Echo, echo, echo, the words die away across the canyon, as the sound waves bounce repeatedly between the walls of rock before exhausting themselves into silence. Our perception is off something receding, moving away from us, into the past.
Simultaneously we consider time to be moving forward; we talk of in a half an hour¹s time as being a point in the future, full of the as yet un-happenned, whilst half an hour ago, is safely taken place and gone. But if an echo is the sound of something receding, of something behind, then should not the reverberations be occurring in the past, should they not in relation to our perception of time¹s trajectory have already happened? Instead the sound, the echo travels on, speeding forwards into the future, not behind but in front.