Once while fishing (and not catching many fish) I tried to decide how a flowing stream best represented the flow of time. I decided it depended on the point of view. To me, wading in the creek, the future was upstream, where water molecules were on their way to flow past me eventually. To a boat coming downstream (or a water molecule), the future was further downstream and the past was upstream. I highly recommend this sort of musing on days when the fish aren't biting.