What it comes down to mostly, is that one moment when suddenly you become hyperaware of your being, and your being there. It's the forgotten sound of the ventilation, the groans of the refrigerator motor kicking on, the way everything slows to an infernal drip of an otherwise distant memory. It's an irrational fear of late night vacuums and early morning silence.  The stillness of that feeling reminds you why you came in the first place and of what you left behind. You can try but you can't touch it. It eludes the most envious and skilled of us and flaunts the recessed look in your eyes.