This article is from the Magick Tantra FAQ, by Tyagi Nagasiva firstname.lastname@example.org, Catherine Yronwode email@example.com with numerous contributions by others.
This is spoken of in almost every branch of sex-magic
and sex-religion. In some schools of tantra yoga, the
ascent of subtle energies up the spine and through a
series of energy points on the body (chakras) is
envisioned and experienced -- especially by those whose
teaching style is heavily influenced by kundalini yoga.
As applied to tantra yoga, this kundalini-influenced
vision of sexual union presents the energy as rising
upward around each person's spine in twin currents (ida
and pingala) surrounding a central core (sushumna), then
joining at the top (crown chakra), and joining in union
with the kundalini in the partner's crown chakra. Western
sex religionists and sex-magicians also refer to such
subtle energies, but they are envisioned in different ways.
The 19th century writer Paschal Beverly Randolph presented
an elaborate electro-magnetic and gender-specific model
for the exchange of energy between two people who were
engaged in frontal-contact coition. The early 20th century
writer George Washington Savory experienced deep spiritual
bliss and union with the divine from the aetheric energies
he received when nursing at his wife's breast; she in turn
described the nurturing and healing energy embodied in his
semen. Followers of the 20th century psychologist Wilhelm
Reich perceive the flow of "orgone" energy aroused during
sexual contact "streaming" up the frontal surface of the
body. Taoist sexual alchemists describe the "circulation
of chi" (vital energy) in the body at different stages of
arousal, culminating with the upward passage of chi along
the "meridian" system, through "gates" and into the head.
Direct experience leads many practitioners of most forms
of Western sacred sex to describe a state in which their
bodies seem to physically merge, blend, or become one with
each other, with a free flow of energetic sensation shared
between their central cores.