The central discipline of the Yoga of Knowledge involves the systematic withdrawal of attention from the outer world, concentration of the attention within, and then a systematic stepping back even from these internal states of awareness. The seeker in the Yoga of Knowledge recognizes that he is not the body, he is not the specific life force, he is not the mind, he is not the ego-personality, and as he recognizes these things, he withdraws further as he works to turn the attention away from these ephemeral forms and forces to those things that are Eternal.
There are several stages of realization that come to the seeker as he progresses down this path. Sri Aurobindo describes them: “…he has arrived at realisation by knowledge of a pure, still, self-aware existence, one, undivided, peaceful, inactive, undisturbed by the action of the world. The only relation that this Self seems to have with the world is that of a disinterested Witness not at all involved in or affected or even touched by any of its activities.”
A further status makes the awareness even more remote from the world. “…at that is in the world is in a sense in that Self and yet at the same time extraneous to its consciousness, non-existent in its existence, existing only in a sort of unreal mind,–a dream therefore, an illusion.”
Sometimes the knowledge by identity leads the seeker to the recognition that this is the ultimate Self of his being, but in other cases, all sense of Self may actually be extinguished and there is then left a pure consciousness, aware, but unmoving and non-responsive to the forms and forces of the world action.
One can go from a state where the mental consciousness simply cannot define anything further and finds the status “unknowable” to an even further status where the mental consciousness blanks out and loses its entire ability to function. “It can even be realised by the mental being as a Nihil, Non-Existence or Void, but a Void of all that is in the world, a Non-Existence of all that is in the world and yet the only Reality.”
“To proceed farther towards that Transcendence by concentration of one’s own being upon it is to lose mental existence and world-existence altogether and cast oneself into the Unknowable.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 14, The Passive and the Active Brahman, pp. 384-385