You cannot know if you will be successful or not. You can only prepare for battle and it must be done with all of your heart and with all of your consciousness. In that manner, you will have an edge.

In all fighting, the direct method may be used for joining battle, but indirect methods will be needed in order to secure victory. Indirect tactics, efficiently applied, are inexhaustible as Heaven and Earth, unending as the flow of rivers and streams; like the sun and moon, they end but to begin anew; like the four seasons, they pass away to return once more.

Knowledge of the enemy's dispositions can only be obtained from other men.

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.

The skillful tactician may be likened to the shuai-jan. Now the shuai-jan is a snake that is found in the Ch'ang mountains. Strike at its head, and you will be attacked by its tail; strike at its tail, and you will be attacked by its head; strike at its middle, and you will be attacked by head and tail both.

Carefully compare the opposing army with your own, so that you may know where strength is superabundant and where it is deficient.

If the enemy opens the door, you must race in.