"All warfare is based on deception. Hence, when able to attack, we must seem unable, when using our forces we must seem inactive, when we are near, we must make the enemy believe that we are away; when far away, we must make him believe we are near. Hold out baits to entice the enemy. Feign disorder, and crush him.
If he is secure at all points, be prepared for him. If he is superior in strength, evade him. If your opponent is of choleric temper, seek to irritate him. Pretend to be weak, that he may grow arrogant.
If he is inactive, give him no rest. If his forces are united, separate them. Attack him where he is unprepared, appear where you are not expected. These military devices, leading to victory, must not be divulged beforehand." – Sun Tzu, The Art of War – Translation by Lionel Giles, 1910