Sun Tzu, The Art of War

"But a kingdom that has once been destroyed can never come again into being; nor can the dead ever be brought back to life."

"Appear weak when you are strong, and strong when you are weak."

"You can be sure of succeeding in your attacks if you only attack places which are undefended.You can ensure the safety of your defense if you only hold positions that cannot be attacked."

"Supreme excellence consists of breaking the enemy's resistance without fighting."

"Foreknowledge cannot be gotten from ghosts and spirits, cannot be had by analogy, cannot be found out by calculation. It must be obtained from people, people who know the conditions of the enemy."