The paper begins with a general introduction to the nature of human consciousness and outlines several different philosophical approaches. A critique of traditional reductionist and dualist positions is offered and it is suggested that consciousness should be viewed as an emergent property of physical systems. However, although consciousness has its origin in distributed brain processes it has macroscopic properties - most notably the `unitary sense of self', non-deterministic free will, and non-algorithmic `intuitive' processing - which can best be described by (...) quantum-mechanical principles. (shrink)