Unfettered Mind
is a three-part treatise on Buddhist philosophy and martial arts written in the 17th century by Takuan Sōhō, a Japanese monk of the Rinzai sect. The title translates roughly to "The Mysterious Records of Immovable Wisdom". The book is a series of three discourses addressed to samurai but applicable to everyone who desires an introduction to Zen philosophy, the book makes little use of Buddhist terminology and instead focuses on describing situations followed by an interpretation. Its contents make an effort to apply Zen Buddhism to martial arts.