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.
That is, of course, by a mistake on the enemy's part.
Thus the good fighter is able to secure himself against defeat,
Chang Yu says this is done, "By concealing the disposition of his troops, covering up his tracks, and taking unremitting precautions."
but cannot make certain of defeating the enemy.
Hence the saying: One may KNOW how to conquer without being able to DO it.
DO IT Q