The Unfettered Mind (不動智神妙録, Fudōchi Shinmyōroku) 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.
All three chapters/essays are addressed to the samurai class, and all three seek to unify the spirit of Zen with the spirit of the sword.
Of the three essays in the treatise, two were letters:
- Fudōchishinmyōroku, "The Mysterious Record of Immovable Wisdom", written to Yagyū Munenori, head of the Yagyū Shinkage-ryū school of swordsmanship and teacher to two generations of shōguns; and
- Taiaki, "Annals of the Sword Taia", (太阿記) written perhaps to Munenori or possibly to Ono Tadaaki, head of the Ittō school of swordsmanship and an official instructor to the shōgun's family and close retainers.
Individually and broadly speaking, one could say that Fudōchishinmyōroku deals with technique, how the self is related to the Self during confrontation, and how an individual may become a unified whole.
Taiaki deals more with the psychological aspects of the relationship between the self and the other.
Between these, Reiroshu, "The Clear Sound of Jewels", deals with the fundamental nature of humans: how a swordsman, daimyō – or any person, for that matter – can know the difference between what is right and what is mere selfishness, and can understand the basic question of knowing when and how to die.
Fudōchishinmyōroku (The Mysterious Record of Immovable Wisdom) is divided into the following sections:
- The Affliction of Abiding in Ignorance
- The Immovable Wisdom of All Buddhas
- The Interval into Which Not Even a Hair Can Be Entered
- The Action of Spark and Stone
- Where One Puts the Mind
- The Right Mind and the Confused Mind
- The Mind of the Existent Mind and the Mind of No-Mind
- Throw the Gourd into the Water Push It Down and It Will Spin
- Engender the Mind with No Place to Abide
- Seek the Lost Mind
- Throw a Ball into a Swift Current and It Will Never Stop
- Sever The Edge Between Before and After
- Water Scorches Heaven, Fire Cleanses Clouds
Sōhō refers to many poems and sayings, including those of:
- Bukkoku Kokushi (1256–1316): A Buddhist priest
- Saigyō (1118–90): A Shingon priest of the late Heian period famous for his wanderings and highly admired as a poet
- Mencius (372–289 BC): A Chinese philosopher, the most famous Confucian after Confucius himself
- Jien (1155–1225): Also widely known by the name Jichin; a poet and monk of the Tendai sect
- Mugaku (1226–86): A Chinese priest of the Linchi (Rinzai) sect, invited to Japan by Hojo Tokimune in 1278
- Shao K'ang-chieh (1011–77): A scholar of the Northern Sung Dynasty
- Zhongfeng Mingben (1263–1323): A Chinese Zen priest of the Yuan Dynasty
- The Pi Yen Lu, a collection of Zen problems, sayings and stories of the patriarchs
- The Ise Monogatari, a work of the ninth century
- The Doctrine of the Mean
- The Golden Light Sutra
- Li Po (Li T'ai Po, 701–62): One of the great poets of T'ang period China
- Ippen Shonin (1239–89): Founder of the Jodo sect of Pure Land Buddhism
- Hotto Kokushi (1207–98): A monk of the Rinzai sect who traveled to Sung China in 1249
- The Namu Amida Butsu, "Homage to the Buddha Amitabha"
- Kogaku Osho (1465–1548): An Arinzai monk who taught Zen to the Emperor Go-Nara
- The Fan-i Ming-i Chi, a Sung Dynasty Sanskrit-Chinese dictionary
- Bodhidharma: The first patriarch of Ch'an (Zen) Buddhism in China; he is said to have arrived in that country from India in either A.D. 470 or 520
- Ta Chien (637–713): Commonly known as Hui Neng; a pivotal figure in the development of Zen
- Daio Kokushi (1234–1308): A monk of the Rinzai sect who studied Buddhism in China
- Daito Kokushi (1282–1337): A follower of Daio Kokushi regarded to be the founder of Zen at Daitokuji
- Nai Chi Hsu T'ang (1185–1269): Also known as Hsu T'ang Chih Yu; a Chinese monk of Linchi Buddhism
- The Cheng Tao Ko, an early treatise on Zen
- Takuan Soho, translated by William Scott Wilson, The Unfettered Mind – Writings of the Zen Master to the Sword Master, p. 3.