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For males, use the left hand; for females, use the right hand. Take the second phalanx of the middle finger. Bend the finger so that the tips of the two transverse creases at the ends of the second phalanx meet; the distance between these two points is defined as one *cun* (unit of measurement). One may measure using the core of a rice straw or a thin bamboo splint, provided it breaks easily and does not stretch or shrink. If a rope is used, it is inaccurate due to its tendency to stretch or contract.

[Image: Diagram of Middle Finger Standard *Cun* Measurement]

When needling, the degree of depth is determined by the middle finger. The distance between the two crease tips of the bent middle finger's second phalanx serves as one *cun*. For children, regardless of gender, this standard applies directly. For adults, adjustments must be made based on height and body constitution (flexibility vs. principle).

The method relies on the second phalanx of the middle finger: when bent, the distance between the two crease tips is one *cun*. Children follow the same method. Although human bodies vary in height and leanness or robustness, the depth of needle insertion also varies. Individuals with a tall stature have longer finger phalanges, while those with a short stature have shorter phalanges. By measuring the *cun* according to the length of their own finger phalanges, the measurement will naturally be accurate.

Individuals who are obese have thick muscles and abundant Qi and Blood; they are suitable for needle insertion to a depth of three-and-a-half *fen*. Individuals who are emaciated have thin muscles and less developed Qi and Blood; they are suitable for needle insertion to a depth of two *fen*. However, even in such cases, one must understand the principles of fixed rules versus flexible adaptation (*Jing* and *Quan*) and cannot adhere rigidly to a single rule. For individuals of average build, the depth should be酌情 selected between two and three *fen*. As for intuitive understanding and mental grasp, this depends on the practitioner's own insight.

Acupuncture and moxibustion originally suit a sitting posture, following the natural order of the four seasons. Facing the directions of East, South, West, North, and the four intermediate corners, one aligns with the vital Qi, which originates from Heaven.

In each season, there are specific locations where the "Human Spirit" resides; acupuncture and moxibustion are prohibited in these areas to avoid reckless application. In Spring, it is located in the left hypochondrium; in Autumn, in the right side; in Winter, in the waist; and in Summer, at the umbilicus.

The term "Human Spirit" refers to the location where the body's vital energy initially stirs, corresponding to the circulation of Heaven and Earth. Prohibiting acupuncture and moxibustion here is to prevent damaging the vital Qi. Generally, the Human Spirit resides in the Heart, but in Spring it moves to the left hypochondrium because the Liver governs ascending; in Autumn it moves to the right because the Lung governs descending; in Winter it moves to the waist because the Kidney governs storing; and in Summer it moves to the umbilicus because the Spleen governs transformation.

On the 1st day, it is at the big toe of the foot; on the 2nd day, at the lateral malleolus; on the 3rd day, inside the thigh; on the 4th day, in the waist; on the 5th and 6th days, at the mouth; on the 7th day, at the medial malleolus; on the 8th day, at the wrist; on the 9th day, at the sacrum/coccyx; on the 10th day, at the back and waist; on the 11th day, at the nasal bridge; on the 12th day, at the hairline; on the 13th day, at the teeth; on the 14th day, at the Stomach region; on the 15th day, throughout the entire body; on the 16th day, in the chest; on the 17th day, at Qichong (ST30); on the 18th day, inside the thigh; on the 19th day, at the medial malleolus of the foot; on the 20th day, again searching the medial malleolus. On the 21st day, at the little finger of the hand; on the 22nd day, at the lateral malleolus; on the 23rd day, at the Foot-Liver channel area; on the 24th day, at the Hand-Yangming (Large Intestine) channel; on the 25th day, at the Foot-Yangming (Stomach) channel; on the 26th day, in the chest; on the 27th day, at the knee; on the 28th day, at the external genitalia (middle of male and female genitals); on the 29th day, at the tibial shaft; on the 30th day, at the interosseous bones of the ten toes of the foot.