Sun Tzu on the Art of Warby Sun Tzu
Tactical Dispositions 
Sun Tzu said: The good fighters of old first put themselves beyond the possibility of defeat, and then waited for an opportunity of defeating the enemy.
To secure ourselves against defeat lies in our own hands, but the opportunity of defeating the enemy is provided by the enemy himself. 
Thus the good fighter is able to secure himself against defeat,  but cannot make certain of defeating the enemy.
Hence the saying: One may KNOW how to conquer without being able to DO it.
Security against defeat implies defensive tactics; ability to defeat the enemy means taking the offensive. 
Standing on the defensive indicates insufficient strength; attacking, a superabundance of strength.
The general who is skilled in defense hides in the most secret recesses of the earth;  he who is skilled in attack flashes forth from the topmost heights of heaven.  Thus on the one hand we have ability to protect ourselves; on the other, a victory that is complete.
To see victory only when it is within the ken of the common herd is not the acme of excellence. 
Neither is it the acme of excellence if you fight and conquer and the whole Empire says, "Well done!" 
What the ancients called a clever fighter is one who not only wins, but excels in winning with ease. 
Hence his victories bring him neither reputation for wisdom nor credit for courage. 
He wins his battles by making no mistakes.  Making no mistakes is what establishes the certainty of victory, for it means conquering an enemy that is already defeated.
Hence the skillful fighter puts himself into a position which makes defeat impossible, and does not miss the moment for defeating the enemy. 
Thus it is that in war the victorious strategist only seeks battle after the victory has been won, whereas he who is destined to defeat first fights and afterwards looks for victory. 
The consummate leader cultivates the moral law, and strictly adheres to method and discipline; thus it is in his power to control success.
In respect of military method, we have, firstly, Measurement; secondly, Estimation of quantity; thirdly, Calculation; fourthly, Balancing of chances; fifthly, Victory.
Measurement owes its existence to Earth; Estimation of quantity to Measurement; Calculation to Estimation of quantity; Balancing of chances to Calculation; and Victory to Balancing of chances. 
A victorious army opposed to a routed one, is as a pound's weight placed in the scale against a single grain. 
The onrush of a conquering force is like the bursting of pent-up waters into a chasm a thousand fathoms deep.
|||Ts`ao Kung explains the Chinese meaning of the words for the title of this chapter: "marching and countermarching on the part of the two armies with a view to discovering each other's condition." Tu Mu says: "It is through the dispositions of an army that its condition may be discovered. Conceal your dispositions, and your condition will remain secret, which leads to victory,; show your dispositions, and your condition will become patent, which leads to defeat." Wang Hsi remarks that the good general can "secure success by modifying his tactics to meet those of the enemy."|
That is, of course, by a mistake on the enemy's part.
Chang Yu says this is done, "By concealing the disposition of his troops, covering up his tracks, and taking unremitting precautions."
I retain the sense found in a similar passage in ss. 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.
Literally, "hides under the ninth earth," which is a metaphor indicating the utmost secrecy and concealment, so that the enemy may not know his whereabouts."
Another metaphor, implying that he falls on his adversary like a thunderbolt, against which there is no time to prepare. This is the opinion of most of the commentators.
As Ts`ao Kung remarks, "the thing is to see the plant before it has germinated," to foresee the event before the action has begun. Li Ch`uan alludes to the story of Han Hsin who, when about to attack the vastly superior army of Chao, which was strongly entrenched in the city of Ch`eng-an, said to his officers: "Gentlemen, we are going to annihilate the enemy, and shall meet again at dinner." The officers hardly took his words seriously, and gave a very dubious assent. But Han Hsin had already worked out in his mind the details of a clever stratagem, whereby, as he foresaw, he was able to capture the city and inflict a crushing defeat on his adversary."
True excellence being, as Tu Mu says: "To plan secretly, to move surreptitiously, to foil the enemy's intentions and balk his schemes, so that at last the day may be won without shedding a drop of blood." Sun Tzu reserves his approbation for things that "the world's coarse thumb And finger fail to plumb."
"Autumn" hair" is explained as the fur of a hare, which is finest in autumn, when it begins to grow afresh. The phrase is a very common one in Chinese writers.
Ho Shih gives as real instances of strength, sharp sight and quick hearing: Wu Huo, who could lift a tripod weighing 250 stone; Li Chu, who at a distance of a hundred paces could see objects no bigger than a mustard seed; and Shih K`uang, a blind musician who could hear the footsteps of a mosquito.
The last half is literally "one who, conquering, excels in easy conquering." Mei Yao-ch`en says: "He who only sees the obvious, wins his battles with difficulty; he who looks below the surface of things, wins with ease."
Tu Mu explains this very well: "Inasmuch as his victories are gained over circumstances that have not come to light, the world as large knows nothing of them, and he wins no reputation for wisdom; inasmuch as the hostile state submits before there has been any bloodshed, he receives no credit for courage."
Ch`en Hao says: "He plans no superfluous marches, he devises no futile attacks." The connection of ideas is thus explained by Chang Yu: "One who seeks to conquer by sheer strength, clever though he may be at winning pitched battles, is also liable on occasion to be vanquished; whereas he who can look into the future and discern conditions that are not yet manifest, will never make a blunder and therefore invariably win."
A "counsel of perfection" as Tu Mu truly observes. "Position" need not be confined to the actual ground occupied by the troops. It includes all the arrangements and preparations which a wise general will make to increase the safety of his army.
Ho Shih thus expounds the paradox: "In warfare, first lay plans which will ensure victory, and then lead your army to battle; if you will not begin with stratagem but rely on brute strength alone, victory will no longer be assured."
It is not easy to distinguish the four terms very clearly in the Chinese. The first seems to be surveying and measurement of the ground, which enable us to form an estimate of the enemy's strength, and to make calculations based on the data thus obtained; we are thus led to a general weighing-up, or comparison of the enemy's chances with our own; if the latter turn the scale, then victory ensues. The chief difficulty lies in third term, which in the Chinese some commentators take as a calculation of NUMBERS, thereby making it nearly synonymous with the second term. Perhaps the second term should be thought of as a consideration of the enemy's general position or condition, while the third term is the estimate of his numerical strength. On the other hand, Tu Mu says: "The question of relative strength having been settled, we can bring the varied resources of cunning into play." Ho Shih seconds this interpretation, but weakens it. However, it points to the third term as being a calculation of numbers.
Literally, "a victorious army is like an I (20 oz.) weighed against a SHU (1/24 oz.); a routed army is a SHU weighed against an I." The point is simply the enormous advantage which a disciplined force, flushed with victory, has over one demoralized by defeat." Legge, in his note on Mencius, I. 2. ix. 2, makes the I to be 24 Chinese ounces, and corrects Chu Hsi's statement that it equaled 20 oz. only. But Li Ch`uan of the T`ang dynasty here gives the same figure as Chu Hsi.