There is no asana like Siddha, no kumbhaka like Kevala, no
Mudra like Khechari, and no laya ( absorption of the mind) like nada.
(Khechari Mudra, literally roaming through space, is
described in the Gheranda Samhita as follows in verses 25 to 28 of the third
chapter: ’
‘ Cut the lower tendon of the tongue and move the tongue
constantly; rub it with fresh butter, and draw it out ( to lengthen it) with an
iron instrument. By practicing this always, the tongue becomes long and when it
reaches the space between the eyebrows, then khechari is accomplished. Then
(the tongue being lengthened) practice turning it up and back so as to touch
the palate, till at length it reaches the holes of the nostrils opening into
the mouth. Close those holes with the tongue (thus stopping inspiration), and
gaze on the space between the eyebrows. This is called khechari. By this
practice there is neither fainting, for hunger, nor thirst, nor laziness. There
comes neither disease, nor decay, nor death. The body becomes divine.’).
(Nada is the inner
mystical sound. Verse 79 to 101 of the fourth chapter describes it in great
detail with a variety of similes. Yoga is defined as control over the
aberrations of the mind. In order to control the mind it is necessary that it
should first be absorbed in concentration of some object, then it is gradually
withdrawn from that object and made to look with in one own self. This is where
the yogi is asked to concentrate upon the inner mystical sounds. The mind is
like a serpent, forgetting all its unsteadiness by hearing Nada, it does not
run away anywhere, Gradually as Nada Becomes latent so does the mind along with
it. The rate as Nada becomes latent so does the mind along with it. The fire,
catching the wood, is extinguished along with it (after burning it up) ; and so
the mind also so, working with Nada,
becomes latent along with it).