In ancient concepts
of the subtle body, one of the vertical channels (nadi).
The subtle body is a physiological system that is thought to
exist on a separate level than coarse matter yet has certain similarities with
it.
It's shown as a series of six psychic centers (chakras) that
run nearly parallel to the spine and are joined by three parallel vertical
channels.
The corporeal abodes of the two divine principles, Shiva
(consciousness) and Shakti (power)—the latter as the latent spiritual force
known as kundalini—are envisioned in the shape of a coiled serpent above and
below these centers.
The ultimate goal of yoga that focuses on the subtle body is
to awaken the kundalini and move it up via the chakras to Shiva's home.
The combination of Shiva and Shakti in the aspirant's body
reflects the movement of these divine energies in the macrocosm, and it is
through this union that the aspirant achieves happiness and complete soul
freedom (moksha).
The sushumna is the most essential of the three vertical
channels in the subtle body—the other two are the ida nadi and the pingala
nadi—and it is the center of the three.
During the aspirant's spiritual exercises, the rising
kundalini wakes and straightens, penetrating through the chakras on its route.
The sushumna is usually blocked where it joins the chakras,
which prevents energy from flowing freely through it.
The route for the kundalini to climb to Shiva's dwelling and
effect the union of Shakti and Shiva that would bring ultimate enlightenment
has been opened when the chakras have been pierced and opened by the rising
kundalini.
See Arthur Avalon's (Sir John Woodroffe's) Shakti and
Shakta, 1978; Philip S. Rawson's The Art of Tantra, 1973; Swami Agehananda
Bharati's The Tantric Tradition, 1975; and Douglas Renfrew Brooks' The Secret
of the Three Cities, 1990 for further details.
