Yajñavalkya was asked how that Self is to be conceived, to which he responded:
You cannot see the seer of seeing. You cannot hear the hearer of hearing. You cannot think the thinker of thinking. You cannot understand the understander of understanding. He is your Self, which is in everything. Everything else is irrelevant.
There is no possible way to exhaustively describe or define that supreme Reality. One must simply realize it, and in this state of the fully awakened consciousness of Self (atman) or brahman one could doubtlessly declare, as did Yajñavalkya, "I am the Absolute (the Whole)." This ultimate essence of life is described as being pure Selfhood, that is, the knower who is unknowable, the seer who cannot be seen, and so forth, as being the One - transcendent of all multiplicity as being pure consciousness, that is, consciousness that is free from any enslavement or limitation within the subject-object duality of ordinary experience.