Security against defeat implies defensive tactics; ability to defeat
the enemy means taking the offensive.
For 不可勝 I retain the sense which it undoubtedly bears in §§ 1–3,
in spite of the fact that the commentators are all against me. The
meaning they give, “He who cannot conquer takes the defensive,” is
plausible enough, but it is highly improbable that 勝 should
suddenly become active in this way. An incorrect variant in the
_Yü Lan_ is 不可勝則守可勝則攻.