Walking along the soft turf of the coastal path at Birsay on Orkney, my attention was caught by a little patch of pink thrift, waving around in the onshore breeze. It was growing right on the edge, where the ground drops away down a shallow cliff to the rocky foreshore. A few of the flowers on their tough little stems were open, reaching for the sun, pink petals shading into purple; others were still bundled up in tight buds, the overlapping petals making for an intense cerise.

Behind and below on the foreshore I could see lines of jagged rocks—sandstone, like most of Orkney, the strata tipped from the horizontal and broken across so the layers of sedimentation were clearly visible. In places the strata were cracked vertically as well, giving the appearance of building blocks ready to hand for Neolithic architects such as those who constructed the tomb at Maeshowe, and the great stone circles of Brodgar and Stenness. In the valleys between the ridges, boulders of assorted sizes and colours, rounded by the sea, had been tossed by the waves into rough heaps.

The sea was retreating with the falling tide. The waves gathered in the shallows, broke just offshore, rolled up the slope of the rocks and spilled over the broken edges. White foam poured down, inundating the quieter water in little inlets and rockpools, and then streamed back into the sea. Another wave crashed in, breaking slightly differently, the pattern of flood and retreat repeating, variations on the theme, again and again.

Higher up the foreshore, some rockpools were now completely separated from the sea, warming in the thin sunshine. Small children, barefoot, crowded around them, hauling up crabs and other living things in nets and dropping them in their bucket and rushing back to show Mum. Others searched carefully for the lucky cowry shells known locally Groatie Buckies.

I looked back at the thrift. It seemed so fragile here, growing in shallow soil, exposed to the wind and the sea and the salt spray. So, I thought, are the children, with their long limbs and thin bodies, full of life one moment, shivering with cold the next. And so too, in a larger context, is the land of Orkney, soft sandstone exposed to the pounding of the sea.

For a tiny moment I glimpsed how everything is forever changing, nothing is permanent, the world is not fixed form but endless dance. And then it solidified back into taken-for-granted things in themselves. I was hungry: it was time for lunch.