At first sight Ai Weiwei’s installation “Sunflower Seeds” presents us with an undifferentiated field of grey, filling the space between the bridge and the end wall of Tate Modern’s Turbine Hall. It is almost disappointing…

But you can trudge over all 100 million of them, walk or skip or dance on these seeds, all of them Made in China. Or scoop up handfuls and let them run through your fingers, in the knowledge that someone, an old lady or a small-town teenager in Jingdezhen, has delicately picked up each one and anointed it with a small brush. Every seed is painted by hand. The town that once made porcelain for the imperial court has been saved from bankruptcy by making sunflower seeds. It is absurd.

Ai Weiwei is surely one of the great artists of our day.