The art of war teaches us to rely not on the likelihood of the enemy's not coming, but on our own readiness to receive him; not on the chance of his not attacking, but rather on the fact that we have made our position unassailable.
So a military force has no constant formation, water has no constant shape: the ability to gain victory by changing and adapting according to the opponent is called genius.
There is nothing more difficult than tactical maneuvering. The difficult consists in turning the devious into the direct, and misfortune into gain. Thus, to take a long and circuitous route after enticing the enemy out of the way, and though starting after him to contrive to reach the goal before him, shows knowledge of the artifice of deviation.
The clever combatant looks to the effect of combined energy, and does not require too much from individuals. Hence his ability to pick out the right men and utilize combined energy