行针分寸中指传，屈指中节两纹尖，男左女右童稚一，长短肥瘦审经权。
【注】[1]行针取分寸法，以同身寸法为准，男左手，女右手，以中指第二节，
屈指两纹尖，相去为一寸，童稚亦如之。
[2]虽人身有长短，体有肥瘦，入针之分数不一，而身形之长者，
其指节亦长，身形短者，其指节亦短，
但随其长短，以取分寸，则自准矣。
[3]肥人肌肉肥厚，血气充满，宜刺三分半；瘦人肌肉瘦薄，血气末盛，
宜刺二分。
[4]然虽如此，犹当有经有权，不可执一而论，如遇不肥不瘦之人，
祗在二、三分之间，酌量取之可也（图一）。
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出井流荥注为俞，行经入合脏俞原，春宜针荥夏针俞，秋宜针合冬井间，
脏病针俞府病合，脏腑有病皆针原。凡诸井穴肌肉浅，不宜深针自古传。
【注】[1]井、荥、俞、经、合、原，十二经穴名也。
[2]手足阳经有原穴，手足阴经无原穴，阴之俞穴，即阴之原穴也。
[3]所出为井，井者如水之出也；所流为荥，荥者如水之流也；
所注为俞，俞者如水之注也；所行为经，经者如水之行也；
所入为合，合者如水之会也；原者如水之源也。
[4]夫春针荥者，取络脉在分肉间，刺之浅者也；
夏针俞者，取孙络在肌肉皮肤之上也；
秋针合者，亦取络脉在分肉间，故如春时之所刺；
冬针井者，取络脉孙络之下，比他时所刺，则深而留之，
以冬气入脏故也。
[5]经原之原，手足阴阳之经。
[6]诸病皆宜刺入，但所刺有深有浅，不能枚举，此四时针刺之大旨，
自古相传者也。
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The measurement of needle insertion depth is transmitted through the middle finger. By flexing the middle joint, the distance between the tips of the two transverse creases constitutes one Cun (Chinese inch). For males, use the left hand; for females, the right hand; for children, it applies to both. One must examine the meridians and exercise discretion based on height and body constitution (fat or thin).
[Note] [1] The method for measuring needle insertion depth uses the "Same-Body Cun" (Tongshen Cun) standard. For males, use the left hand; for females, the right hand. Bend the second segment of the middle finger; the distance between the tips of the two creases at this segment is defined as one Cun. This method also applies to children.
[2] Although human bodies vary in height and physique (fat or thin), resulting in different needle insertion depths, taller individuals have longer finger segments, while shorter individuals have shorter ones. By adjusting the measurement according to the length of their own finger segments, the accuracy will naturally be achieved.
[3] Individuals with obesity have thick muscles and abundant Qi and Blood, so they are suitable for a needle depth of three-and-a-half Fen (one-tenth of a Cun); individuals with emaciation have thin muscles and immature Qi and Blood, so they are suitable for a needle depth of two Fen.
[4] However, even so, one must understand the principle of flexibility (Jing and Quan) and not adhere rigidly to a single rule. For those who are neither fat nor thin, the depth should be酌情 (discretionarily) selected between two and three Fen (see Figure 1).
Water emerges from Jing-Well points, flows into Ying-Spring points, pours into Shu-Stream points, travels through Jing-River points, and merges into He-Sea points and Yuan-Source points of the Zang and Fu organs. In Spring, Ying-Spring points are indicated; in Summer, Shu-Stream points are indicated; in Autumn, He-Sea points are indicated; in Winter, Jing-Well and Yuan-Source points are indicated. For Zang organ diseases, Shu-Stream points are needled; for Fu organ diseases, He-Sea points are needled; for diseases involving both Zang and Fu organs, Yuan-Source points may be needled. Generally, the muscles over Jing-Well points are shallow, and deep needling is contraindicated, a practice passed down since ancient times.
[Note] [1] Jing-Well, Ying-Spring, Shu-Stream, Jing-River, He-Sea, and Yuan-Source are names of acupoints belonging to the Twelve Meridians.
[2] The Yang meridians of the hands and feet possess Yuan-Source points, whereas the Yin meridians of the hands and feet do not have separate Yuan-Source points; the Shu-Stream point of a Yin meridian serves as its Yuan-Source point.
[3] What emerges is the Jing-Well; "Jing" resembles water emerging from a source. What flows is the Ying-Spring; "Ying" resembles water flowing gently. What pours is the Shu-Stream; "Shu" resembles water pouring in. What travels is the Jing-River; "Jing" resembles water flowing continuously. What merges is the He-Sea; "He" resembles water converging. "Yuan" resembles the source of water.
[4) Needling Ying-Spring points in Spring targets collaterals located between muscle bundles, requiring shallow insertion. Needling Shu-Stream points in Summer targets Luo-Collaterals located above the skin and muscles. Needling He-Sea points in Autumn also targets collaterals between muscle bundles, thus similar to Spring needling. Needling Jing-Well points in Winter targets below the collaterals and Luo-Collaterals; compared to other seasons, the needling is deeper and retention is maintained because the Qi of Winter enters the Zang organs.
[5] The "Yuan" in "Jing and Yuan" refers to the Yuan-Source points of the Hand and Foot Yin and Yang meridians.
[6] All diseases are suitable for needling, but the depth varies and cannot be enumerated here. This summarizes the main principles of seasonal needling, transmitted since ancient times.