The twilight of the gods has come to Tate Britain. Like a Wagnerian opera painted in mist and fire, the late works of JMW Turner rise from silence to throbbing power, wheel out their visionary leitmotifs, and crash in apocalyptic frenzy.
Wagner and Turner have a great deal in common. Both are artists of myth on a grand scale who wallow in magnificent ambiguities and lashings of atmosphere. In Turner's 1837 painting The Parting of Hero and Leander, a lover is drowned in a boiling roiling sea while heavenly fire glows red above a Greek city that hubristically totters on a mountaintop. How Wagnerian is that? It is all an allegory of doomed desire, a grandiose illumination of Turner's long, unreadable poem The Fallacies of Hope (again like Wagner, he wrote his own libretto).
In late 19th- and early 20th-century France the paintings of Turner hovered alongside Wagner's preludes in the imaginations of artists from Monet to Matisse, who learned from them how colour could be expressive, atmospheric, even abstract. Is Turner then the father of modern art? Do his woozy vortices of light usher in a new way of seeing the world – our way of seeing the world?
Art historians smile knowingly at that idea, pointing out that Turner is a man of the Romantic age whose art is dense with historical and mythological information, making it anachronistic to think he ever paints for painting's sake.
Late Turner – Painting Set Free drowns such quibbles under a flood of raw wild paint. We've seen all kinds of Turners portrayed by recent exhibitions of his works, from Turner the student of the Old Masters to Turner the nautical cove. Here at last is the Turner who matters – the man who invented modern painting.
The old cliche that Turner anticipated the Impressionists fades away in this exhibition. Not because it's untrue, but simply because it is so inadequate to his true influence. If you can see Monet's Impression: Sunrise foreshadowed in his watercolours you can also see how Salvador Dalí and Max Ernst echo Turner's more surreal moments – his trees that float in the sky like glowing jellyfish, his encrustations of edible-seeming paint – and how the American artist Cy Twombly reinterprets his classical scenes in paintings that are great lyrical sighs of abstraction and graffiti.
Turner's modernism flashes forth everywhere in this exciting, entrancing show. The curators' brilliant move is to mix up all the types of art he experimented with in his last years, from daring watercolours to unfinished canvases, without making prior judgments about which works represent the "real" Turner. One moment he is retuning to one of his earlier works – Regulus, first made in 1828 and reworked in 1837 – to intensify its blinding light; the next he is painting, in 1834-5, the Houses of Parliament on fire. For him this national disaster is a spectacle to be delighted in for its explosion of gold and bronze in the London night.
The critic John Ruskin, who championed Turner, later condemned the modernist Whistler for "throwing a pot of paint in the face of the public" in a near-abstract nocturne of fireworks over the Thames. Ruskin was kidding himself. It was his hero Turner who first used paint to create a sheer optical rush. When the Tower of London caught fire he captured that too as a pure visual thrill in a sequence of watercolours that are barely representational at all.
Turner's watercolours are his most radical works of all. Pale blues and searing pinks touch tiny worlds of feeling into existence.
To explain how a man who was born in 1775 and died in 1851 could anticipate so much of modern art I need to return to that comparison with Wagner (who was a lot younger). Both of these immense 19th-century creative figures take Romanticism to such an extreme that it breaks apart and becomes modernist. Critics who see Turner's enthusiasm for storms and sunlight as a showy nervous performance miss the point. Of course it is. There is a psyched up desperation to his art that does not make sense as a response to nature.
It is achingly theatrical, even phoney, but it is pursued with an energy and inventiveness that makes each painting a passionate search for meaning and purpose in the universe. That search is met only by the blinding sun, burning into the brain of Regulus, illuminating ruined cities, revealing the funnel of a steamship, the onrush of a locomotive.
Turner paints his own need to paint. His art reveals his need for art. Its heroism hits the buffers, his energy is swirled into one painted shipwreck after another. Out of the ashes of this Götterdämmerung I crawled away exhausted, wrecked, into the empty light of the modern world.
