5 ideas
All warfare is based on creating false appearances: appear weak when strong, near when far, disorderly when organized. By controlling what the opponent believes about your position and intentions, you induce them to commit errors and move where you want them.
Outcomes are predictable in advance by assessing five factors — moral influence, weather, terrain, command, and method — for both sides and comparing them. If you know yourself and the enemy you cannot lose; knowing only one of the two means you win some and lose some; knowing neither guarantees defeat.
Every engagement uses the zheng, the direct and expected force that fixes the enemy in place, together with the qi, the indirect and surprising force that decides the outcome. The two constantly turn into each other: once a surprise is expected it becomes orthodox, and an orthodox move can itself become the surprise. The combinations are therefore inexhaustible, just as five notes produce endless melodies.
The best strategy attacks the enemy's plans, the next best breaks their alliances, the next attacks their army in the field, and the worst besieges walled cities. Each step down the ladder costs more resources and destroys more of what you hoped to gain. The ideal is to take the opponent whole and intact, so subduing them without fighting is the highest skill.
The victorious general wins in the temple calculations before the war, by comparing both sides across the five factors: moral law, heaven, earth, the commander, and method and discipline. The losing army fights first and hopes to win, while the winning army first secures victory and only then seeks battle.