虛實

致人而不致於人 — 'compels others and is not compelled by others.' This six-character phrase is the thesis of the entire chapter. 致 means to cause to come, to summon, to compel. The skilled commander controls the initiative: the enemy reacts to him, never the reverse.

佚 (yi) — 'rested,' 'at ease.' An alternate form of 逸. Contrasted with 勞 (lao), 'exhausted.' The advantage of arriving first is not merely positional — it means your troops are fresh, fed, and deployed, while the enemy arrives winded and disorganised.

利之也...害之也 — 'it is advantage...it is harm.' These two levers — offering gain and threatening damage — are the only tools needed to control the enemy's movement. Every manoeuvre reduces to one or both.

出其所不趨趨其所不意 — 'appear where he cannot rush to; strike where he does not expect.' 趨 means to hasten, to rush. The enemy cannot rush to defend every point; by threatening unexpected locations, you force him into reactive, exhausting redeployment.

千里 (a thousand li) — approximately 500 km in Warring States measurements. The point is not literal distance but the principle: even long marches need not be exhausting if the route avoids enemy contact.

司命 (si ming) — 'arbiter of fate,' literally 'master of destiny.' In Chinese mythology, the Siming was a celestial deity who controlled life and death. Sunzi borrows the term: the commander who masters emptiness and fullness holds the enemy's life in his hands.

微乎微乎...神乎神乎 — rhetorical exclamations rare in Sunzi's usually austere prose. 微 means subtle, minute, imperceptible; 神 means spirit-like, divine, uncanny. The paired exclamations mark this passage as a climactic statement.

沖其虛 — 'strike at his emptiness.' 沖 means to rush at, to charge. 虛 is the empty, undefended point. This is the core tactic of xu-shi warfare: concentrate your fullness against the enemy's emptiness.

攻其所必救 — 'attack what he must rescue.' This is the principle behind all diversionary attacks: threaten something the enemy cannot afford to lose (his capital, his supply line, his sovereign), and he must come out of his fortifications to defend it.

畫地而守之 — 'draw a line on the ground and defend it.' A vivid image of minimal defence — not even proper fortifications, just a line in the dirt. The point: if you have successfully misdirected the enemy, you need no walls.

乖其所之 — 'deflect him from where he is going.' 乖 means to deviate, to go astray, to misdirect. You make the enemy lose his sense of direction and purpose, so he no longer knows how to bring his force to bear.

形人而我無形 — 'impose form on the enemy while I remain formless.' This is the xu-shi principle in action: make the enemy reveal his dispositions (by probing, feinting, threatening) while keeping your own intentions invisible. The enemy who is 'formed' is predictable; you, being 'formless,' are not.

我專為一敵分為十是以十攻其一也 — the mathematics of concentration. If the enemy must spread his forces across ten possible points of attack, and you concentrate everything at one point, you achieve local 10:1 superiority even if your total forces are equal. This principle — achieving local superiority through concentration — is fundamental to all subsequent military theory, from Napoleon to Clausewitz.

約 (yue) — 'hard-pressed' or 'constrained,' literally 'restricted.' The enemy at the point of contact faces overwhelming numbers and has no room to manoeuvre.

寡者備人者也衆者使人備己者也 — the chapter's key strategic insight distilled into a single antithesis. The 'few' (the side at a disadvantage) are those forced to defend against the enemy's initiative. The 'many' (the side at an advantage) are those who seize the initiative and force the enemy to defend. Numbers are not absolute — they are a function of who holds the initiative.

越人之兵 — 'the troops of Yue.' Yue (越) was a southeastern state (modern Zhejiang/Fujian) that famously defeated its rival Wu in 473 BC. Sunzi is traditionally associated with Wu. This reference to Yue's troops has been taken as evidence both for and against the traditional attribution of the text to Sun Wu.

勝可為也 — 'victory can be manufactured/created.' Contrast this with Chapter 4's statement that 勝可知而不可為 ('victory can be foreseen but cannot be forced'). The apparent contradiction resolves when you note the different contexts: in Chapter 4, you cannot force the enemy to be conquerable; in Chapter 6, you can manufacture your own conditions for victory through concentration and deception.

可使無鬥 — 'can be rendered unable to fight.' Not that the enemy chooses not to fight, but that his forces are so dispersed, so dislocated, that he cannot bring them to bear. He has men but cannot use them.

策 (ce) — to probe, to assess, to calculate. 作 (zuo) — to stir up, to provoke into action. 形 (xing) — to shape a situation, to make the enemy reveal himself. 角 (jue/jiao) — to cross horns, to skirmish, to test in a limited engagement. These four verbs describe an escalating sequence of intelligence-gathering: analysis, provocation, deception, and combat reconnaissance.

深間 (shen jian) — 'deep spies' or 'deeply planted agents.' 間 is the word for spy/agent used extensively in Chapter 13. Even the best-placed spies cannot discover a disposition that does not exist.

人皆知我所以勝之形而莫知吾所以制勝之形 — a crucial distinction. 勝之形 is the visible shape of the victory — the troop movements, the battle formation that won. 制勝之形 is the underlying strategic logic that created the conditions for that formation to succeed. The public sees the battle; no one sees the campaign of deception, concentration, and timing that made the battle a foregone conclusion.

戰勝不復 — 'victories are never repeated.' Each engagement is unique because the configuration of xu and shi — emptiness and fullness — is always different. A commander who tries to repeat a previous winning formula will fail because the enemy adapts.

兵形象水 — 'the form of war is like water.' This is Sunzi's most famous metaphor and the summary of the entire chapter. Water is the perfect model for xu-shi warfare: it flows to the empty spaces, it fills the low ground, it follows the path of least resistance, and it does so without fixed shape.

避實而擊虛 — 'avoid the full and strike the empty.' This six-character phrase distills the chapter's argument. 實 (shi, 'full') is where the enemy is concentrated and strong; 虛 (xu, 'empty') is where he is dispersed and weak. This formulation became a foundational maxim in Chinese strategic thought.

五行 (wuxing) — the Five Phases: wood, fire, earth, metal, water. Each phase overcomes and is overcome by another in a cycle (wood overcomes earth, earth overcomes water, etc.), but none permanently dominates — hence 'no constant dominance' (無常勝). Sunzi invokes this cosmological principle to reinforce his argument: nothing in war is fixed.

謂之神 (wei zhi shen) — 'this is called divine.' 神 is the highest praise in the classical Chinese vocabulary for military skill, meaning something beyond human understanding — uncanny, spirit-like, transcending ordinary calculation. The chapter ends where it began, with the idea that mastery of xu-shi produces results so extraordinary they appear supernatural.

The chapter closes with a cosmological coda: the Five Phases, the four seasons, the length of days, the phases of the moon — nothing in nature stays fixed. Sunzi's final argument is that war, like nature, is an endless process of change. The commander who grasps this and adapts fluidly will never be defeated.