The Alchemy of Sexual Energy: Connecting to the Universe from Within by Mantak Chia.
Excerpt from the back cover:
"Taoists consider our sexual energy to be the creative force that we can use to regenerate the body's internal energy, but we must learn how to harness excess sexual energy and transform it into chi, or life-force energy. When we circulate the sexual energy in the Microcosmic Orbit, a continuous energy loop that runs up the spine and down the front of the body, we transform it into self-healing energy that can be stored in the organs and the three tan tiens - energy centers in the brain, the heart center, and the lower abdomen. The Alchemy of Sexual Energy shows how to transform this sexual energy into internal healing energy, building upon the Microcosmic Orbit practices discussed in Healing Light of the Tao.
The more we open the flow of our internal energy the more capable we are of connecting to the cosmic energy that exists outside ourselves in the universe. By learning to open the three tan tiens to the six directions, the Taoist practitioner combines mind power with the extension of chi to draw cosmic energy into the body. This energy, too, can be stored in the three tan tiens and used as needed for healing. When we learn to flow in this way with the energy of the Tao, life ceases to be a struggle."