难经云。经言能知迎随之气。可令调之。调气之方。必在阴阳。何谓也。然所谓迎
随者。知营卫之流行。经脉之往来。随其逆顺而取之。故曰迎随。调气之方。必在阴阳
者。知其内外表里。随其阴阳而调之。故曰调气之方。必在阴阳。
张世贤注云。手足三阳。手走头而头走足。手足三阴。足走胸而胸走手。此乃经脉
往来定规。凡欲泻者。用针芒向其经脉所来之处。迎其气之方来未盛。乃逆针以夺其
气。是谓之迎。凡欲补者。用针芒向其经脉所去之路。随其气之方去未虚。乃顺针以济
其气。是谓之随。迎随之施。将以调气。调气之术。必在知其病之在阴在阳。随其阴阳
虚实。而施迎随补泻。以调其气焉。内里为阴。外表为阳。内有表里。外亦有表里也。
古人有曰表之表。里之里。正此意也。阳虚阴实。则泻阴而补其阳。阳实阴虚。则泻阳
而补其阴。随其阴阳而调之也。
按男子午前。女子午后。照补泻正法用之。如女子午前。男子午后。则当反其例而
用之。盖男子应日。女子应月。
阴阳升降不同。用针者不可不辨。
例如男子午前。针左手阳经。针芒从外往上为随。针芒从内往下为迎。针左足阳
经。针芒从内往下为随。针芒从外往上为迎。针左足阴经。针芒从外往上为随。针芒从
内往下为迎。针左手阴经。针芒从内往下为随。针芒从外往上为迎。
李南丰注云。手上阳进阴退。足上阳退阴进（一）。合六经起止故也。凡针起穴。
针芒向上气顺行之道。凡针止穴。针芒向下气所止之处。左外右内。令气上行。右外左
内。令气下行。或问午前补泻。与午后相反。男子补泻。与女子相反（二）。盖男子之
气。早在上而晚在下。女子之气。早在下而晚在上。故男子阳经午前呼为补。吸为泻。女
子阳经。午前以吸为补。呼为泻。午后亦反之。或者又曰。补泻必资呼吸。假令尸厥中
风。不能使之呼吸者奈何。曰候其自然之呼吸而转针。若当吸不转。令人以手掩其口
鼻。鼓动其气可也。
噫补泻提插。分男女早晚。其理深微。原为奇经不拘十二经常度。故参互错综如
是。若流注穴。但分左右阴阳可也。
尝爱雪心歌云。
如何补泻有两般。盖是经从两边发。
古人补泻左右分。今人乃为男女别。
男女经脉一般生。昼夜循环无暂歇。
此诀出自梓桑君。我今授汝心已雪。
此子午兼八法而后全也。
《难经》说：经文提到，如果能掌握迎随之气的变化，就可以对气血进行调理。调理气机的方法，关键在于阴阳。这是什么意思呢？回答说：所谓的“迎”和“随”，是指了解营气与卫气（运行于脉中及脉外的两种基本气）的流行规律，以及经脉气血运行的方向。顺着或逆着气血运行的方向来取穴施针，所以称为“迎随”。所谓调理气机的方法，关键在于阴阳，是指清楚病位的内外、表里关系，根据阴阳的属性来进行调理，所以说是调理气机的方法，关键在于阴阳。
张世贤注释说：手三阳经的气血走向是从手走头，再从头走足；手三阴经的气血走向是从足走胸，再从胸走手。这是经脉气血运行方向的固定规则。凡是想要用泻法时，将针尖指向经脉气血来源的方向，迎着气血尚未旺盛之时，逆着气血方向进针以削弱其邪气，这叫做“迎”。凡是想要用补法时，将针尖指向经脉气血离去的方向，随着气血尚未虚弱之时，顺着气血方向进针以资助其正气，这叫做“随”。施行迎随手法，目的是为了调理气机。调理气机的技术，必须在于知道病邪是在阴分还是在阳分，根据阴阳的虚实情况，施行迎随补泻手法，从而调理气机。内部为阴，外部为阳，体内有表里之分，体表也有表里之分。古人曾说“表中之表，里中之里”，正是这个意思。如果是阳气虚而阴气实，就泻阴气而补阳气；如果是阳气实而阴气虚，就泻阳气而补阴气。这都是顺应阴阳特性来进行调理的方法。
按照男子在午前、女子在午后的原则，依照标准的补泻方法使用。如果是女子在午前、男子在午后，则应当反其道而行之。这是因为男子对应太阳（日），女子对应太阴（月）。
阴阳升降的道理不同，使用针灸的人不能不仔细辨别。
例如男子在午前，针刺左手阳经，针尖从外向内、向上为随法；针尖从内向外、向下为迎法。针刺左足阳经，针尖从内向外、向下为随法；针尖从外向内、向上为迎法。针刺左足阴经，针尖从外向内、向上为随法；针尖从内向外、向下为迎法。针刺左手阴经，针尖从内向外、向下为随法；针尖从外向内、向上为迎法。
李南丰注释说：手上部是阳经进气、阴经退气，足部是阳经退气、阴经进气，这是结合六条经脉起止点而言的。凡是从起始穴位下针，针尖向上，是顺应气机运行的方向；凡是到终止穴位下针，针尖向下，是气机停止之处。左侧外侧、右侧内侧下针，可使气上行；右侧外侧、左侧内侧下针，可使气下行。有人问：午前补泻与午后相反，男子补泻与女子相反，这是为什么？回答说：男子的气机，早晨在上部而晚上在下部；女子的气机，早晨在下部而晚上在上部。所以男子阳经在午前呼气时为补，吸气时为泻；女子阳经在午前吸气时为补，呼气时为泻。午后则与此相反。又有人说：补泻必须借助呼吸。假如遇到尸厥（突然昏倒如死状）、中风等患者，无法使其呼吸该怎么办？回答说：等待其自然呼吸节奏来转针。如果该吸气时不转针，可以让别人用手捂住患者的口鼻，鼓动其气息即可。
唉！补泻手法中的提插（向上提为插，向下推为提，此处指捻转提插等手法操作），区分男女早晚，其道理深奥微妙，原本是因为奇经八脉（冲、任、督、带、阴维、阳维、阴跷、阳跷）不拘泥于十二经脉的常规度数，所以参互错综如此复杂。如果是子午流注的特定穴位，只需分左右阴阳即可。
我曾经喜爱《雪心歌》中说：
为什么补泻有两种方式？因为经脉是从身体两侧发出的。
古人补泻按左右区分，今人却按男女区别。
男女的经脉生长是一样的，昼夜循环没有片刻停歇。
这个秘诀出自梓桑君，我今天传授给你，心中冰雪已消融。
这是结合了子午流注和灵龟八法（一种按时开穴的针灸方法）之后才完备的理论。
The *Nan Jing* (Classic of Difficult Issues) states: The classic text mentions that if one can understand the Qi of Ying and Sui (Following and Opposing), one can regulate it. The method for regulating Qi must lie in Yin and Yang. What does this mean? It is answered that what is meant by Ying and Sui is knowing the circulation of Ying Qi (Nutritive Qi) and Wei Qi (Defensive Qi), and the direction of flow in the meridians. By taking points according to whether the flow is against or with the current, it is called Ying and Sui. The statement that the method for regulating Qi must lie in Yin and Yang means knowing the interior and exterior, the deep and superficial aspects, and regulating them according to their Yin or Yang nature. Hence, it is said that the method for regulating Qi must lie in Yin and Yang.
Zhang Shixian commented: The three Yang meridians of the hand and foot run from the hand to the head, and from the head to the foot. The three Yin meridians of the hand and foot run from the foot to the chest, and from the chest to the hand. This is the fixed rule for the direction of meridian flow. Whenever one wishes to apply the reducing method, the needle tip should be directed toward the source from which the meridian Qi comes, opposing the Qi before it becomes abundant, thus inserting the needle against the flow to drain the pathogenic Qi. This is called "Ying" (Opposing). Whenever one wishes to apply the reinforcing method, the needle tip should be directed toward the path where the meridian Qi departs, following the Qi before it becomes deficient, thus inserting the needle with the flow to support the healthy Qi. This is called "Sui" (Following). The application of Ying and Sui aims to regulate Qi. The technique of regulating Qi must depend on knowing whether the disease is in Yin or Yang, and applying Ying-Sui reinforcing and reducing methods according to the deficiency or excess of Yin and Yang to regulate the Qi. The interior is Yin, the exterior is Yang; within the interior there are distinctions of deep and superficial, and similarly on the exterior. The ancients said, "Superficial of the superficial, Interior of the interior," which conveys this meaning. If Yang is deficient and Yin is excessive, one reduces Yin and tonifies Yang. If Yang is excessive and Yin is deficient, one reduces Yang and tonifies Yin. This is regulating according to Yin and Yang.
For men before noon, and for women after noon, apply the standard reinforcing and reducing methods as prescribed. For women before noon, and for men after noon, reverse these principles. This is because men correspond to the Sun (Yang), and women correspond to the Moon (Yin).
The ascending and descending of Yin and Yang differ; those who use acupuncture must distinguish these carefully.
For example, for a man before noon, when needling the Yang meridians of the left hand, directing the needle tip outward and upward constitutes "Sui" (Following); directing it inward and downward constitutes "Ying" (Opposing). When needling the Yang meridians of the left foot, directing the needle tip inward and downward constitutes "Sui"; directing it outward and upward constitutes "Ying". When needling the Yin meridians of the left foot, directing the needle tip outward and upward constitutes "Sui"; directing it inward and downward constitutes "Ying". When needling the Yin meridians of the left hand, directing the needle tip inward and downward constitutes "Sui"; directing it outward and upward constitutes "Ying".
Li Nanfeng commented: On the upper limbs, Yang Qi advances and Yin Qi retreats; on the lower limbs, Yang Qi retreats and Yin Qi advances. This is based on the starting and ending points of the six meridians. When needling a starting point, directing the needle tip upward follows the natural course of Qi flow. When needling an ending point, directing the needle tip downward indicates where Qi stops. Needling the lateral side of the left limb and the medial side of the right limb causes Qi to ascend; needling the lateral side of the right limb and the medial side of the left limb causes Qi to descend. One might ask: Why are reinforcing and reducing methods reversed between morning and afternoon, and why do they differ between men and women? The answer is: Men's Qi is higher in the morning and lower in the evening; women's Qi is lower in the morning and higher in the evening. Therefore, for men's Yang meridians before noon, exhalation is used for reinforcing and inhalation for reducing. For women's Yang meridians before noon, inhalation is used for reinforcing and exhalation for reducing. Afternoon practices are the reverse. Some argue that reinforcing and reducing must rely on respiration. What if one encounters a patient with *Shi Jue* (Corpse-like Fainting) or stroke who cannot breathe voluntarily? The response is: Wait for the patient's natural breathing rhythm to manipulate the needle. If manipulation is needed during inhalation but the patient cannot inhale, another person may cover the patient's mouth and nose with their hand to stimulate airflow.
Alas! The techniques of lifting and thrusting (Lifting and Thrusting) in reinforcing and reducing, differentiated by gender and time of day, involve profound and subtle principles. Originally, this complexity arises because the Eight Extraordinary Vessels (Chong, Ren, Du, Dai, Yin Wei, Yang Wei, Yin Qiao, Yang Qiao) do not strictly follow the regular measures of the Twelve Regular Meridians, leading to such intricate interrelations. However, for acupoints selected via Zi Wu Liu Zhu (Midnight-Noon Ebb-Flow), one only needs to differentiate left and right Yin and Yang.
I have long cherished the *Xue Xin Ge* (Song of Snow-Clear Heart):
Why are there two types of reinforcing and reducing?
Because meridians originate from both sides of the body.
The ancients distinguished reinforcing and reducing by left and right;
Modern practitioners distinguish them by male and female.
Male and female meridians develop identically,
Cycling through day and night without pause.
This secret was passed down by Master Zisang;
Today I impart it to you, clearing your heart like snow.
This completes the theory by combining Zi Wu Liu Zhu with the Ling Gui Ba Fa (Spirit Turtle Eight Methods).