"Consciousness is a scientific problem that is unlike any other. Our own consciousness, as Descartes noted, is the most indubitable feature of our existence. It is the most precious one, as well: consciousness is life itself, and for most people having their bodies kept alive in a vegetative state is no better than dying." -- Steven Pinker, Professor of Psychology, Harvard University

Consciousness is also a unique scientific problem in other ways. There is no general agreement about the definition of the subject of study. Opinions are divided about how - with which methods - it should be studied. And nobody can know for sure which answers could possibly be relevant. For many decades it was forgotten by science, buried underground by the regime of behaviourism and cognitive science, but now it has arisen again and has become a hot topic in circles working at the frontier of science.