Brain: "The Grand Design"
As a kind of interior universe, the brain might might qualify as a design as grand as that of the outer universe. There is as yet, anyway, no limit to how far into it we can go, just as there isn't limit to how far out of the universe we can go. This thought might be better suited to Chopra, but I couldn't resist.
Sam Harris might not have time to tell us much about the basic brain and how it produces our mental states, so a couple of resources might be helpful.
The first one is an NIMH article on brain geography, brief but detailed. http://www.ninds.nih.gov/disorders/brai ... _brain.htm
The second is an article from Time
on which areas of the brain are thought to produce our most common mental states.http://www.samharris.org/site/full_text ... ppy-brain/