In the early 1600s some of Japan's samurai who were not vassals of fief clan lords traveled about the country challenging other samurai to fight duels to the death as their way of training-a shogunate approved custom known as shugyosha [shuu-g'yoh-shah] or "samurai-in-training," The shugyosha who was to become the most famous samurai in Japan's history was a young man named Musashi Miyamoto, who fought his first duel when he was 13 years old. By the time Miyamoto was 28 he had killed over 60 other samurai in death duels, a dueling record that has never been equaled in any country where duels were a common practice. Somehow, at a very young age, Miyamoto had developed a fighting technique based on 13 principles and 13 practices that made him invincible-simply unbeatable by a single or multiple opponents. Miyamoto then retired from killing, but continued roaming the country, teaching his way of sword-fighting at the dojo of fief lords and staging demonstrations. The principles and practices Miyamoto created were based on the fundamentals of Zen: recognizing the difference between illusion and reality; between the irrational and rational; between the impractical and practical; between weakness and strength, etc. In addition to the story of Zen in India, China, Korea and Japan, I have identified and described the 26 principles and practices Miyamoto created and reformulated them as guidelines for the most desirable mindset and behavior of all categories of people, from athletes, businesspeople, educators, parents and politicians to students.