Awareness & Movement

...You are asking what I think the most important lesson in the martial arts is?

Can I cheat a little and pick two important points?

The first lesson that I would stress is awareness of your surroundings. Nobody suddenly materialized in front of you with an attack, so if you find yourself in that situation you have to ask yourself what happened to awareness? Awareness extends beyond the personal to the situational in terms of exits, entrance points, and objects that surround you. Awareness is being aware of your own ego and knowing when to hold your ground and when to give way.

My second point? Movement. No matter what happens, what the other person is trying to do, what you are trying to do, is to keep moving. Just moving around give you a chance and is life, at the very least it makes you harder to hit.

Fred Feddeck, Shidoshi, Bujinkan Shinmyoken Dojo
http://shinmyoken-dojo.blogspot.com/2009/02/awareness-and-movement-in-martial-arts.html