6.10

"Therefore, if he prepares his front, his rear will be few. If he prepares his rear, his front will be few. Thus, if he prepares his right, his left will be few. If he prepares his left, his right will be few. And if he doesn't have a place where he is not prepared, then there will be no place that will not be few."
- Sun Tzu

Here Sun Tzu is expounding on his logic in the previous verse, where he says, "If the places where the enemy must prepare is many, then the places where we join in battle will be few."

Sun Tzu's point in this passage is not simply that in preparing on one side, one becomes weak in another side. Rather, his point is that in having a clear position while one is formless makes it so that one has clear openings to attack while the enemy has only bad options. The enemy must constantly shift his defenses since he doesn't know where his opponent is going to attack. This shifting or anxiety - from not being able to see his opponent's positioning and from not having the control over the ground - is what allows for his opponent to take advantage and attack.

This is why, for Sun Tzu, it is critical that one occupy the ground of battle first and take up a formless position. This is what allows one to take control over the dynamic of the battle, to put the enemy on the defensive, and to, thus, thin out his defenses so that one can find the vulnerable points in his defense.

In life, the same principle obviously applies. What you are after is control over the dynamic of the competition. You want to get into a position where your competition is reacting to you without any ability to predict what you'll do next. This involves being prepared, taking the initiative, putting the competition on the defensive, and advancing at an angle that is unexpected yet powerful.

This takes a lot of calculation, but this is why you must always take a concealed position and never pitch a battle on ground that is already occupied. Always strive first to find niche where you can dominate.