IN the middle of the open space of Parker’s Piece in Cambridge is a solitary lamp post known as ‘Reality Checkpoint’.

The origins of its name are obscure. Does it mark the boundary between Town and Gown: between the Ivory Tower and the real world?

Or does its name arise from the risk of colliding with it if your mind is on other things?

Standing at the intersection of two major paths, the lamp post confronts anyone lost in thought or conversation with reality in the form of a nasty bump.

But my preferred theory is that the Parker’s Piece light is one of those special places that spring us into a proper awareness of who and where we are.

Much of the time we go through life on auto-pilot, forgetting to feel the ground beneath our feet, the air in our lungs, the uniqueness of the present moment where past and future meet.

We all need reality checkpoints. For many people, churches play this role.

The atheist poet Philip Larkin felt this strongly.

In his poem Church Going he describes the compulsion he often felt to enter an empty church:

Once I am sure there’s nothing going on / I step inside, letting the door thud shut.

And, once in, he contemplates the power the building has to gather and sift all that is left inarticulate in our everyday routines:

A serious house on serious earth it is, In whose blent air all our compulsions meet, Are recognised, and robed as destinies.

Churches have this power; so, too, do certain natural places, often ones that we have known and loved for a long time.

For me, two such places are Wittenham Clumps next to the Thames at Days Lock and White Horse Hill above Uffington.

I have known them both from childhood and with each return visit they worm themselves further into my sense of being. I first went to the Clumps on my father’s back and have returned on countless occasions: in sun and rain, through snow and floodwater; happily with my wife and children; alone, grieving for my dying mother.

Even on the map these places where the contour lines cluster command our attention; and in the flesh they speak all the more powerfully.

At Uffington the intertwining of a startling landscape with layers of human habitation over at least three millennia is remarkable.

Uffington Hill’s northern escarpment plunges 300 feet in less than a quarter of mile: it is exposed and dramatic.

But with its twists and folds, mirrored in the ditches and ramparts of the hill fort and the curves of the White Horse, it is also an intimate place of shelter and warmth.

Each of us has a different set of reality checkpoints, but we all need them.

They anchor us in the firm reality of the here and now, which is the one place where we will meet the God of all places and all times.

The place where we may turn aside, as Moses did at the Burning Bush, taking off his sandals and knowing the ground under his feet to be holy.