六十九难曰虚者补其母。实者泻其子。当先补之。然后泻之(此以别经为子母也。母。
生我
之经。如肝虚则补肾。经也母气实。则生之益力。子。我生之经如。肝实则泻心经也。子气
衰。则食其母益甚)不虚不实。以经取之者。是正经自生病。不中他邪也。当自取其经。故
言以经取之(即于本经取所当刺之穴。不必补母泻子也)
七十五难曰。东方实。西方虚。泻南方。补北方。何谓也。然金木水火土。当更相平(
言金
克木。木克土。循环相制。不令一藏独盛而生病也)东方木也。西方金也。木欲实。金当平
之。火欲实。水当平之。土欲实。木当平之。金欲实。火当平之。水欲实。土当平之。东方
者肝也。则知肝实。西方者肺也。则知肺虚。泻南方火。补北方水。火者木之子也。木者木
之母也。水胜火。(泻火者。一则以夺木之气。一则以去金之克。补水者。一则以益金之气
。一则以制火之光。故曰水胜火)子能令母实。母能令子虚。故泻火补水。欲令金得平木也(
母能令子实。子能令母虚。乃五行之生化。即虚者补母。实者泻子之义。今言子能令母实。
母能令子虚者。用针之子夺也)经曰。不能治其虚。何问其余。此之谓也(虚指肺虚而言也)
七十二难曰。所谓迎随者。知营卫之流行。经脉之往来。也随其逆顺而取之故曰迎随(迎者
针锋逆其来处为泻。随者针锋顺其往处为补。)
《难经》第六十九难说：虚证要补其母穴，实证要泻其子穴。应当先进行补法，然后再进行泻法。（这是指通过不同经脉之间的母子关系来施治。母，即生我之经，如肝虚则补肾经，因为母气实，则生助之力更强；子，即我生之经，如肝实则泻心经，因为子气衰，则会进一步消耗母气。）不虚不实的病证，则直接取本经穴位治疗。这是因为正经自身发病，没有受到其他邪气的干扰，所以应当直接选取本经的穴位，因此说“以经取之”（即在原发病的本经上选取应当针刺的穴位，不需要采用补母或泻子的方法）。
《难经》第七十五难说：东方实，西方虚，泻南方，补北方。这是什么意思呢？回答是：金、木、水、火、土五行应当相互平衡。（意思是金克木，木克土，循环相制，不让某一脏独盛而生病。）东方属木，西方属金。木欲实，金当平之；火欲实，水当平之；土欲实，木当平之；金欲实，火当平之；水欲实，土当平之。东方对应肝脏，所以知道是肝实；西方对应肺脏，所以知道是肺虚。泻南方的火，补北方的水。火是木之子，水是木之母。水能胜火。（泻火的目的，一方面是为了剥夺木之气，另一方面是为了去除金的克制；补水的目的，一方面是为了益金之气，另一方面是为了制约火的过亢，所以说水胜火。）子能令母实，母能令子虚。所以泻火补水，是想让金得以平衡木。（母能令子实，子能令母虚，这是五行生化规律，也就是“虚者补母，实者泻子”的含义。现在说“子能令母实，母能令子虚”，是指运用针刺手法中的“子夺”原理。）经文说：“不能治其虚，何问其余。”说的就是这个道理（这里的“虚”特指肺虚而言）。
《难经》第七十二难说：所谓迎随，是指了解营卫之气的流行和经脉气血的往来，顺着或逆着气血运行的方向进行针刺，所以称为迎随。（迎，指针锋逆着气血来的方向刺为泻法；随，指针锋顺着气血去的方向刺为补法。）
Chapter 69 of the *Nan Jing* (Classic of Difficult Issues) states: For deficiency syndromes, tonify its mother; for excess syndromes, sedate its child. One should first apply tonification, then apply sedation. (This refers to using the mother-child relationship between different meridians. The "mother" is the meridian that generates me; for example, if the Liver is deficient, one tonifies the Kidney meridian, as a strong mother qi generates more power. The "child" is the meridian generated by me; for example, if the Liver is in excess, one sedates the Heart meridian, as a weak child qi further depletes the mother.) For conditions that are neither deficient nor excessive, treat by selecting points from the affected meridian itself. This is because the primary meridians are diseased due to their own pathology, without interference from external pathogens, so one should directly select points from that meridian. Hence it is said to "treat according to the meridian" (i.e., select appropriate acupuncture points on the original meridian without needing to tonify the mother or sedate the child).
Chapter 75 of the *Nan Jing* states: When the East is in excess and the West is deficient, sedate the South and tonify the North. What does this mean? The answer is: Metal, Wood, Water, Fire, and Earth must maintain mutual balance. (This means Metal controls Wood, Wood controls Earth, creating a cycle of restraint so that no single Zang organ becomes excessively dominant and causes disease.) The East corresponds to Wood, and the West to Metal. If Wood tends toward excess, Metal should regulate it; if Fire tends toward excess, Water should regulate it; if Earth tends toward excess, Wood should regulate it; if Metal tends toward excess, Fire should regulate it; if Water tends toward excess, Earth should regulate it. The East corresponds to the Liver, indicating Liver excess; the West corresponds to the Lungs, indicating Lung deficiency. Sedate the Fire of the South and tonify the Water of the North. Fire is the child of Wood, and Water is the mother of Wood. Water overcomes Fire. (Sedating Fire serves two purposes: to drain the Qi of Wood and to remove the restraining influence of Metal. Tonifying Water also serves two purposes: to benefit the Qi of Metal and to restrain the excessive brilliance of Fire. Thus, it is said that Water overcomes Fire.) The child can cause the mother to be full, and the mother can cause the child to be empty. Therefore, sedating Fire and tonifying Water aims to allow Metal to balance Wood. (The mother causing the child to be full, and the child causing the mother to be empty, represents the generative and transformative laws of the Five Elements, which aligns with the principle of "tonify the mother for deficiency, sedate the child for excess." The statement here that "the child causes the mother to be full, and the mother causes the child to be empty" refers to the application of the "sedation via the child" technique in acupuncture.) The Classic states: "If you cannot treat the deficiency, why ask about the rest?" This refers to this very principle (here, "deficiency" specifically refers to Lung deficiency).
Chapter 72 of the *Nan Jing* states: The term "Ying-Sui" (Following and Opposing) refers to understanding the circulation of Ying and Wei Qi and the flow of Qi and Blood in the meridians. Acupuncture is applied following or opposing these directions, hence the name Ying-Sui. ("Ying" [Opposing], where the needle tip opposes the direction of incoming Qi, constitutes sedation; "Sui" [Following], where the needle tip follows the direction of outgoing Qi, constitutes tonification.)