The Conscious Mind Book by David Chalmers

In The Conscious Mind: In Search of a Fundamental Theory (1996), David J. Chalmers argues that consciousness is an irreducible, fundamental feature of the universe that cannot be explained solely by physical processes. He famously distinguishes between the "easy problems" of cognitive science—explaining behaviors and information processing—and the "hard problem," which is explaining why these processes are accompanied by subjective experience.