And this scene from Heathrow Airport just before Christmas shows even more clearly how the time of day, the day of the week, the time of the year, the time the flight leaves, or arrives - how all these things rule our lives. We can measure time, we can set our watches, we run national rail services, we organise flights to and from international airports, we can compute time from billions of years ago, right down to the nearest nano-second - perhaps this picture sums up our current world and its preoccupations very neatly - but in case we might think this is a modern 21st century preoccupation ...