How to put the nation’s pupils off great art for ever

‘Bathers at Asnières’ is a dreamily double-edged impressionist painting: an idyll as tricksy as the tiny dots, instead of brushstrokes, that Seurat used to paint. Young Parisian workers are stretched out like cats in the sun, or swimming in water so cool that you can almost feel it, and yet in the background the chimneys puff away, calling them back to work.