Taoism is a source of some of the world's oldest Mind-Body health and healing lore. Taoists often call their study the "science of essence and life" to represent their cultivation of those Arts. The science of essence deals with the mind; the science of life deals with the body. Their object is to groom and enhance what Taoists call the three bases or three treasures of human existence: vitality, energy and spirit.
Vitality, energy and spirit are envisioned as three centers of the individual and collective organism. Each center is twofold: there is a primal or abstract noumenon, and a temporal or concrete phenomenon. There are many differences in Taoist practices according to which aspect of what center they are primarily designed to affect.
Vitality is primally associated with creativity, temporally associated with sexuality. Energy is primally associated with movement, heat and power, temporally associated with breath, magnetism and strength. Spirit is primally associated with the essence of mind and consciousness, temporally associated with thought and reflection. As the three centers interact, the quality and proportion of their mutual influence relate directly to the total state of mental and physical well-being.
In terms of the individual body, vitality is associated with the loins, energy with the thorax, and spirit with the brain. These associations are invoked in some forms of Taoist health practice, where the respective areas of the body are called the lower, middle and upper fields of elixir(Dantien). These fields are used to focus attention in healing, energizing and meditative exercises.
Vitality, Energy and Spirit can also be defined in terms of three bodies: vitality is the flesh-and-blood body, energy is the electical body within the flesh-and-blood body and spirit is the ethereal body of consciousness within the electrical body. In yet another sense, vitality is the natural world, energy is the social world, and spirit is the psychological world.
Energy work is probably the most popular aspect of Taoism in both East and West, particularly through the wide spread use of exercise systems such as Tai Chi Chuan, Qigong and therapeutic techniques such as acupressure and massage. The practice of special exercises for health and longevity is extremely ancient in China, and many different Forms and Styles developed over the course of centuries.
Excerpt from Vitality Energy Spirit, a Taoist Sourcebook, Translated/Edited by Thomas Cleary