Christen Kobke: Danish Master of Light, National Gallery, London

A prodigy of Denmark's Golden Age illuminates traditional subjects with a heart-warming contentment

I have never seen Frederiksborg Castle, and, thanks to Christen Kobke, I hope I never will.

How could reality do other than disappoint? In the mid-1830s, Kobke, a master of Denmark's Golden Age, painted the former royal palace in North Zealand again and again; half a dozen of the pictures are in a small show of his work at the National Gallery. A couple of these are the views you might expect – the castle looming, castle-like, across a lake – but they are not the images of Frederiksborg that stop the heart. Instead, it is the pictures Kobke made looking out from the castle towards nothing very much – an ordinary village, a heron in flight, lemon-coloured sky – that stay with you, stored in a quiet corner of the mind.

This show of Kobke's work is subtitled Danish Master of Light, the kind of fluff, in normal times, to make you sigh and tap your foot. With Kobke, though, the cliché isn't one. Roof Ridge of Frederiksborg Castle, with View of Lake, Town and Forest (c1834-5) is precisely what it claims to be, or maybe less.

You can imagine what Kobke's older English contemporary, J M W Turner, would have made of the subject, never mind of the title. In the Dane's hands, though, Frederiksborg Castle becomes an incidental frame to the edge of his world, providing handy verticals – a turret, a chimney – to focus the eye on its rising horizontals: bands of roof-line, water, darkening land and pale sky, as abstract in their way as an Agnes Martin. The watchword here is order, and Kobke's light, undemonstrative, anti-dramatic, is part of the equation.

The word that springs to mind is Enlightenment. Although, by the time Kobke entered Copenhagen's Kunstforeningen as a student in 1826, the Enlightenment with a capital "E" was safely over, he was schooled in its virtues by his 80-year-old tutor, Christian August Lorentzen. But this coincidence of history doesn't altogether account for Kobke's light, which is quite different from his master's. Lorentzen's was a metaphorical light, like the shaft of Liberty that shines through the window of the titular court in Jacques-Louis David's Tennis Court Oath at Versailles. By contrast, Kobke's has only the single intent, which is to show the world as it is.

That sounds ordinary enough, although ordinariness in painting was anything but in 1834. Fifteen years after Roof Ridge of Frederiksborg Castle, with View of Lake, Town and Forest, Gustave Courbet would begin to make the works that came to define that school of art known as Realism. The term, of course, was nonsense. Courbet's reality, like his subjects, was grungy, his aim political; his light, too, was deeply selective, intensely partisan. Contrariwise, the light in Kobke's View Outside the North Gate of the Citadel (1834) has no moral weight at all. The Citadel, where the young Kobke's father was a master baker and he himself grew up, was recalled by the artist's contemporary, Hans Christian Andersen, as a den of poverty and vice. There is none of that here. Although Kobke's light falls on the bare feet of the boys fishing from the bridge, it has nothing to say about their bareness other than that it is there. No revolution is being fomented by his art, no comment made.

All of which is to say that Christen Kobke gives every impression of having been that unusual thing, an artist happy with his lot. Since this lovely show is in the Sunley Room and the Sunley Room is in the middle of the National Gallery, you might spend a pleasant afternoon trying to find a light quite as contented as Kobke's. Vermeer's seems charged by contrast, downright ominous. Poussin has the citric éclairage, but then his is a world of gods and heroes disporting itself on the Roman campagna. The Welsh painter, Thomas Jones, is nearer in time to Kobke and nearer in mood as well: his Wall in Naples has something of the Dane's happy clarity. But Jones has to go to Italy to find his subject, where Kobke's Italian trip resulted in the least likeable works in this show – seascapes off Capri that look as though they might be anticipating Impressionism in their splashiness but are actually just a bit cack-handed.

It is only back home in Denmark that he finds that domestic Arcadia which seems so very Scandinavian, a place where castles are there to look at villages from, where portraits can celebrate the average. If the winter has left you light-deprived, then I can think of no better antidote than this show.

To 13 Jun (020-7747 2885)

Next Week:

Ossian Ward heads to Compton Verney hoping to find fresh insights on the work of Francis Bacon