Know the enemy, know yourself; your victory will never be endangered. Know the ground, know the weather; your victory will then be total.

The end and aim of spying in all its five varieties is knowledge of the enemy; and this knowledge can only be derived, in the first instance, from the converted spy. Hence it is essential that the converted spy be treated with the utmost liberality.

The good fighters of old first put themselves beyond the possibility of defeat, and then waited for an opportunity of defeating the enemy.

Regard your soldiers as your children, and they will follow you into the deepest valleys; look upon them as your own beloved sons, and they will stand by you even unto death.

When you do battle, even if you are winning, if you continue for a long time it will dull your forces and blunt you edge...If you keep your armies out in the field for a long time, your supplies will be insufficient. Transportation of provisions itself consumes 20 times the amount transported.

To persuade your enemy to (retreat) before the fight is to defeat them even before the battle begins. An enemy made ally is no longer an enemy.

Hence the saying: The enlightened ruler lays his plans well ahead; the good general cultivates his resources.