Sun-tzu, The Art of War. Emptiness and Fullness
"Therefore good warriors cause others to come to them, and do not go to others. What causes opponents to come of their own accord is the prospect of gain. What discourages opponents from coming is the prospect of harm. So when opponents are at east, it is possible to tire them. When they are well fed, it is possible to starve them. When they are at rest,it is possible to move them. Appear where they cannot go, head for where they least expect you. To travel hundredsof miles without fatigue, go over land where there are no people. To unfailingly take what you attack, attack where there is no defense. For unfailingly secure defense, defend where there is no attack. So in the case of those who are skilled in attack, their opponents do not know where to defend. In the case of those skilled in defense, theiropponents do not know where to attack. Be extremely subtle, even to the point of formlessness. Be extremely mysterious, even to the point of soundlessness. Thereby you can be the director of the opponent’s fate. To advance irresistibly, push through their gaps. To retreat elusively, outspeed them. Therefore when you want to do battle, even if the opponent is deepl entrenched in a defensive position, he will be unable to avoid fighting if you attack where he will surely go to the rescue. When you do not want to do battle, even if you draw a line on the ground to hold, theopponent cannot fight with you because you set him off on the wrong track. Therefore when you induce others to construct a formation while you yourself are formless, then you are concentrated while the opponent is divided. When you are concentrated into one while the opponent is divided into ten, you are attack at a concentration of ten to one, so you outnumber the opponent. If you can strike few with many, you will thus minimize the number of those with whom you do battle. Your battleground is not to be known, for when it cannot be known, the enemy makes many guard outposts, and since multiple outposts are established, you only have to do battle with small squads. So when the front is prepared, the rear is lacking, and when the rear is prepared the front is lacking. Preparedness on the left means lacks on the right, preparedness on the right means lack on the left. Preparedness everywhere means lack everywhere. The few are those on the defensive against others, the many are those who cause others to be on the defensive against themselves. So if you know the place and time of battle, you can join the fight from a thousand miles away. If you do not know the place and time of battle, then your left flank cannot save your right, your right cannot save your left, your vanguard cannot save your rearguard, and your rearguard cannot save your vanguard, even in a short range of a few to a few dozen miles. According to my assessment, even if you have many more troops than others, how can that help you to victory? So it is said that victory can be made. Even if opponents are numerous, they can be made not to fight. So assess them to find out their plans, both the successful ones and the failures. Incite them to action in order to find out the patterns of movement and rest.Induce them to adopt specific formations, in order to know the ground of death and life. Test them to find out where they are sufficient and where they are lacking. Therefore the consummation of forming an army is to arrive at formlessness. When you have no form, undercover espionage cannot find out anything intelligence cannot form a strategy. Victory over multitudes by means of formation is unknowable to the multitudes. Everyone knows the form by which I am victorious, but no one knows the form by which I ensure victory. Therefore victory in war is not repetitious, but adapts its form endlessly. Military formation is like water — the form of water is to avoid the high and go to the low, the form of a military force is to avoid the full and attack the empty; the flow of water is determined by the earth, the victory of a military force is determined by the opponent. So a military force has no constant formation, water has no constant shape: the ability to gain victory by changing and adapting according to the opponent is called genius."
– SUN TZU –