In acupuncture, there are 12 regular meridians; these, along with the 2 extraordinary channels known as the governing and conception vessels, are the ones most commonly depicted on acupuncture charts and models. There are, however, 73 channels in total, and include the cutaneous, musculo-skeletal, divergent, extraordinary, transverse luo, longitudinal luo, and internal channels. I will write more on this in the future. This article is about the internal branch of the Heart channel.
The internal branch of the Heart channel arises from the center of the heart and emerges at the center of the pupil. (I am capitalizing the term Heart to refer to the Chinese organ, and keeping it in small letters to refer to the physical organ. See also Why are some Chinese Terms Capitalized.) There is little discussion of this channel in modern texts. A key to its function lies in its connection with the Small Intestine channel.
The Small Intestine channel is the Yang, hollow bowel that is paired in the Fire element with the Heart. The Small Intestine has the function of “separating the pure from the impure.” Digestively and otherwise, it sorts out what is essential and passes the rest for elimination to the Large Intestine.
The Chinese character for Heart – 心 / Xin – also means “mind.” Chinese medicine asserts that the Heart houses the mind. But it is not the ordinary mind; it is the unconditioned, clear Mind.
As the ruler/emperor/empress of the body, the Heart has the function of creating harmony. It enables us to perceive clearly, without obscuration. This capacity is aided by the Small Intestine, which separates the pure and conveys this to the Heart. We normally see through our “regular eyes”, which can be clouded with conditioning and experience. This type of seeing is through the action of the regular mind and cognition. The inner channel of the Heart allows us to perceive with clarity and direct experience.
In relation to health, the emotion of the Heart is joy. In part, this arises when we are able to interact with others and with our surroundings as they are. To the extent that we can accurately perceive, communicate, listen, and see, we are able to experience joy. In Chinese medicine, this capacity is cultivated through meditation, qigong, dreamwork, and self-reflection. We often are concerned with health as it relates to our physical body. We think about exercise, diet, blood tests, etc., but sometimes neglect our inner health. As it is now the time of summer/Fire/Heart, take this time to tend to your Heart/Mind.
How can a person know the Dao? By the heart.
How can the heart know? By emptiness, the pure attention that unifies being and quietude.
The heart is never without treasure, yet it is called empty.
The heart is never completely filled, yet it is called unified.
The heart is never without movement, yet it is called quiet.
The heart is alive, and possesses knowledge; it knows, and from knowing makes distinctions.
To make distinctions is to know all parts of the whole at once.
Xunzi, Confuscian philosopher from 3rd century B.C. Translated by Burton Watson
(This quote is from my article Propriety – The Virtue of the Heart)