Andy Goldsworthy: Cairn at Penpont, Scotland

It's hard to explain how what is basically an egg-shaped heap of sandstone, sitting on top of a green pasture used by cows for grazing, on the outskirts of a tiny village in rural Scotland, can be so powerful. But that's the beauty of Andy Goldsworthy's sculptures: they're deceptively simple.

Penpont is about 14 miles north of Dumfries, in southwestern Scotland. The cairn sits on a hill on the Thornhill side. To get there, head up the A76 from Dumfries, and turn left once you're through the town of Thornhill, where the signpost says Penpont.

I believe sculpture can teach a painter a lot; about form and shape, about using materials, about shadow and light. Even more so a landscape artist, who sources art materials from the environment, who creates with nature. It's far too easy for a painter to be removed from their materials, to not know what makes up the paint they're using.