What is consciousness: physical or nonphysical?

The following is an excerpt from a samvaad (dialogue) session with Acharya Prashant.

Questioner: Acharya Ji, whenever you’ve been asked what is consciousness, you’ve simply said that all that is mind-stuff is consciousness. A question that is not relevant to me personally. But still, I thought like material stuff is visible, it can be touched. So, that is one thing. The other thing is the Ātman; which is beyond knowledge and all. This consciousness thing is somewhere in between. So, I mean many people have asked this foolish question. Where does consciousness reside and everything? I’m not trying to ask that but, still like what is it? What constitutes it. How does it work?

Acharya Prashant: See, how does this material body come to be conscious; is a great mystery. There is no answer to that. You can not similarly answer the question; How does this material body come to become unconscious? Or, how does the Prāṇa leave the body? Ramana Maharishi used to explain this by saying that there is a ‘Jada-Chetan Granthi’ somewhere in the body, where the ‘Jadata*’ which is the ‘material body’ meets ‘consciousness–pure consciousness.’ And he used to say that, “That *Granthi, that knot is the cause of all human suffering. So, you have to sever this knot, you have to cut that knot somewhere.”