When mind/ duality appears through ignorance, then one sees another; but when everything becomes identified with the consciousness, one does not perceive another even in the least in the midst of duality, because he is fully aware of the fact that the whole experience of diversity is created out of consciousness.
In that state when one realizes all as identified with the consciousness, there arises neither delusion nor sorrow, in consequence of the absence of duality. Consciousness, which is the Self of all, is verily consciousness.
This waking experience, though an object of our daily experience and serving all practical purposes, is, like the dream, of the nature of non-existence, inasmuch as it is contradicted the next moment.
The dream experience is unreal in waking, whereas the waking experience is absent in dream. Both, however, are non-existent in deep sleep which, again, is not experienced in either.
Thus all the three states are unreal; but their witness the reality behind them is, beyond all attributes, eternal, one, and is Consciousness itself.