Aldous Huxley called humankind's basic trend toward spiritual growth the perennial philosophy. In the view of James Austin, the trend implies a perennial psychophysiology - because awakening, or enlightenment, occurs only when the human brain undergoes substantial changes. What are the peak experiences of enlightenment? How could these states profoundly enhance, and yet simplify, the workings of the brain? Zen and the Brain presents the evidence.