Book excerpt: Evolving the Mind has two main themes: how ideas about the mind evolved in science; and how the mind itself evolved in nature. The mind came into physical science when it was realised, first, that it is the activity of a physical object, a brain, which makes a mind; and secondly, that our theories of nature are largely mental constructions, artificial extensions of an inner model of the world which we inherited from our distant ancestors. From both of these perspectives, consciousness is the great enigma. If consciousness evolved, however, it is in some sense a material thing whatever else may be said of it. Physics, chemistry, molecular biology, brain function and evolutionary biology - almost the whole of science - is involved, and there can be no expert in all these fields. So the style of the book is simple, almost conversational. The excitement is that we seem to be close to a scientific theory of consciousness.