Water, fire, wood, metal, earth.
are not always equally predominant;
That is, as Wang Hsi says: 迭相克也 “they predominate alternately.”
the four seasons make way for each other in turn.
Literally, “have no invariable seat.”
There are short days and long; the moon has its periods of waning and
waxing.
Cf. V. § 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 Tzŭ mentions is by no means
paralleled in war.