Why wilt thou be so sottish, such an enemy to thyself, as to prefer puddle-water, and that poisoned too and stolen, before pure living waters out of thy own well?
So the principles of warfare are: Do not depend on the enemy not coming, but depend on our readiness against him. Do not depend on the enemy not attacking, but depend on our position that cannot be attacked.
Never abandon the possibility of attack. Attack even from a position of inferiority, to disrupt the enemy's plans. This often results in improving one's own position.
A king may be a tool, a thing of straw; but if he serves to frighten our enemies, and secure our property, it is well enough; a scarecrow is a thing of straw, but it protects the corn.
Our faith in others betrays that we would rather have faith in ourselves. Our longing for a friend is our betrayer. And often with our love we want merely to overcome envy. And often we attack and make ourselves enemies, to conceal that we are vulnerable.
Though fraud in all other actions be odious, yet in matters of war it is laudable and glorious, and he who overcomes his enemies by stratagem is as much to be praised as he who overcomes them by force.