Miyamoto Musashi 
The Book of Five Rings: The Classic Text of Samurai Sword Strategy 

The Book of Five Rings is a text on kenjutsu and the martial arts in general, written by the swordsman Miyamoto Musashi circa 1645. There have been various translations made over the years, and it enjoys an audience considerably broader than only that of martial artists: for instance, some business leaders find its discussion of conflict and taking the advantage to be relevant to their work. The modern-day Hyōhō Niten Ichi-ryū employs it as a manual of technique and philosophy.