The Book of Five Rings is required reading for any serious martial artist. it was written by Miyamoto Musashi, Japans greatest swordsman. In it he describes the inner journey of a martial artist to mastery. "All men are the same, accept for their belief in themselves" I prefer the version that is translated by Steve Kaufman. He is a martial artist and translates it from that point of view; so it is not a book on business strategy as Musashi is sometimes used.