Sun Zi – The Art of War

Chinese strategy explained : know yourself and the ennemy, use deception, spies, and "win with ease". Tr. Giles (en, annotated) and Amiot (fr).

Introduction
I. Laying Plans
II. Waging War
III. Attack by Stratagem
IV. Tactical Dispositions

V. Energy
VI. Weak Points and Strong
VII. Maneuvering
VIII. Variation in Tactics
IX. The Army On The March

X. Terrain
XI. The Nine Situations
XII. The Attack By Fire
XIII. The Use of Spies

Variation In Tactics

The heading means literally "The Nine Variations," but as Sun Tzu does not appear to enumerate these, and as, indeed, he has already told us (V SS. 6-11) that such deflections from the ordinary course are practically innumerable, we have little option but to follow Wang Hsi, who says that "Nine" stands for an indefinitely large number. "All it means is that in warfare we ought to very our tactics to the utmost degree... I do not know what Ts`ao Kung makes these Nine Variations out to be, but it has been suggested that they are connected with the Nine Situations" - of chapt. XI. This is the view adopted by Chang Yu. The only other alternative is to suppose that something has been lost–a supposition to which the unusual shortness of the chapter lends some weight.

Sun Zi VIII. 25.