Vijnana Bhairava Tantra · Dharana 20 · Verse 43
Body in boundless space
Feel the body first, so that you have somewhere to begin. Then let space run through it and out in every direction at once, not only forward, not only above. Stay until the sense of the body as a closed container begins to loosen.
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Contemplate space spreading in every direction within your own body, all at once. The mind falls free of thought, and everything becomes space.