（素问金匮真言论）
故曰∶阴中有阴，阳中有阳。（故曰，引辞也。既言阴矣，而阴中又有阴；既言阳矣，而阳中又有阳。此阴阳之道，
所以无穷，有如下文云者。）平旦至日中，天之阳，阳中之阳也；日中至黄昏，天之阳，阳中之阴也；合夜至鸡鸣，天之
阴，阴中之阴也；鸡鸣至平旦，天之阴；阴中之阳也。（一日之气，自卯时日出地上为昼，天之阳也；自酉时日入地中为
夜，天之阴也。然于阴阳之中，复有阴阳，如午前为阳中之阳，午后则阳中之阴也；子前为阴中之阴，子后为阴中之阳
也。故以一日分为四时，则子午当二至之中，卯酉当二分之令；日出为春，日中为夏，日入为秋，夜半为冬也。）故人亦
应之。（人之阴阳，亦与一日四时之气同。故子后则气升，午后则气降，子后则阳盛，午后则阳衰矣。）夫言人之阴阳，
则外为阳，内为阴。（以表里言。）言人身之阴阳，则背为阳，腹为阴。（以前后言。）言人身之脏腑中阴阳，则脏者为阴，
腑者为阳。肝心脾肺肾五脏皆为阴，胆胃大肠小肠膀胱三焦六腑皆为阳。（五脏属里，藏精气而不泻，故为阴。六腑属表，
传化物而不藏，故为阳。）所以欲知阴中之阴、阳中之阳者何也？为冬病在阴，夏病在阳，春病在阴，秋病在阳，皆视其
所在，为施针石也。（此举一岁之候，以明病治之阴阳也。冬气伏藏故在阴，夏气发越故在阳。春病在阴者，以春阳尚微
而余阴尚盛也。秋病在阳者，以秋阴尚微而余阳尚盛也。必当体察气宜，庶无误治。此虽以四时针石言，而凡药食之类，
无不皆然，不可不为详察也。）故背为阳，阳中之阳，心也；背为阳，阳中之阴，肺也；腹为阴，阴中之阴，肾也；腹为
阴，阴中之阳，肝也；腹为阴，阴中之至阴，脾也。（人身背腹阴阳，议论不一。有言前阳后阴者，如老子所谓万物负阴
而抱阳是也。有言前阴后阳者，如此节所谓背为阳、腹为阴是也。似乎相左。观邵子曰∶天之阳在南，阴在北；地之阴
在南，阳在北。天阳在南，故日处之；地刚在北，故山处之。所以地高西北，天高东南。然则老子所言，言天之象，故
人之耳目口鼻动于前，所以应天阳面南也。本经所言，言地之象，故人之脊膂肩背峙于后，所以应地刚居北也。矧以形
体言之，本为地象，故背为阳，腹为阴，而阳经行于背，阴经行于腹也。天地阴阳之道，当考伏羲六十四卦方圆图，圆
图象天，阳在东南，方图象地，阳在西北，其义最精，燎然可见。又如人之五脏，何以心肺为背之阳，肝脾肾为腹之阴？
盖心肺居于膈上，连近于背，故为背之二阳脏；肝脾肾居于膈下，藏载于腹，故为腹之三阴脏。然阳中又分阴阳，则心
象人之日，故曰牡脏，为阳中之阳。肺象人之天，天象玄而不自明。朱子曰∶天之无星空处谓之辰。故天体虽阳，而实
包藏阴德，较乎日之纯阳者，似为有间。故肺曰牝脏，为阳中之阴。若阴中又分阴阳，则肾属人之水，故曰牝脏，阴中
之阴也。肝属人之木，木火同气，故曰牡脏，阴中之阳也，脾属人之土，其体象地，故曰牝脏，为阴中之至阴也。）此皆
阴阳表里、内外雌雄相输应也，故以应天之阴阳也。（雌雄，即牝牡之谓。输应，转输相应也。此总结上文以人应天之义。
地即天中之物，言天则地在其中矣。牝牡义，见针刺类十七。）
（《素问·金匮真言论》）
所以说：阴中有阴，阳中有阳。（“故曰”是引用之辞。既然已经论述了阴，而阴之中又有阴；既然已经论述了阳，而阳之中又有阳。这就是阴阳的道理无穷无尽的原因，就像下文所说的那样。）
从清晨到中午，是天的阳气，属于阳中之阳；从中午到黄昏，是天的阳气，属于阳中之阴；从夜晚到鸡鸣，是天的阴气，属于阴中之阴；从鸡鸣到清晨，是天的阴气，属于阴中之阳。（一天的气候，自卯时日出地上为白天，属于天的阳气；自酉时日入地中为黑夜，属于天的阴气。然而在阴阳之中，又复有阴阳，如午前为阳中之阳，午后则为阳中之阴；子前为阴中之阴，子后则为阴中之阳。因此将一天分为四个时段，则子时和午时对应冬至和夏至的中点，卯时和酉时对应春分和秋分的时令；日出对应春季，日中对应夏季，日落对应秋季，夜半对应冬季。）
所以人也顺应这种规律。（人的阴阳变化，也与一天四时的气候相同。因此子时之后阳气升发，午后阳气下降，子时之后阳气旺盛，午后阳气衰退。）
说到人的阴阳，则体表为阳，体内为阴。（这是从表里关系来说的。）
说到人体躯干的阴阳，则背部为阳，腹部为阴。（这是从前后的关系来说的。）
说到人体脏腑中的阴阳，则脏者为阴，腑者为阳。肝、心、脾、肺、肾五脏都属于阴，胆、胃、大肠、小肠、膀胱、三焦六腑都属于阳。（五脏属里，贮藏精气而不妄泄，所以为阴。六腑属表，传导水谷化物而不贮藏，所以为阳。）
那么，为什么想知道阴中之阴、阳中之阳是指什么呢？是为了冬天发病在阴分，夏天发病在阳分，春天发病在阴分，秋天发病在阳分，都要观察病位所在，从而施行针刺或砭石治疗。（这里列举一年的四季气候，来说明疾病治疗的阴阳原则。冬天气机伏藏，所以在阴；夏天气机发散，所以在阳。春天发病在阴分，是因为春天的阳气尚微弱而残余的阴气尚旺盛。秋天发病在阳分，是因为秋天的阴气尚微弱而残余的阳气尚旺盛。必须仔细体察气候适宜之处，才不会误治。这虽然是用四季的针石疗法来说明，但凡是药物饮食之类，没有不是这样的，不可不详细考察。）
所以，背部为阳，阳中之阳，对应的是心；背部为阳，阳中之阴，对应的是肺；腹部为阴，阴中之阴，对应的是肾；腹部为阴，阴中之阳，对应的是肝；腹部为阴，阴中之至阴，对应的是脾。（关于人体背腹阴阳的议论不一。有人说前面为阳后面为阴，比如老子所说的“万物负阴而抱阳”。有人说前面为阴后面为阳，就像本节所说的“背为阳、腹为阴”。似乎相互矛盾。看邵雍说：天的阳气在南边，阴气在北边；地的阴气在南边，阳气在北边。天阳在南边，所以太阳处于那里；地刚健在北边，所以山岳处于那里。因此地势西北高，天势东南高。既然如此，老子所言，说的是天的象，所以人的耳目口鼻活动于前方，以应合天阳面南的特性。本经所言，说的是地的象，所以人的脊柱肩背耸立于后方，以应合地刚居北的特性。况且从形体来说，本来也是地的象，所以背为阳，腹为阴，而且阳经行于背部，阴经行于腹部。天地阴阳的道理，应当参考伏羲六十四卦方圆图，圆图象天，阳气在东南，方图象地，阳气在西北，其中的道理最精微，清晰可见。又如人的五脏，为什么心肺位于背部的阳位，肝脾肾位于腹部的阴位？大概心肺居于膈膜之上，连接靠近背部，所以是背部的两个阳脏；肝脾肾居于膈膜之下，储藏承载于腹部，所以是腹部的三个阴脏。然而阳中又分阴阳，则心像人的太阳，所以称为牡脏，是阳中之阳。肺像人的天空，天空景象幽玄而不自我显明。朱熹说：天空中没有星宿的地方叫做辰。所以天体虽然是阳，但实际上包藏着阴德，与纯阳的太阳相比，似乎有所区别。所以肺称为牝脏，是阳中之阴。如果在阴中再分阴阳，则肾属于人的水，所以称为牝脏，是阴中之阴。肝属于人的木，木与火同气，所以称为牡脏，是阴中之阳。脾属于人的土，其形体像大地，所以称为牝脏，是阴中之至阴。）
这些都是阴阳表里、内外雌雄相互输注对应的关系，所以用来应合天的阴阳。（雌雄，就是牝牡的意思。输应，指转输相应。这是对上文以人应天之义的总结。地即天中的事物，说天则地就在其中了。牝牡的含义，见《针刺类》第十七篇。）
(Su Wen, Jin Gui Zhen Lun)
Therefore it is said: Within Yin there is Yin, and within Yang there is Yang. ("Therefore it is said" is a citation marker. Having discussed Yin, yet within Yin there is again Yin; having discussed Yang, yet within Yang there is again Yang. This is why the Dao of Yin and Yang is infinite, as stated in the following text.)
From dawn to noon, this is the Yang Qi of Heaven, belonging to Yang within Yang; from noon to dusk, this is the Yang Qi of Heaven, belonging to Yin within Yang; from nightfall to cockcrow, this is the Yin Qi of Heaven, belonging to Yin within Yin; from cockcrow to dawn, this is the Yin Qi of Heaven, belonging to Yang within Yin. (The Qi of one day: from Mao hour when the sun rises above ground, it is daytime, which is the Yang Qi of Heaven; from You hour when the sun sets below ground, it is nighttime, which is the Yin Qi of Heaven. However, within Yin and Yang, there is again Yin and Yang. For example, before noon is Yang within Yang, while after noon is Yin within Yang; before Zi hour is Yin within Yin, while after Zi hour is Yang within Yin. Thus, dividing one day into four seasons, Zi and Wu correspond to the midpoints of Winter Solstice and Summer Solstice, Mao and You correspond to the times of Spring Equinox and Autumn Equinox; sunrise corresponds to Spring, noon to Summer, sunset to Autumn, and midnight to Winter.)
Therefore, humans also respond to this pattern. (Human Yin and Yang also correspond to the Qi of the four seasons within a day. Thus, after Zi hour, Qi ascends; after Wu hour, Qi descends; after Zi hour, Yang is prosperous; after Wu hour, Yang declines.)
When speaking of human Yin and Yang, the exterior is Yang, and the interior is Yin. (This refers to the relationship between exterior and interior.)
When speaking of the Yin and Yang of the human body trunk, the back is Yang, and the abdomen is Yin. (This refers to the relationship between anterior and posterior.)
When speaking of Yin and Yang within the Zang-Fu organs of the human body, the Zang organs are Yin, and the Fu organs are Yang. The Liver, Heart, Spleen, Lung, and Kidney, these five Zang organs, all belong to Yin; the Gallbladder, Stomach, Large Intestine, Small Intestine, Bladder, and San Jiao (Triple Burner), these six Fu organs, all belong to Yang. (The five Zang organs belong to the interior, storing Essence and Qi without draining, thus they are Yin. The six Fu organs belong to the exterior, transmitting and transforming substances without storing, thus they are Yang.)
So, why inquire about what Yin within Yin and Yang within Yang refer to? It is because diseases in winter occur in the Yin aspect, diseases in summer occur in the Yang aspect, diseases in spring occur in the Yin aspect, and diseases in autumn occur in the Yang aspect. One must observe their respective locations to administer acupuncture or Bian stone therapy. (This cites the seasonal climate of a year to clarify the Yin-Yang principles of disease treatment. Winter Qi hides and stores, hence it is in Yin; Summer Qi expands and disperses, hence it is in Yang. Spring diseases occurring in Yin is because Spring Yang is still weak while residual Yin is still strong. Autumn diseases occurring in Yang is because Autumn Yin is still weak while residual Yang is still strong. One must carefully examine the appropriateness of the Qi to avoid erroneous treatment. Although this discusses needle and stone therapies for the four seasons, this applies equally to medicines and foods, and thus requires detailed examination.)
Therefore, the back is Yang; Yang within Yang is the Heart; the back is Yang; Yin within Yang is the Lung; the abdomen is Yin; Yin within Yin is the Kidney; the abdomen is Yin; Yang within Yin is the Liver; the abdomen is Yin; Yin within Yin is the Extreme Yin, which is the Spleen. (Discussions on the Yin-Yang of the human back and abdomen vary. Some say the front is Yang and the back is Yin, such as Laozi's statement "All things carry Yin and embrace Yang." Others say the front is Yin and the back is Yang, as stated in this section "Back is Yang, Abdomen is Yin." These seem contradictory. Shao Yong said: Heaven's Yang is in the South, Yin in the North; Earth's Yin is in the South, Yang in the North. Heaven's Yang is in the South, so the Sun resides there; Earth's firmness is in the North, so Mountains reside there. Hence, Earth is high in the northwest, and Heaven is high in the southeast. Therefore, what Laozi spoke of referred to the image of Heaven; thus human eyes, ears, mouth, and nose move forward, corresponding to Heaven's Yang facing South. What this classic speaks of refers to the image of Earth; thus human spine and shoulders stand at the rear, corresponding to Earth's firmness residing in the North. Moreover, speaking of physical form, it is originally an image of Earth; thus the back is Yang, the abdomen is Yin, and Yang meridians run along the back, while Yin meridians run along the abdomen. The Dao of Heaven and Earth Yin-Yang should be studied via Fuxi's Square and Round Diagrams of the Sixty-Four Hexagrams. The round diagram images Heaven, with Yang in the Southeast; the square diagram images Earth, with Yang in the Northwest. The meaning is most profound and clearly visible. Furthermore, why are the Heart and Lung located in the Yang position of the back, while the Liver, Spleen, and Kidney are in the Yin position of the abdomen? Generally, the Heart and Lung reside above the diaphragm, connected near the back, thus they are the two Yang Zang organs of the back; the Liver, Spleen, and Kidney reside below the diaphragm, stored and carried in the abdomen, thus they are the three Yin Zang organs of the abdomen. However, within Yang, Yin and Yang are further divided. The Heart resembles the Sun, thus called a Male organ (Mu Zang), being Yang within Yang. The Lung resembles the Sky; the sky's imagery is profound and does not shine brightly itself. Zhu Xi said: The starless parts of the sky are called Chen. Thus, although the celestial body is Yang, it actually contains Yin Virtue, differing somewhat from the pure Yang of the Sun. Thus the Lung is called a Female organ (Pin Zang), being Yin within Yang. If Yin is further divided within Yin, the Kidney belongs to Water in humans, thus called a Female organ (Pin Zang), being Yin within Yin. The Liver belongs to Wood in humans; Wood and Fire share the same Qi, thus called a Male organ (Mu Zang), being Yang within Yin. The Spleen belongs to Earth in humans; its form resembles the Earth, thus called a Female organ (Pin Zang), being the Extreme Yin within Yin.)
These are all the mutual transmission and correspondence of Yin-Yang, exterior-interior, and male-female relationships, thus responding to the Yin-Yang of Heaven. ("Male-female" refers to Pin-Mu. "Transmission and correspondence" means mutual transmission and response. This summarizes the meaning of humans responding to Heaven mentioned above. Earth is a thing within Heaven; speaking of Heaven implies Earth is included within it. The meaning of Pin-Mu is seen in Acupuncture Class, Chapter 17.)