Brain scientists will tell you that the greatest problem facing human biology, and perhaps all of science, is cracking the code of consciousness. It means solving the long-intractable brain-mind conundrum: How does our material brain--the most complex physical system known--produce our immaterial but vital sense of awareness? Neuroscientists and philosophers argue fiercely about how to solve the riddle and whether it is even solvable. Some say consciousness is illusory. (Try to counter that one--a real headache.) Others say consciousness exists but at too complex a level for humans to fathom, like quantum mechanics is for monkeys. Still others believe consciousness will yield its secrets only when we discover new physical brain laws that could reveal its creation.