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

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.

There are only five notes in the musical scale, but their variations are so many that they cannot all be heard. There are only five basic colors, but their variations are so many that they cannot all be seen. There are only five basic flavors, but their variations are so many that they cannot all be tasted. There are only two kinds of charge in battle, the unorthodox surprise attack and the orthodox direct attack, but variations of the unorthodox and the orthodox are endless. The unorthodox and the orthodox give rise to each other, like a beginningless circle-who could exhaust them?

To conquer the enemy without resorting to war is the most desirable. The highest form of generalship is to conquer the enemy by strategy.

If not in the interests of the state, do not act. If you cannot succeed, do not use troops. If you are not in danger, do not fight.

It is ten thousand times cheaper to pay the best spies lavishly than even a tiny army poorly.

In conflict, straightforward actions generally lead to engagement, surprising actions generally lead to victory.