The self means in spiritual sense the source of the whole existence.

People think  the  ego is the self .  When one considers the mind to the physical entity then  it becomes ego.  The self means in spiritual sense the source of the whole existence. By limiting the self to the physical entity is cause of all sorts of doubts and confusion.

Science and modern thinkers limit the self to the ego.  The ego, body world, intellect are division created out of consciousness.  They all appear together and disappear together. All the energy, thought, world, ego body whatever accumulated dross and conditioning can be summed up and called with single word as mind, because they all exist when the mind exist, without the mind all these cesses to exist. Therefore, there is only a need to discriminate between mind and no mind experiences.  All the intellectual analysis is not required because it is beyond intellectuality.    

We have to use less word to get the truth.

That which one knows best in the waking, that which is nearest to him, that of which he can never be free, whose existence is supremely certain, is his consciousness which is the self. One may doubt anything else but he directly perceives his-self, which is consciousness.

Hence one has to begin the pursuit of truth with the study of consciousness, not, as is mistakenly done by theologians, metaphysicians, with the supposed Absolute.

All gold ornaments with different shapes are made of this same single material, so to explain the nature of the unknown self, one has start with something known and familiar, viz. consciousness, which one has in the three states, and proceed step by step from that onwards. One knows his -self as physical but it is mistake.  If one considers the self is physical then it becomes ego. The self is not the ego but the knower of the ego. This soul/self   is not physical but it is consciousness, which holds the whole physical existence. After knowing the fact that this consciousness is the self, one becomes aware the consciousness is ultimate truth.

All the three states product of the consciousness which should enable anyone to understand everything [all the three states] is consciousness. Moreover everyone has and knows this consciousness; therefore it is a universal datum. It is something which everybody can grasp, not merely some occultist or mystic; therefore there is no mystery-mongering in the study of truth.