It is a subliminal thing. It is the tick of a clock that has ticked so long one no longer notices. Something is in a room when a man lives in it. Something is not in the room when a man is dead in it

It is a subliminal thing. It is the tick of a clock that has ticked so long one no longer notices. Something is in a room when a man lives in it. Something is not in the room when a man is dead in it. (Ray Bradbury, A Pleasure to Burn: Fahrenheit 451 Stories)