The Origin of Consciousness in the Breakdown of the Bicameral Mind by Julian JaynesRead about the other entries on the list.
This is one of the best titles to drop when asked what you're currently reading, and also a revealing, radical study of our divided brains. According to Jaynes, people who hear voices (be they mystics or schizophrenics) may just be listening to one side of the brain talking to the other on a delayed loop. Something to think about next time you find yourself thinking out loud, or just thinking period.
--Marshal Zeringue