The Book of Five Rings

Miyamoto Musashi is an interesting fellow. A ronin (masterless samurai), he roamed feudal Japan in the early 17th century regularly fighting scores of men alone, and winning. Late in life, he dictated the secrets he had learned throughout his travels, calling it The Book of Five Rings. Each of the first four rings (Earth, Water, Fire, Wind) deals with a different aspect of overcoming adversity, while the last ring reveals what he saw as the innermost tenet of his philosophy. I was introduced to this subject by a rather elegant 5k entry. Vote here.