Most philosophical discussions on human consciousness begin with two frequently made confessions, namely that consciousness is (a) deeply familiar; and (b) deeply mysterious. David Chalmers describes it as follows:

Conscious experience is at once the most familiar thing in the world and the most mysterious. There is nothing we know about more directly than consciousness, but it is far from clear how to reconcile it with everything else we know […]. We know consciousness far more intimately than we know the rest of the world, but we understand the rest of the world far better than we understand consciousness.

(1996: 3; see also Chalmers 2010 )