It is clear that this question most easily arises if we are preoccupied with cases in which there are things flowing by us, – – as logs of wood float down a river. In such a case we can say the logs which have passed us are all down towards the left and the logs which will pass us are all up towards the right. We then use this situation as a simile for all happening in time and even embody the simile in our language, as when we say that “the present event passes by” (a log passes by), “the future event is to come” (a log is to come). We talk about the flow of events; but also about the flow of time – – the river on which the logs travel.