Mind is elusive, you cannot hold it in your hand. You cannot force it into a test-tube. The only way to know it is to know it from within, from your witnessing self. The more you become aware, the more you can watch your mind - its subtle functioning. The functioning is tremendously complex and beautiful. Mind is the most complex phenomenon on the earth, the most subtle flowering of consciousness. If you want to really understand what the mind is, then you will have to detach yourself from your mind, and you will have to learn how to be just a witness. That's what meditation is all about.