If you go through the list of things that are not possible you're left with a very finite amount of possibilities. The fancy name for this is constraint theory. It's a nonquantitative model, but it's a field of mathematics.

The warrior must continue to make decisions in the face of extreme circumstances. He cannot afford to get angry or frightened.

When you're young and going to war, it's a genuinely exciting moment. You are going to risk yourself. On the battlefield, you are suddenly free. You realize: I'm here, I'm in it. Exaltation. Suddenly you're hit by another extraordinary feeling: my God, I can be killed. And: will I embarrass myself? It's like you're in a kaleidoscope and all of these extraordinary feelings are zipping by.

War is an extraordinary condition to be in - to be, for example, in the combat information center of a warship [and behaving] as though you were merely processing credit card applications. [Instead,] the information you're processing is that an incoming missile is 15 kilometers away, now 10 kilometers away, now 5 kilometers. You have to separate yourself psychologically from the fact that your mortal existence may well end. That is the ancient reality of war.

Wars are times of intense technological transformation, because societies invest - sometimes with extensive borrowing - when and where matters of life and death are at stake.

If you lose yourself to rage in the complexity of battle, you are going to be lost.

If you go through the list of things that are not possible you're left with a very finite amount of possibilities. The fancy name for this is constraint theory. It's a nonquantitative model, but it's a field of mathematics.