This is a volume of thoughtful essays by a group of scientific leaders from physics, cognitive psychology, cognitive science, the philosophy of science, artificial intelligence, and brain physiology. It addresses fundamental issues such as, in the words of one of the contributors, 'How a mind resides in a brain.' The essays are set in the framework of the evolving scientific concept of complex adaptive systems, the basis for which is laid in an impressive essay by another Nobelist, physicist Murray Gell-Mann.