In respect of the Art of War, we have:
- Estimation of quantity;
- Balancing of chances;
The Art of War (孫子兵法) is the oldest military treatise still in existence and the name may be more correctly translated as Military Methods. The book is primarily a strategy guide, although it does describe some tactical elements.
It appears to have been written during the Warring States period of Chinese history which was a time when warfare moved from the realm of the monarchs to that of professional generals with a consummate increase in effectiveness and death.
Sun Tzu (孫子) was alive during the 6th century BCE, although there is some controversy over which bits of the text are directly attributable to him, if any. When alive Sun Tzu was working for King Wu (in contemporary accounts he is referred to as Sun Wu, Tzu being an honorary title bestowed upon him later).
Whether or not he actually wrote every word that is in the standard text doesn't really matter for anybody wishing to study its teachings. The strategies and tactics described must stand or fall on their own merits.
The text I have used is based on Lionel Giles' 1910 translation, although I have cut the annotations and the lengthy preamble. In a few places I have changed the wording from Giles' and I've also changed the layout this translation is normally presented in.