The exhibition at the National Galleries of Scotland in Edinburgh (at the Mound) commemorating the 20th anniversary of Warhol's death has dramatically set to rights the prevalent theory of the 1990s that by the time he died Warhol's best work was long back in time, that he was by then a spent force. Now more tellingly the art market has shown dramatic rises in the saleroom value of Warhol works, into the stratosphere brackets usually occupied by such key artists in history as Picasso and Duchamp. The curators of the Edinburgh Festival show had taken a precautionary line by pursuing not a chronological sequence of his work, but a thematic approach, dealing with such groupings as 'Consumer Products'. 'War, Death and Religion' and 'Death and Disaster'. Warhol had focussed critically in America on 'the Rise of the Religious Right', tellingly for today, and the assassination of President Kennedy and the tragedy of his widow Jacqueline. As well as the images of Mao, such themes do mark out critical turning points in recent American history, and plot social impact and change in a manner not usually recognised at the time. Warhol has become America's equivalent megastar to Picasso and Duchamp. The exhibition will be reviewed here in September.