The riddle of consciousness materialism and physicalism - a tale of two isms functionalism neuroscience Einstein and the identity theory how unified is consciousness? state space the refutation of physicalism the problem of perception Berkeley, Russell and the inscrutability of matter states and observables the paradox of Schrodinger's cat quantum mechanics and the conscious observer could the brain be a quantum computer? time and mind Descartes's legacy - mind and meaning, science and scepticism.