I believe that the most intriguing thing in the world, be sides the world itself, is the human brain. Moreover, I am sure that a coherent natural philosophy will only be possible once we have understood how the brain, itself an object of physics, generates the description of the physical word. Therefore a book on the brain, be it the fly's or the mouse's brain, needs no justification. It is important, however, to point out the limits of its ambi tions. The first three Chapters are introductory and are written in a lighthearted philosophical vein. An idea is introduced that turns up repeatedly...