Better late than never, Britain is finally waking up to German expressionism. It is only a few months since Max Beckmann transfixed the Tate, and now the Royal Academy has followed suit with a similarly arresting survey, devoted to Ernst Ludwig Kirchner. Incredibly, it is the first Kirchner show here in 30 years, and the first ever held in a British public gallery - and it shows what an exciting and complex talent our insular island has missed.
Kirchner was born in Germany in 1880 and committed suicide in Switzerland in 1938. Yet this compact but comprehensive display straddles only 13 years, from the advent of his career, in Dresden in 1905, to its glorious and dreadful climax in 1918. In this short time, his intense vision shifted from hedonism to decadence to hysterical decay, as Deutschland slid from imperial pomp into the "bloody carnival" of the First World War. It must have been a terrible journey, especially for an artist of such psychotic sensitivity, and this alarming record of his rise and fall, and the rise and fall of Germany, has the narrative pull of a gothic novel.
In 1905, Dresden was still a beautiful city, the Florence of the Elbe, but unlike Canaletto, Kirchner did not paint the architectural drama of its baroque streets so much as the erotic drama of its boudoirs. Decorated with African, Indian and Oceanic art, and inhabited by a similarly exotic array of models, Kirchner's studio was his sexual playground, too. "How you enjoyed sex!" he told his first great muse and lover, Dodo. "With you, I experienced it to the full, almost to the point of lunacy." A less sensual lunacy would overwhelm him in the awful years to come. In a comic metaphor for Dresden's prim disapproval of his bohemian aesthetic, he was accosted by a prudish policeman during one of the alfresco frolics that inspired his bucolic nudes, and narrowly escaped prosecution. Kirchner and his free-loving friends decided to decamp to cosmopolitan Berlin.
He fared little better in the licentious Prussian capital. The art school he founded attracted only two paying pupils, and his influential expressionist clique, Die Brucke ("the bridge"), fell apart. Yet here in Faust's metropolis, he created his greatest pictures. These claustrophobic street scenes, in which anonymous predatory men stalk debonair, disdainful prostitutes, captured the alienation of urban life and the amoral appeal of a brash new culture on the brink of apocalyptic collapse. As he revealed, "they were made at one of the loneliest moments of my life".
Loneliness is no bar to creativity, but insanity often is - and the war finally pushed Kirchner's fragile psyche over the edge. "I'll never be any good as a soldier," he predicted, and he was right. He volunteered for the artillery, to escape the wholesale slaughter of the infantry, but was invalided out before he even reached the front. During his descent into madness, he made some more fine paintings, including a horrific self-portrait, in uniform, with his right hand symbolically hacked off at the wrist. His postwar work never recaptured its former vigour. On the eve of the Second World War, distraught and terrified by his inclusion in the Nazi "degenerate art" exhibition, he mutilated his remaining artworks and then shot himself. "My heart is German and my art is, too," he said. "Germany has always failed to recognise her artists."
Kirchner's biography echoes the (self-) destruction of his fatherland, but his art is far too exuberant for this to be a purely tragic tale. His Dresden pictures are a joyous celebration of youthful pleasure, and although in Berlin his perspective shifts from libidinous lover to that of furtive voyeur, these fretful Meisterwerken still crackle with the thrill of what was then the world's fastest-growing city. Kirchner lived the life he painted, and throughout the compressed time-span of this frightening yet life-affirming retrospective, he surely lived (and painted) life to the full.
Only a few years after his suicide, Kirchner's Dresden and Berlin were both destroyed - but a lifetime later, both places are enjoying a cultural renaissance, and so this sombre story has a happy ending, of a kind. Who knows what he would have made of these resurrected cities? But he certainly would have found plenty of fresh subjects for his exhilarating paintings. As he himself said, "In spite of everything, I've achieved something. And when I'm not here any more, people will perhaps realise that I've taken something new from nature and introduced it into art."
So why has this fascinating and important artist been so neglected in this country? Of the 172 pictures in this exhibition, only one is from a British gallery. The answer, sadly, has a lot to do with our national preoccupation with the Second World War - yet during the past decade there has been a dramatic change. "Ten years ago, it would have been difficult to do this exhibition," says Jill Lloyd, who co-curated it with the RA's Norman Rosenthal. "The anti-German feeling after the war was stronger here than anywhere else, and it really has taken a couple of generations for people to be more open and understanding that these artists were also victims of the Nazi regime."
Reunification has made a big difference. "Now we can borrow all over Germany," says Lloyd. "Before, we would never manage to get paintings from Dresden, for example. It was just too difficult."And the art market has also changed. Sotheby's and Christie's hold German sales, and international collectors are now more aware of what German art has to offer. Our artistic compass has always been skewed towards France, but British art owes more to Germany than we might suppose. After all, two of our greatest living artists, Lucian Freud and Frank Auerbach, were both born in Berlin. "We who possess the future shall create a physical and spiritual freedom opposed to the values of the comfortably established older generation," wrote Kirchner in his manifesto for Die Brucke. Nearly a century later, it is still a pretty good mission statement for any young artist starting out today.
"Kirchner: expressionism and the city" is at the Royal Academy of Arts, Piccadilly, London W1 (info: 020 7300 8000) until 21 September