Of all those in the army close to the commander none is more intimate than the secret agent; of all rewards none more liberal than those given to secret agents; of all matters none is more confidential than those relating to secret operations.

Be extremely subtle, even to the point of formlessness. Be extremely mysterious, even to the point of soundlessness. Thereby you can be the director of the opponent's fate.

Sweat more during peace: bleed less during war

If you fight with all your might, there is a chance of life; where as death is certain if you cling to your corner

What the ancients called a clever fighter is one who not only wins, but excels in winning with ease.

From a position of this sort, if the enemy is unprepared, you may sally forth and defeat him. But if the enemy is prepared for your coming, and you fail to defeat him, then, return being impossible, disaster will ensue.

Spies are a most important element in water, because on them depends an army's ability to move.