Law 48
By taking a shape, by having a visible plan, you open yourself to attack. Instead of taking a form for your enemy to grasp, keep yourself adaptable and on the move. Accept the fact that nothing is certain and no law is fixed. The best way to protect yourself is to be as fluid and formless as water; never bet on stability or lasting order. Everything changes. –Robert Greene, The 48 Laws of Power (review)
Sun Tzu says the same thing in Chapter 6 of The Art of War:
Provoke him, to know his patterns of movement. Determine his position, to know the ground of death and of life. Probe him, to know where he is strong and where he is weak. The ultimate skill is to take up a position where you are formless.
If you are formless, the most penetrating spies will not be able to discern you, or the wisest counsels will not be able to do calculations against you. With formation, the army achieves victories yet they do not understand how. Everyone knows the formation by which you achieved victory, yet no one knows the formations by which you were able to create victory. Therefore, your strategy for victories in battle is not repetitious, and your formations in response to the enemy are endless.
The army’s formation is like water. The water’s formation avoids the high and rushes to the low. So an army’s formation avoids the strong and rushes to the weak. Water’s formation adapts to the ground when flowing. So then an army’s formation adapts to the enemy to achieve victory. Therefore, an army does not have constant force, or have constant formation.
Those who are able to adapt and change in accord with the enemy and achieve victory are called divine.