It doesn’t come from anywhere, but is everywhere, pervading the whole universe as its essence. Consciousness is you, and you are consciousness. All phenomena appear to be just that – appearances; but in reality, being the expression of consciousness, they are only consciousness. There is no other reality.
Realization of witness consciousness is not brought about by anything or ‘anybody’. Consciousness does not perform any function, and there is nothing beyond or other than it. Finally, only intuition can nudge one towards it.
“I am the Witness-Self; I am the basis of all experience; I am the light that makes experience possible.” Yoga Vasishta.