There is no great harm in the theorist who makes up a new theory to fit a new event. But the theorist who starts with a false theory and then sees everything as making it come true is the most dangerous enemy of human reason.
It is one of the great troubles of life that we cannot have any unmixed emotions. There is always something in our enemy that we like, and something in our sweetheart that we dislike.
So the principles of warfare are: Do not depend on the enemy not coming, but depend on our readiness against him. Do not depend on the enemy not attacking, but depend on our position that cannot be attacked.