分，四季就会失去秩序，昏暗幽暗，万物就不能显扬。在人身上，也只有这阳气是关键。假如没有阳气，谁来清理清浊之气？谁来布散三焦？谁来进行呼吸？谁来进行营运？血液由什么产生？食物由什么消化？这与天没有太阳是一样的。想要保全天然寿命，怎么可能呢？《内经》一百六十二篇中，只有这一节阐发了天人相应的深大义理，最为切要，读者请详细研读。）
大凡阴阳的关键，在于阳气致密然后阴气才能固守。两者如果不协调，就像只有春天而没有秋天，只有冬天而没有夏天。因此要使它们调和，这就叫做圣人的法度。（阴主内守，阳主外护，阳气在外部致密，邪气就不能侵入，而阴气得以在内部固守。所谓不和，就是偏颇，偏于阳，就像有春而无秋；偏于阴，就像有冬而无夏。调和的方法，是泻其太过，补其不足，使没有偏胜，这是圣人的法则。）所以，如果阳气亢盛而不能致密，阴气就会枯竭。（阳气致密则阴气固守，阳气亢盛，怎么能致密呢？阴气被扰动，将会发生煎厥而竭绝。）如果阴气平静，阳气秘固，精神就能正常运作。（阴血在内部平静，阳气在外部秘固。阴能滋养精，阳能滋养神，精足神全，称之为“治”。）
《素问·五常政大论》说：“阴精所奉之处的人长寿，阳精所降之处的人短命。”（岐伯原本论述东南为阳方，其精气降下而人多短命；西北为阴方，其精气向上而人多长寿。我对此加以推广，这阴阳至极的道理，在人身中也同样适用。血属于阴，虽然由肝所藏，实际上属于肾经真水的范畴。水是先天之本。水旺则阴精充盛而上奉，所以可以长寿，因此补肾应当急切。气属于阳，虽然由肺所主，实际上是脾土饮食所化生的，土是后天之本。土衰则阳精败坏而下陷，所以会夭折，因此补脾应当急迫。先哲说，水是天一之元，土是万物之母。千古之下，只有薛立斋深刻明白这个道理，多用六味地黄丸壮水，作为上奉的计划，兼用补中益气汤扶土，作为防止下陷的措施，这大概是透彻洞察了升降的微妙，深深通达造化旨意的人吧。）
我按语道：医学经典堆积如山，但不超出阴阳的范围。确实对于身体的脏腑腹背、上下表里，脉象的左右尺寸、浮沉迟数，时令的春夏秋冬，岁运的南政北政，只要察知阴阳的微妙并调节其虚实，那么万病的根本都在掌握之中，万卷书的丰富知识只存在于寸口脉诊之中，这不也是简约而不遗漏，简单而有依据吗！
The Round Diagram symbolizes Heaven, with the Qian trigram (Heaven) located in the Southeast and the Kun trigram (Earth) in the Northwest.
The Square Diagram symbolizes Earth, with the Qian trigram (Heaven) located in the Northwest and the Kun trigram (Earth) in the Southeast.
[Image: Round and Square Diagrams]
[Image: Sixty-Four Hexagrams Diagram]
The *Suwen* (Basic Questions), chapter "Shengqi Tongtian Lun" (Treatise on the Connection between Vital Qi and Heaven), states: "Human Yang Qi is like Heaven and the Sun; if it loses its proper place/function, lifespan will be shortened and vitality will not be manifest." (This passage clarifies that human life relies entirely on Yang Qi. If the sun is not bright, the sky becomes dark and gloomy; if Yang Qi is not secure, humans suffer premature death; these are all manifestations of Yang Qi losing its proper state. Thus, Heaven does not shine by itself; its brightness comes from the Sun and Moon. The moon's body is originally black and becomes bright only when illuminated by the sun. This illustrates that Heaven's operation depends on the Sun's brightness. When the sun reaches noon, it is day; the sun hangs high in the middle of the sky, revealing visible divine illumination, representing the Yang of the Li trigram being outside. When the sun reaches midnight, it is night; fire lies hidden in water, containing invisible primordial Qi, representing the Yang of the Kan trigram being inside. Heaven's operation takes the Sun as its root. Without this Sun, Heaven would have no distinction between day and night, the four seasons would lose their order, darkness would prevail, and all things would fail to manifest. In humans, only this Yang Qi is essential. Without Yang Qi, who would clarify the clear and turbid? Who would distribute Sanjiao (Triple Burner)? Who would facilitate respiration? Who would conduct circulation? How would blood be generated? How would food be digested? This is equivalent to Heaven without a Sun. Is it possible to preserve one's natural lifespan under such conditions? Among the 162 chapters of the *Neijing*, only this section elucidates the profound principles of the correspondence between Heaven and Humanity, making it most crucial for readers to study carefully.)
Generally, the key to Yin and Yang is that Yang must be dense/secure so that Yin can be solidified. If the two are not in harmony, it is like having Spring without Autumn, or Winter without Summer. Therefore, harmonizing them is called the standard of the Sages. (Yin governs internal retention, while Yang governs external protection. If Yang is dense externally, pathogenic factors cannot invade, allowing Yin to remain solid internally. Disharmony refers to bias: bias toward Yang is like having Spring without Autumn; bias toward Yin is like having Winter without Summer. Harmonization involves draining excess and tonifying deficiency, ensuring neither dominates, which is the method of the Sages.) Thus, if Yang is excessive and cannot maintain density, Yin Qi will perish. (If Yang is dense, Yin is solid; if Yang is hyperactive, how can it be dense? Yin Qi, disturbed, will suffer from Jian Jue [Frying Syncope] and exhaust itself.) However, if Yin is peaceful and Yang is securely retained, Jing and Shen (Spirit) will function properly. (Yin Blood is calm internally, Yang Qi is secure externally. Yin nourishes Jing, Yang nourishes Shen. With abundant Jing and complete Shen, this state is termed "Zhi" [Governance/Health].)
The *Suwen*, chapter "Wuchang Zheng Da Lun" (Great Treatise on the Normal Policies of the Five Constants), states: "Those where Yin Essence is offered up live long; those where Yang Essence descends die young." (Qibo originally discussed the Southeast as a Yang region, where essence descends and people often die young; the Northwest as a Yin region, where essence rises and people often live long. I have expanded upon this: this ultimate principle of Yin and Yang applies equally within the human body. Blood belongs to Yin; although stored by the Liver, it actually falls under the category of True Water of the Kidney Meridian. Water is the Root of Pre-Heaven. When Water is prosperous, Yin Essence is abundant and offered upward, thus enabling longevity; therefore, tonifying the Kidney should be urgent. Qi belongs to Yang; although governed by the Lungs, it is actually transformed from food and drink by Spleen Earth. Earth is the Root of Post-Heaven. When Earth declines, Yang Essence deteriorates and sinks downward, leading to premature death; therefore, tonifying the Spleen should be urgent. Ancient sages said, Water is the Origin of Tian Yi (Number One), and Earth is the Mother of All Things. Since ancient times, only Xue Lizhai deeply understood this meaning, frequently using Liuwei Dihuang Wan (Six-Ingredient Rehmannia Pill) to strengthen Water as a plan for offering upward, and simultaneously using Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction) to support Earth as a prevention against sinking. This person likely penetrated the subtleties of ascending and descending and deeply comprehended the purport of creation.)
My commentary: Medical classics fill shelves, yet they do not exceed the scope of Yin and Yang. Indeed, regarding the Zang-Fu organs, abdomen and back, upper and lower, interior and exterior of the body; the pulse positions of left and right, cun and chi; the qualities of floating, sinking, slow, and rapid; the seasons of Spring, Summer, Autumn, and Winter; and the annual movements of South Governance and North Governance, if one observes the subtleties of Yin and Yang and regulates their deficiency and excess, then the roots of ten thousand diseases fall under control, and the richness of ten thousand volumes resides within the inch-pulse. Is this not concise yet comprehensive, simple yet reliable?