It is essential for a general to be tranquil and obscure, upright and self-disciplined, and able to stupefy the eyes and ears of the officers, keeping them ignorant. He alters his management of affairs and changes his strategies to keep other people from recognizing them. He shifts his position and traverses indirect routes to keep other people from being able to anticipate him.
Sun Tzu, The Art of War, c. 450 BCE