Part I: Chapter II / II – (iv)

a) Plexuses or Chakras

Wherever several nerves, arteries or veins interlace each other, that point or center is called a plexus. Similarly, there are plexus or centers of vital forces in the Suksham or subtle nadis and these are called chakras or padmas. The nadis are the astral tubes made up of astral matter, and serve as passages for subtle pranas through which they operate in the subtle body as do the nerves, arteries and veins in the gross physical body. All these subtle tubes or nadis spring from Kanda or the center where the Sushmana Nadi meets the Muladhara Chakra at the base of the spine. Of these Nadis, Ida, Pingala and Sushmana are the most important. All three nadis are within the spinal cord. Ida and Pingala or on the left and right side respectively of the Sushmana or Sukhman.

The Ida (Chandra canal) flows through the left nostril and the Pingla (Surya canal) through the right. Breath generally flows through each for about two hours alternately. But when it flows through the Sushmana (Agni canal), the mind becomes steady. This steadiness or Unmani Avastha, as it is called, is the highest state in Raja Yoga, for in this state there is wonderful meditation. The practice of Pranayam is necessary for purification of the nadis, as with impurities in them, the breath cannot pass through the middle nadi.

Gross prana travels in the nerve of the physical body, but the subtle or physical prana moves in the astral tubes (nadis). The breath is an external effect of the manifestation of the gross prana.

There is a very close and intimate connection between the gross and the subtle prana. If the mind and the prana cease to vibrate, no thought-wave will arise.

The mind functions through prana, it is from prana (life) that everything proceeds.

Chhandogya Upanishad,
Chapter V, Shalokas 14-15

When prana departs from the body, all organs cease to function, for in the body there is no greater force than bio-energy (prana).