The One Cavity of the Mysterious Gate

The valley spirit, undying
Is called the mystical female
The gateway of the mystical female
Is called the root of Heaven and Earth
It flows continuously, barely perceptible
Utilize it, it is never exhausted

Tao Te Ching VI (Laozi or Lao Tzu)

The spirit of the valley – a powerful symbol of the female principle – is eternal. It has always been there and will always be. We can call it the mystical female, or the sacred feminine.
The sacred feminine is the universal source of life. Therefore, the doorway to the essence of the mystical female is what we can call the root, origin, or genesis of the entire world.
This essence – life itself – is a continuous flow. We tend to take it for granted and not pay attention to it, but it is always there. And it does not matter how much it is utilized – the power of life is literally inexhaustible.

Reference:Tao Te Ching: Annotated and Explained by Derek Lin
ISBN 1594732043
p. 12-13

The One Cavity of the Mysterious Gate
also known as the “Mysterious Female”

The Cavity of the mysterious female lies within. Its without structure and form and is limitless. Try to find it, and it will seem as if it is beyond thousands of mountains. Try to locate it, in the heart, liver, spleen, lungs, or kidneys, and you will find nothing. Words cannot describe this cavity. If you try to grasp it, it is nowhere to be found.

The cavity of the Mysterious Gate is the most important gate in the body. The cavity is the mind within the mind. Its not made of flesh and blood, yet its the spirit that directs everything in us. The spirit dwells inside a substantive form. It is there, and yet not there. When the ego is absent, the one cavity of the Mysterious Gate will emerge. However, even if there is only a small trace of ego present, the cavity will disappear.

Reference:Nourishing the Essence of Life: The Inner, Outer, and Secret Teachings of Taoismby Eva Wong
ISBN 1590301048
p.58, 60

The Mysterious Gate has many names. In Confucianism, it is called the altar of wisdom. It embodies limitless compassion. It is a consciousness without thoughts and it reflects the way of heaven. It is intuitive knowledge and reflects the way of earth. In Buddhism, the Mysterious Gate is the spirit mountain, the empty consciousness of original mind, or nirvana, the realm of the Amitabha Buddha. In Taoism, it is the Golden Palace, the realm of t’ai-chi, the domain of the Three Pure Realms, the root of existence of all things. Althought it is given different names by the three religions, it is nonetheless the same thing. In Confucianism, when this gate is opened, the sage emerges. In Buddhism, when this gate is opened, the Buddha
emerges. In Taoism, when this gate is opened, the immortal emerges.

Reference:Cultivating Stillness: Taoist Manual for Transforming Body and Mind by Eva Wong
ISBN 9780877736875
p.18-19

Links:
Tao Te Ching wikipedia.org
Tao Te Ching VI Translated by Derek Lin
The Doctrine of the “Mysterious Female” in Taoism kheper.net
Valley Spirit (Gu Shen, Ku Shen or 谷神) compilation by Michael P. Garofalo egreenway.com

Books:
Holding Yin, Embracing Yang: Three Taoist Classics on Meditation, Breath Regulation, Sexual Yoga, and the Circulation of Internal Energy
by Eva Wong
ISBN 9781590302637