6. Weak Points and Strong
That is, as Wang Hsi says: "they predominate alternately."
the four seasons make way for each other in turn.
Literally, "have no invariable seat."
Cf. V. ss. 6. The purport of the passage is simply to illustrate the want of fixity in war by the changes constantly taking place in Nature. The comparison is not very happy, however, because the regularity of the phenomena which Sun Tzu mentions is by no means paralleled in war.