Thoroughbred portrait: George Stubbs's Whistlejacket

The solitary splendour of this rearing racehorse is transfigured into something philosophical and metaphysical by the blank olive space in which Stubbs sets the magnificent creature. Shadows of Whistlejacket’s fetlocks reveal this is not an unfinished work but was planned in this radical way. The horse’s eye stares back at the beholder, passionate, enigmatic, fathomless. This is a great work of the Enlightenment, when attitudes to nature were changing rapidly. Stubbs reveals the mystery of a living being, in a painting that gives a horse the dignity of one of Rembrandt’s portrait subjects
Illustration: Photograph: The National Gallery, London