Besides, one has to imagine that the Self can have the attribute of coming into contact with others, which idea is repugnant to the Vedas and Smirtis; for such are the Vedic and Smirti texts: “Unattached, for It is never attached” (Brh.III.ix.26) “It is unconnected, and is the supporter of all” (B.G. XIII.14) Moreover, since logic demands that a thing that has attributes, and is not of a different category, can come into contact with another having attributes, therefore it is illogical to hold that the Self which is attributeless, undifferentiated, and distinct from everything else, can come into contact with anything whatsoever that does not belong to the same category. Hence if the Self is the witness of all cognitions, then and not otherwise is established the idea that the Self, which is an effulgence that is in reality eternal and undecaying knowledge, is Brahman. Therefore the expression pratibodha videtam (known with every state of awareness) has the meaning as explained by us.(from Shankara’s commetary on Kena Up. II.4)
Here we have presented an idea similar to that of Aristotle in De Anima namely that only things of the same sort can interact. That book is not to hand at the moment so I will search out that citation later. Unchanging and present in all states of awareness means that it is identified with pure consciousness or Brahman and therefore the highest state of consciousness is spoken of as sahaj samadhi or natural samadhi.
Ramana Maharshi defined it as:
Sahaja samadhi is a state in which the silent awareness of the subject is operant along with (simultaneously with) the full use of the human faculties.Ramana in the meditation hall sitting on his couch reading the newspaper, chatting with the devotees, ‘it says here’, never loses contact with the Self.