This chapter felt more allusive than the earlier ones. It kind of reminds me of sword manuals where the writer assumes the reader already has had F2F training and is "pointing" instead of "explaining".
I looked up "the nine heavens" and it didn't help much. Maybe the phrase changed meaning over time? It seems to have been connected to the planets after Ptolemy's model reached China, but I don't know if Sunzi wrote before or after that. If after, I wondered if maybe were some sort of planets/pantheon/astrology linkages, that would mean something to someone who caught more references than I do?
I see that The Art Of War has 13 chapters. If you had done them all, I'd have probably binged the whole sequence this evening :-)
This is a translation of Chapter 4 of The Art of War by Sunzi. No English sources were used.
孙子曰：昔之善战者，先为不可胜，以待敌之可胜。
Do not first seek victory. Establish conditions such that you cannot lose.
不可胜在己，可胜在敌。
Then await an opportunity to win.
故善战者，能为不可胜，不使敌之必可胜。
You can, with skill, survive, but only the enemy can permit your victory.
故曰：胜可知，而不可为。
Victory can be foreseen, but cannot be forced.
不可胜者，守也；可胜者，攻也。
If you cannot win, defend. If you can win, attack.
守则不足，攻则有余。
Defend when your forces are insufficient. Attack when your forces are ample.
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。
The capable defender hides under the nine earths. The capable attacker strikes from the nine heavens. Protect yourself and obtain total victory.
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。
Forseeing victory when the masses cannot is an imperfect perfection. Obtaining victory by moving everything under heaven is an imperfect perfection.
故举秋毫不为多力，见日月不为明目，闻雷霆不为聪耳。
It is like like lifting up the vellus hair of autumn's newborn fauna. Noticing the sun and moon does not indicate a keen eye. Hearing thunder does not indicate a keen ear.
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。
The great generals of history defeated weak enemies. They employed neither cleverness nor courage.
故其战胜不忒，不忒者，其所措必胜，胜已败者也。
They did not win by a hair. Victory was assured.
故善战者，立于不败之地，而不失敌之败也。
Firmly established, all they did was not lose.
是故胜兵先胜而后求战，败兵先战而后求胜。
Victorious armies first seek victory and then fight. Defeated armies first fight and then seek to win.
善用兵者，修道而保法，故能为胜败之政。
Good commanders maintain proper military governance in order to govern the outcome of war.
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。
You must pay attention to:
The territory determines the quantities. The quantities determines the numbers. The numbers determine the names. The names determine victory.
故胜兵若以镒称铢，败兵若以铢称镒。
The victorious soldier weighs a kilo and is called a gram; the defeated soldier weighs a gram and is called a kilo.
胜者之战民也，若决积水于千仞之溪者，形也。
The good general embodies the form an unstoppable river with a thousand tributaries.