“The middle of the 19th century; nearly 150 years ago. Forget what you know. Forget the stale and unjustifiable notion that 19th-century art was tame and gentle, that the impressionists were ‘chocolate-box artists’, that modernism began in 1900. The truth is that everything great about modern art – and, perhaps more significantly, everything about it that still lives – was invented in the undervalued 19th century.”