Tenouchi (the world inside the hands) as utilized in both swordsmanship and the science of hand mudras (inkei) involves the distinct roles of the left and right hands, the individual fingers, the parts of the palm, and their innate correspondences. The hands play a hugely significant role in energetic flow, mental stability, intuitive response, and the refinement of action. This is both highlighted by and cultivated through the sword arts. Tenouchi is the ura or secret world of this practice, and it is thought to require thirty years of practice to fully unfold its potential. The following information will be helpful during that journey, if used wisely and sparingly.
Three Yin meridians—Lung, Heart Protector, and Heart—flow inward over the inner hand; three Yang meridians—Large Intestine, Triple Heater, and Small Intestine—flow outward across the back of the hand. All six channels are present in both hands, but for the sake of clarity and to reflect the subtle difference in emphasis between the hands, these are split between left and right in the diagram (figure 20).
The most important tsubos or energy points coincide with important parts of the tenouchi. The points H9, “Inwards Rushing Yin” and SI 3, “Back Stream” (that is, Yang curving back) are located where the sword is held most strongly. This is the source of power in the hands and links the sword with the inner body. SI 3 has a special connection with the central channel and the spine, and stimulation of this point relaxes the sinews throughout the body.
The power of the sword’s movements is contained by the Dragon’s Mouth (also known as the Tiger’s Mouth). This structure is formed by the Large Intestine and Lung meridians and especially the thick muscled area of LI 4 (Adjoining Valley), which moves directly over the mine1 at the completion of a cut. The full significance of these points can only be realized through an understanding of the entire energetic structure. Thus the Dragon’s Mouth is controlled by the Yang lines from the back and shoulder blades, through the outer arms. The many points in the wrist are also of great importance and are linked to the generation of power in the swing, the flexibility of all the joints, and mental equilibrium.
The use of inkei in Mikkyo, especially in Shingon, utilizes the inherent connections between the different areas of the hands and other parts of the body as well as the corresponding forces within the external universe to manipulate energy and consciousness. There is also an inherent connection between the two hands and the two sides of the body, which in turn reflects different energetic functions. The left hand is the moon hand and relates to cooling, pacifying, and nurturing functions. The right hand is the sun hand and relates to heating, dynamic, and performing functions. The left hand symbolizes the world of natural phenomena (matrix mandala), and the right hand the world of the observing consciousness (diamond or vajra mandala). Much of the information contained in these mandalas is transposed onto the hands, giving a further dimension to the practice of inkei and the rituals they are used in.
The left hand is the elimination of obstacles and is called principle (ri); this is the Matrix World (Taizokai). The right hand discerns various things and is called wisdom (chi); this is the Diamond World (Kongokai). The five fingers of the left hand represent the Five Wisdoms of the Taizokai; the five fingers of the right hand represent the Five Wisdoms of the Kongokai. The left hand is Concentration. The right hand is Wisdom. The ten fingers are the ten stages. They are called the ten worlds of Essence (hokkai) or the ten thusnesses (shinnyo). By reduction [all] this comes to the One: by extension, there are many names. The left little finger is Charity; the ring finger, Discipline; the middle finger, Patience; the index [finger], Energy; the thumb, Contemplation. The right little finger is Wisdom; the ring finger, Means; the middle finger, Vow; the index [finger], Power; the thumb, Wisdom. The little finger [of both hands] is Earth; the ring finger, Water; the middle finger, Fire; the index [finger], Air; the thumb, Void.
—FROM THE FUDARAKUKAIEKI BUKKYO DAIJITEN2
1. The spine of the sword; see appendix IV, Sword Nomenclature.
2. Translated by E. Dale Saunders in Mudra: A Study of Symbolic Gestures in Japanese Buddhist Sculpture. New York: Princeton University Press, 1972.