The common man is aware of himself only when modifications arise in the intellect (vijnanamaya kosa); these modifications are transient they arise and set. Hence the vijnanamaya (intellect) is called a kosa or sheath. When pure awareness is left over it is itself the Chit (Self) or the Supreme. To be in one's natural state on the subsidence of thoughts is bliss; if that bliss be transient - arising and setting - then it is only the sheath of bliss (Anandamaya kosa), not the pure Self.
What is needed is to fix the attention on the pure 'I' after the subsidence of all thoughts and not to lose hold of it. This has to be described as an extremely subtle thought, else it cannot be spoken of at all, since it is no other than the Real Self.
Who is to speak of it, to whom and how?
-- Talk 624, 4th February 1939.