The theme of The Spiral is multi-layered. On a personal level, I remember as a child in living in Manchester, making things in our garden with the bits and pieces I unearthed there – the mysterious bits of clay pipes, bones and rounded glass, some brightly coloured fragments of someone else’s discarded pottery, the occasional old cobblestone from when the garden was distantly part of a farm, and strange bits of orange brick, much older than our house. When you are small, you save these as treasures. I still have some of them.

The spiral is a beautiful mathematical form that occurs in nature, for example in pine cones, sunflower seed-heads, and also in the shells of snails. My garden is full of snails and we wage a constant war against each other that I know I can never win. Every week in damp weather, I deport a bucket of them to the woods across the road, but there are always more to replace them. They are really very beautiful objects, and I acknowledge that they have more right to be in this garden (their ancestors have probably lived on this site for thousands, if not millions, of years), than the transient flowers and plants I annually import and which disappear at the first sign of cold weather. The snails merely seal themselves up and wait for the spring. Their descendants will be here long after we have gone, quietly and gently and nocturnally, rasping through the vegetation.

Henri Matisse loved spirals, and towards the end of his life made delicate collages of snail shells with paper. Andy Goldsworthy makes them with leaves. The materials themselves are without value. It is the act of recognition, collecting and making that makes them special, like ‘un-earthed’ treasure.