This is a translation of an important classic on Zen swordfighting. Yagyu Munenori was so widely renowned that he was appointed official sword instructor to two Tokugawa shoguns. (The position was always coveted by Miyamoto Musashi, but he never succeeded in gaining the post). Yagyu's style is known as the Shinkage-ryu style, for centuries the official style of the Tokugawa dynasty. His spiritual mentor was Zen priest Takuan.