Mind is an empty, bounded space that we clutter with 'worthy' activities: thinking, anxiety, fantasy, visions, hopes, dreams, etc. We foolishly confuse these activities with mind itself, and then we get ourselves into the ridiculous position of being unable to turn them off when we need – when we want to relax or rest or meditate – that is, simply experience pure, unadulterated mind. And such experience is crucially important for those doing internal work. We must discover the boundary of our mind by clearing it of activity and allowing it to fill with energy otherwise we never really know what is internal and what is external – we never really grow up.