Chapter 4. Disposition of the Army,军形 explains the importance of defending existing positions until you can advance them and how you must recognize opportunities, not try to create them.

Ensure Undefeated-ness - Sun Tzu

English: Sun Tzu said: In ancient times, those who were skilful in warfare ensured that they would not be defeated and then waited for opportunities to defeat the enemy. The ability to prevent defeat lies on oneself while the opportunities of victory depend on the enemy. Thus those who are adept at warfare can ensure that they will not be defeated by the enemy, but will not be able to ensure victory over the enemy. Thus one is able to predict victory but not necessary be able to achieve it.

Modern: 孙子说：从前善于打仗的人，先创造不会被敌人战胜的条件，来等待可以战胜敌人的机会。不被战胜的主动权在自己，可战胜敌人的条件是敌人创造的。所以善于打仗的人，能做到不被敌人轻易取胜，可是不能肯定敌人必会被打败。所以说，胜利可以预知，但不能强求。

Original: 孙子曰：昔之善战者，先为不可胜，以待敌可胜。不可胜在己，可胜在敌。故善战者，能为不可胜，不能使敌人之可胜。故曰：胜可知，而不可为。

When to Offend or Defend - Sun Tzu

English: If the enemy cannot be overcome, defend. If the enemy can be overcome, attack. If resources are not available and in shortage, defend yourself. And vice versa. Those who are able to defend, is able to use the surrounding to conceal his troops well. Those who are able to attack, is able to attack in ways that is out of ordinary. As such he is not only able to ensure greatest self security and protection, he would also be able to achieve complete victories.

Modern: 当不可能战胜敌人时，应该进行防御。当可以战胜敌人时，应该进攻。采取守势是因为资源不足，采取攻势是因为资源充足或有余。善于防守者，深深隐蔽自己兵力于各种地形之下；善于攻击者，高度发挥自己的力量，像从天而降，所以能保存自己又获得全胜。

Original: 不可胜者，守也；可胜者，攻也。守则不足，攻则有余。善守者，藏于九地之下，善攻者，动于九天之上，故能自保而全胜也。

What is a True Military Strategist Part (I) - Sun Tzu

English: To predict a victory that cannot surpass the common military knowledge, is not the hallmark of a great military strategist. To win a battle that is praised by many, is not the hallmark of great military strategist either. Predicting and achieving such victories, is like lifting a hair which does not indicate that one has great strength or being able to see the moon and the sun does not mean one has great eyesight. And also similar to being able to hear the roar of the thunder does not mean one has sharp hearing. Ancient sages’ definition of generals who is adept at war are those that excelled in securing victories by choosing enemies that are easiest to overcome. Thus, one who is adept at war, wins without being known for his wisdom, reputation, courage and merit.

Modern: 预见胜利，不超过一般人的见识，不算高明中的高明，经过激烈战斗而后取胜，天下人都说好，也不算高明中的高明。这就像是举得起秋毫算不得力大，能看得见日 月算不得眼明，听得见雷声算不得耳灵。古时候善于打仗之人，选择能容易获胜的敌人，所以所得的胜利，既没智慧的名声，也没勇武的战功。

Original: 见胜不过众人之所知，非善之善者也；战胜而天下曰善，非善之善者也。故举秋毫不为多力，见日月不为明目，闻雷霆不为聪耳。古之所谓善战者，胜于易胜者也。故善战者之胜也，无智名，无勇功。

What is a True Military Strategist Part (II) - Sun Tzu

English: He wins battle with confidence and without making mistakes. He does not make mistakes because he adopts measures that lead to victories. Victory is already secured because the enemy is already in a position of defeat. Therefore, the person adept at warfare, will put himself in a position where odds of defeat is the smallest and grabs every opportunity to defeat the enemy. As such a would-be victorious army ensures victory before engaging the enemy. A would-be defeated troops will engage his enemy first before looking for chances of victory. The person adept in warfare not only cultivates his moral code but maintains law and order. In this way, he is able to govern and determine victory and defeat in war.

Modern: 所以他们取得胜利不会有差错。之所以没有差错是因为他们的作战措施是建立在必胜的基础上，战胜已处于失败地位的敌人。善于打仗的人，先立于不败之地，而又 不放过任何能胜敌人的机会。打胜仗的军队，先创造取胜的条件，而后同敌人作战。打败战的军队先同敌人交战，而后希望侥幸取胜。善于作战的人，修明政治，确 保法制，所以能够掌握胜败的决定权。

Original: 故其战胜不忒，不忒者，其所措必胜，胜已败者也。故善战者，立于不败之地，而不失敌之败也。是故胜兵先胜而后求战，败兵而先战而后求胜。善用兵者，修道而保法，故能为胜败之政。

Evaluating Operations - Sun Tzu

English: Now in warfare, evaluations must be made as follows: First, estimate the degree of difficulty; second, assess the scope of operation; third, calculation of own forces; fourth, comparison of forces; and fifth, establish the chances of victory. Based on the characteristics of the terrain, the degree of difficulty is estimated. Based on the degree of difficulty, the scope of operation is assessed. Based on the scope of operation, the calculation of own forces is made. Based on the calculation of own forces, comparisons are evaluated against those of the enemy. Based on the evaluations, the chances of victory can then be established.

Modern: 军事上，有五个范畴，一是“度”，二是“量”，三是“数”，四是“称”，五是“胜”。根据地形，可看出战役的难度，而从难度可看出战役所需要资源量，而从资源数量可看出所需的兵士数量，又从兵士数量作比较，判断谁强谁弱，就可知谁胜谁负。

Original: 兵法：一曰度，二曰量，三曰数，四曰称，五曰胜；地生度，度生量，量生数，数生称，称生胜。

Disposition of Army - Sun Tzu

English: Thus, a victorious army is like a heavy-weight matched against a feather-weight. A defeated army is like a feather-weigh matched against a heavy-weight. The person adept in warfare is able to command and direct his troops to fight like accumulated gush of water streaming down mercilessly from thousands of feet high. Such is the disposition of a powerful and victorious army.

Modern: 所以，胜利的军队与失败的军队相比，就像用“镒”称“铢”那样占有绝对优势；失败的军队较之以胜利的军队，就像用“铢”称“镒”那样处于绝对劣势。军事实力强大的胜利者指挥军队作战，就像决开在八千尺高处的溪中积水那样，一种力量的表现。

Original: 故胜兵若以镒称铢，故败兵若以铢称镒。称胜者之战民也，若决积水于千仞之溪者，形也。

Sumber : http://www.chinese-wiki.com/Sun_Tzu_Art_of_War_Chapter_4