[The heading means literally "The Nine Variations," but as Sun Tzŭ does
not appear to enumerate these, and as, indeed, he has already told us
(V §§ 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 vary 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.]