The Art of War: I, 1. "Sun Tzŭ said: The art of war is of vital importance to the State."

The Art of War: III, 18. "Hence the saying: If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle."