Book excerpt: After spending two years in bed with Lyme disease, Steven Kotler had lost everything: his health, his job, his girl, and, he was beginning to suspect, his mind. Kotler, not a religious man, suddenly found himself drawn to the sport of surfing as if it were the cornerstone of a new faith. Why, he wondered, when there was nothing left to believe in, could he begin to believe in something as unlikely as surfing? What was belief anyway? How did it work in the body, the brain, our culture, and human history? With the help of everyone from rebel surfers to rocket scientists, Kotler undertakes a three-year globetrotting quest. The results are a startling mix of big waves and bigger ideas: a surfer's journey into the biological underpinnings of belief itself.