Hence the saying: One may know how to conquer without being able to do it.
The nature of war is constant change.
Every battle is won before it is fought.
War is a matter of vital importance to the state; the province of life or death; the road to survival or ruin. It is mandatory that it be thoroughly studied.
Defeat the enemies strategy.
Like the sun and moon, they end but to begin anew; like the four seasons, they pass away to return once more.