Miyamoto Musashi (1584-1645), Japanese samurai, wrote Go Rin No Sho a few weeks before his death. It contains 5 chapters dealing with the martial arts. Books cover the nature of Ground, Water, Fire, Wind and the Void as they pertain to fighting. Musashi gives these precepts in the first chapter (Victor Harris translation):
Do not think dishonestly.
The Way is in training.
Become acquainted with every art.
Know the Ways of all professions.
Distinguish between gain and loss in worldly matters.
Develop intuitive judgement and understanding for everything.
plus many more translations, so do a search at your favourite bookstore.
The book is a valuable discussion of strategy, even if it wasn't likely written by one person (there is even some question over whether there was one Miyamoto Musashi).
Very pragmatic and effective. Here is a quote cited in EveryoneShouldBeaMethodologist:
Musashi [...] commands the student of swordplay to always remember that his goal is to kill his enemy. He is not learning to parry, thrust, spin, whatever. He is not practicing a high block or a low feint. He is trying to kill his enemy. All the individual practices are means to that end.