When one-pointed awareness on the prolonged inner sounds of different musical instruments, such as stringed, wind and percussion, is gradually established, in the end the body becomes the supreme space.
By repetition of all the gross letters of the bija mantras successively, including the 'M', (and meditating thus! on the void within each sound, one verily becomes Shiva.
All the directions should be contemplated upon simultaneously in one's own body as space or void. The mind (too) being free from all thoughts becomes dissolved (in the vacuous space of consciousness).
One who contemplates simultaneously on the void of the back (spinal column) and thel void of the root becomes void-minded (completely free of all thought constructs or Vikalpas) by that energy which is independent of the body.
By steady contemplation on the void of the back (sushumna), the void of the root and the void of the heart simultaneously, there arises the state of nirvikalpa, which is free from thought constructs.