"If you know the enemy and know yourself, you need not fear the results of a hundred battles.". [-Chinese general Sun Tzu, The Art of War,(NewTork: Doubleday,1988)]

Knowing yourself is so important. When you know how you will act in different situations you can then plan accordingly. If you know how your enemy is going to attack you then you can brace yourself. If you know both yourself and your enemy then it is hard to loose.