Kiai-jutsu, the Japanese art of the martial shout, is where this book starts. It is not where it ends. Human beings have been giving their voice power for longer than any single martial art has existed. Power to commit to an action, power to frighten an enemy, power to unite a crowd, power to invoke something larger than themselves, power to comfort, and, in more traditions than you’d expect, power to heal. That’s the actual subject here. Kiai-jutsu is the doorway. What’s on the other side is bigger.