War, The Art of War (孫子)

兵者，詭道也。故能而示之不能，用而示之不用，近而示之遠，遠而示之近。

- 孫子

All warfare is based on deception. Hence, when we are able to attack, we must seem unable; when using our forces, we must appear inactive; when we are near, we must make the enemy believe we are far away; when far away, we must make him believe we are near.

- Sun Tzu, The Art of War

Common examples can also be found in English use, such as verse 18 in Chapter 1. This has been abbreviated to its most basic form and condensed into the English modern proverb:

All warfare is based on deception.

http://en.wikipedia.org/wiki/The_Art_of_War