My understanding is that mushin is a level of awareness and detachment. You're not thinking, not expecting, not caring -- but completely aware and acting completely under control at the same time. Something happens, and you respond correctly, smoothly, intentionally -- but you haven't planned it and you don't do it in a consciously planned manner.
Confused yet? It's a really hard concept to understand -- but unmistakable when you see and experience it.
Confused yet? It's a really hard concept to understand -- but unmistakable when you see and experience it.