，若有若无，此言实之与虚，若得若失。盖得失有无，义实相同，互举之省文耳。
八十一难曰∶经言有见如入，有见如出者，何谓也？然所谓有见如入者，谓左手见气来
至乃内针，针入见气尽乃出针。是谓有见如入，有见如出也。
滑氏曰∶所谓有见如入下，当欠有见如出四字，如读为而，孟子书，望道而未之见。而
读为
如，盖通用也。有见而入出者，谓左手按穴，待气来至乃下针，针入候其气应尽而出针也。
纪氏曰∶针之出入，皆随气往来。《素问》曰∶见其乌乌，见其稷稷，从见其飞，不知其谁
，伏如横努，起如发机是也。（《素问》宝命全角论文）
八十一难曰∶经言无实实虚虚，损不足而益有余。是寸口脉耶，将病自有虚实耶，其损
益奈
何？然是病，非谓寸口脉也，谓病自有虚实也。假令肝实而肺虚，肝者木也，肺者金也，金
木当更相平，当知金平木，假令肺实而肝虚微少气，用针不补其肝而反重实其肺。故曰实实
虚虚，损不足而益有余，此者中工之所害也。
滑氏曰∶是病二字，非误即衍。肝实肺虚，金当平木如七十五难之说。若肺实肝虚，则
当抑
金而扶木也。用针者乃不补其肝，而反重实其肺，此所谓实其实而虚其虚。损不足而益有余
，杀人必矣。中工，犹云粗工也。
十二难曰∶五脏脉已绝于内，用针者反实其外。五脏脉已绝于外，用针者反实其内。内
外之
绝，何以别之？然五脏脉已绝于内者，肾肝气已绝于内也，而医反补其心肺。五脏脉已绝于
外者，其心肺脉已绝于外也，而医反补其肾肝。阳绝补阴，阴绝补阳，是谓实实虚虚，损不
足，益有余。如此死者，医杀之耳。
滑氏曰∶《灵枢》第一篇曰∶凡将用针者，必先诊脉，视气之剧易，乃可以治也。又第
三篇
曰∶所谓五脏之气已绝于内者，脉口气内绝不至，反取外之病处，与阳经之合，有留针以致
其阳气，阳气至则内重竭，重竭则死矣。其死也，无气以动故静。所谓五脏之气已绝于外者
，脉口气外绝不至，反取其四末之输，有留针以致其阴气，阴气至则阳气反入，入则逆，逆
则死矣。其死也，阴气有余故躁。此《灵枢》以脉口内外言阴阳也，越人以心肺肾肝内外别
阴阳，其理亦犹是也。纪氏谓此篇言针法，冯氏谓合入用针补泻之类。
如果感觉针下有气似有若无，这是指补法与泻法的效果，如同得到或失去正气一样。所谓得失有无，含义实际上是相同的，只是互相列举时的省略写法罢了。
《难经》第八十一难说：经文提到“有见如入，有见如出”，这是什么意思呢？回答说：所谓的“有见如入”，是指左手按压穴位，感觉到经气到来时才进针；针进入后，等到经气散尽才出针。这就叫做“有见如入”和“有见如出”。
滑寿（滑氏）说：在“有见如入”之下，应当补上“有见如出”这四个字。如果把“而”读作“如”，就像《孟子》书中说的“望道而未之见”，这里的“而”通假为“如”，是通用的用法。“有见而入出”，是指左手按压穴位，等待经气到来才下针，针入后观察经气应该耗尽时再出针。
纪昀（纪氏）说：针刺的进出，都随着经气的往来而变化。《黄帝内经·素问》中说：“看见它乌乌聚集，看见它稷稷众多，跟随它飞翔的样子，不知道是谁在驱使，潜伏时像横弩待发，发作时像发射箭机一样迅速。”（出自《素问·宝命全形论》）
《难经》第八十一难又说：经文说不要“实实虚虚”，即不要损伤不足的正气而增加有余的邪气。这是指寸口脉而言，还是指疾病本身自有虚实呢？这种损益应该如何操作呢？回答说：这里所说的病，不是指寸口脉，而是指疾病本身自有虚实。假如肝实而肺虚，肝属木，肺属金，金和木应当相互制约平衡，应当知道用金来平抑木。假如肺实而肝虚，导致气微少，使用针刺时如果不补益肝脏，反而加重肺实的状况。所以说“实实虚虚”，损伤不足的正气而增加有余的邪气，这是中等水平的医生造成的危害。
滑寿（滑氏）说：“是病”这两个字，如果不是错误就是衍文。肝实肺虚，金应当平抑木，如同第七十五难所说的道理。如果是肺实肝虚，就应当抑制金而扶助木。使用针刺的人却不补益肝脏，反而加重肺实，这叫做“实其实而虚其虚”。损伤不足的正气而增加有余的邪气，必然导致死亡。中工，也就是粗工的意思。
《难经》第十二难说：五脏的内脏之气已经在内部衰竭，使用针刺的人反而充实外部。五脏的外脏之气已经在外部衰竭，使用针刺的人反而充实内部。内部的衰竭和外部的衰竭，如何区别呢？回答说：五脏之气已经在内部衰竭，是指肾气和肝气已经在内部衰竭，但医生反而补益心肺。五脏之气已经在外部衰竭，是指心气和肺气已经在外部衰竭，但医生反而补益肾肝。阳气衰竭却补阴，阴气衰竭却补阳，这就是所谓的“实实虚虚”，损伤不足，增加有余。这样导致死亡的，是医生杀死了病人。
滑寿（滑氏）说：《灵枢》第一篇说：凡是准备使用针刺的人，必须先诊察脉象，观察病气的轻重难易，然后才可以进行治疗。又第三篇说：所谓五脏之气已经在内部衰竭，是指脉口的内里脉搏跳动不能到达（指沉取无脉），医生反而去取外部的病处以及阳经的合穴，留针以引致阳气，阳气到来则内部更加枯竭，双重枯竭就会死亡。他死的时候，因为没有气推动所以表现为安静。所谓五脏之气已经在外部衰竭，是指脉口的外表脉搏跳动不能到达（指浮取无脉），医生反而取其四肢末端的输穴，留针以引致阴气，阴气到来则阳气反而内陷，内陷则逆乱，逆乱就会死亡。他死的时候，因为阴气有余所以表现为躁动。这是《灵枢》以脉口的内外来区分阴阳。越人（秦越人/扁鹊）用心肺和肾肝的内外来分别阴阳，其中的道理也是一样的。纪氏认为这篇讲的是针法，冯氏认为应当归入使用针刺补泻之类的内容。
If the sensation of Qi under the needle seems to exist and not exist, this refers to the effects of tonification and sedation, akin to gaining or losing Zheng Qi (True Qi). The concepts of gain/loss and existence/non-existence are essentially identical in meaning; they are merely elliptical expressions used for mutual illustration.
Chapter 81 of the *Nan Jing* (Classic of Difficult Issues) states: "The classics mention 'entering as if seeing' and 'exiting as if seeing'. What does this mean?" The answer is: By "entering as if seeing," it means that when the left hand presses the acupoint and the arrival of Qi is perceived, the needle is inserted. Once the needle is inserted, one waits until the Qi has dissipated before withdrawing the needle. This is called "entering as if seeing" and "exiting as if seeing."
Hua Shou (Master Hua) states: Below the phrase "entering as if seeing," the four characters "exiting as if seeing" should be added. If one reads "er" (而) as "ru" (如), as seen in the *Mencius* text "gazing at the Dao but not yet seeing it," where "er" is interchangeable with "ru," this indicates common usage. "Entering and exiting upon perceiving [Qi]" means pressing the acupoint with the left hand, waiting for the arrival of Qi before inserting the needle, and observing within the needle until the Qi should have exhausted itself before withdrawing it.
Ji Yun (Master Ji) states: The insertion and withdrawal of the needle all follow the coming and going of Qi. As stated in the *Su Wen* (Basic Questions): "You see it gathering like a flock of birds, you see it abundant like millet stalks, following its flight, unaware of who drives it; it lies hidden like a crossbow ready to fire, and rises suddenly like the release of an arrow mechanism." (From the *Su Wen*, Chapter on Complete Preservation of Life Form).
Chapter 81 of the *Nan Jing* further states: "The classics say: Do not tonify excess and sedate deficiency, do not damage what is insufficient and benefit what is already excessive." Does this refer to the Cun Kou pulse, or does it refer to the disease itself possessing excess and deficiency? How should these tonifications and sedations be applied? The answer is: Here, "disease" does not refer to the Cun Kou pulse, but rather to the inherent excess and deficiency of the disease itself. For example, if the Liver is Excess and the Lung is Deficient: The Liver belongs to Wood, and the Lung belongs to Metal. Metal and Wood should mutually balance each other; one must understand using Metal to level Wood. Conversely, if the Lung is Excess and the Liver is Deficient, resulting in scanty Qi, and the practitioner uses acupuncture without tonifying the Liver but instead reinforces the Lung's Excess, this is termed "tonifying excess and sedating deficiency," damaging the insufficient and benefiting the excessive. This is the harm caused by average physicians (Zhong Gong).
Hua Shou (Master Hua) states: The two characters "shi bing" (this disease) are either an error or a superfluous addition. In cases of Liver Excess and Lung Deficiency, Metal should level Wood, as explained in Chapter 75. If the Lung is Excess and the Liver is Deficient, one should suppress Metal and support Wood. If the practitioner fails to tonify the Liver and instead reinforces the Lung's Excess, this is called "making the excess truly excess and the deficiency truly deficient." Damaging the insufficient and benefiting the excessive will certainly lead to death. "Zhong Gong" (average physician) is synonymous with "Cu Gong" (crude physician).
Chapter 12 of the *Nan Jing* states: When the internal Qi of the Zang organs has exhausted internally, the practitioner wrongly tonifies the exterior. When the external Qi of the Zang organs has exhausted externally, the practitioner wrongly tonifies the interior. How can one distinguish between internal and external exhaustion? The answer is: When the Qi of the Zang organs has exhausted internally, it means the Qi of the Kidney and Liver has exhausted internally, yet the physician wrongly tonifies the Heart and Lung. When the Qi of the Zang organs has exhausted externally, it means the Qi of the Heart and Lung has exhausted externally, yet the physician wrongly tonifies the Kidney and Liver. Tonifying Yin when Yang is exhausted, and tonifying Yang when Yin is exhausted, constitutes "tonifying excess and sedating deficiency," damaging the insufficient, and benefiting the excessive. Those who die in such manner are killed by the physician.
Hua Shou (Master Hua) states: The first chapter of the *Ling Shu* (Spiritual Pivot) says: "Whenever one intends to use needles, one must first diagnose the pulse, observe the severity and ease of the Qi, and only then can treatment proceed." The third chapter also states: "What is meant by the Qi of the Five Zang organs exhausting internally is that the pulse at the Cun Kou does not reach internally [on deep pressure]. If one wrongly selects diseased areas externally and the He-Sea points of the Yang meridians, retaining the needle to draw out Yang Qi, the arrival of Yang Qi will cause double depletion internally, leading to death due to total exhaustion. Upon death, there is no Qi to move, hence the body is still. What is meant by the Qi of the Five Zang organs exhausting externally is that the pulse at the Cun Kou does not reach externally [on superficial pressure]. If one wrongly selects the Shu points of the four extremities, retaining the needle to draw out Yin Qi, the arrival of Yin Qi will cause Yang Qi to retreat inward. Retreating inward leads to reversal, and reversal leads to death. Upon death, there is excess Yin Qi, hence the body is restless." This is how the *Ling Shu* distinguishes Yin and Yang based on the internal and external aspects of the Cun Kou pulse. Yue Ren (Bian Que) distinguishes Yin and Yang based on the internal and external aspects of the Heart/Lung and Kidney/Liver; the principle remains the same. Master Ji considers this chapter to discuss needle techniques, while Master Feng believes it should be classified under the application of acupuncture tonification and sedation methods.