The view from my office window in spring
"Time is an illusion - lunchtime doubly so."
The immortal wisdom of the great Ford Prefect (in The Hitch-Hiker's Guide to the Galaxy) describes well the view many people have of time. It's all circular - what goes around, comes around - if the Tories are in power now, Labour will be soon. It's undoubtedly true in many ways. Things do happen much the same in cycles of time. My office window looks like this every year, and its pattern is regular and fairly predictable.
How we measure time is in many ways socially constructed. An excellent recent episode of In Our Time (sic) on Radio 4 told us that the Babylonians divided the hour into 60 minutes purely for mathematical convenience (they liked 60 because lots of other numbers divide into it). Likewise, when the face of mechanical clocks were invented, they paralleled sunrises, and the movement of the hand followed the same direction as the movement of the sun - so that 'clockwise' would be the other way round if the mechanical clock had been invented in the southern hemisphere.
But it's Holy Week, and that has a quite different conception of time. We rush towards Calvary and then we move on to Easter. There's no circularity here. The events happened once only, for all time. We commemorate them each year, but they don't come back again. We talk about "the first Christmas", but never "the first Easter". There was only one Easter, the extraordinary time when a wholly good man suffered and died terribly, and then was transformed completely after death by God. That was a one-time event. Ford Prefect was wrong: not all time is an illusion.