九变
Adapt endlessly — no rule is absolute; weigh advantage and disadvantage together, and rely not on the enemy not coming but on your own readiness to meet him.
- What this chapter says
- Key lines
- Applied today
- Related stratagems
- Chapters that share ground with this one
What this chapter says
Variation in tactics is the doctrine of flexibility: the general must adapt to circumstances and not be bound by rigid rules. There are roads not to be followed, armies not to be attacked, towns not to be besieged, positions not to be contested, and even commands of the sovereign not to be obeyed — when the situation demands it. The wise leader always blends consideration of advantage with consideration of disadvantage: seeing the gain in a setback keeps him steady, and seeing the danger in a gain keeps him safe. Above all comes preparedness: do not count on the enemy not coming, but make yourself ready to receive him; do not count on his not attacking, but make your position unassailable. Five faults can destroy a general — recklessness, cowardice, a hot temper, an obsession with honour, and over-attachment to his troops — because each is a rigidity an enemy can exploit.
Key lines
From 十一家注孫子, the Eleven Commentators edition. The Chinese is verbatim from that text; the English beneath each is ours.
- 曹操 在利思害，在害思利，當難行權也。 In gain, think of the harm; in harm, think of the gain — that is how a hard choice is weighed.
- 李筌 害彼利此之慮。 Weighing what harms him against what benefits us.
- 賈林 雜一爲親，一爲難。言利害相參雜，智者能慮之慎之，乃得其利也。 'Mixed' — the one is the near thing, the other the hard thing. It means gain and harm are interwoven; the wise man can weigh them and be careful of them, and so gets the gain.
- 王晳 將通九變，則利害盡矣。 Let the general master the nine variations and gain and harm are exhausted.
- 張預 智者慮事，雖處利地，必思所以害；雖處害地，必思所以利。此亦通變之謂也。 When the wise man weighs a matter, though he stands on advantageous ground he must think what could harm him; though he stands on harmful ground he must think what could serve him. This too is what is meant by mastering change.
- 梅堯臣 所恃者，不懈也。 What one relies on is not slackening.
- 賈林 此五種之人，不可任爲大將，用兵必敗也。 Men of these five kinds cannot be given command of an army; used in war they are certain to be beaten.
- 梅堯臣 當慎重焉。 One should be careful and grave about it.
- 張預 言須識權變，不可執一道也。 It means one must understand adaptation, and not hold rigidly to a single way.
Applied today
No playbook fits every case — the best leaders bend the rules to the situation, and even push back on an instruction from above when the facts on the ground demand it. Rigidity in any single direction is the exploitable flaw.
Plan for what a rival or the market could do, not for the comfortable assumption that they won't — resilience comes from a position that holds up even under attack. And weigh every upside against its hidden downside before committing.