CULTURE SHOCK:Dutch painters of the 17th century had to occupy safe - or religious - ground, but Gabriel Metsu saw this as a springboard for innovation

THERE ARE MANY good reasons to visit the National Gallery of Ireland’s major new exhibition of the paintings of the Dutch 17th-century painter Gabriel Metsu.

The most obvious is that it is simply delightful. Metsu might not have the breathtaking luminosity of his contemporary Jan Vermeer. But his range of subjects and emotions is much more astonishing: from vegetable markets to sumptuous mansions and from the deathly pallor on the face of a sick child to the gilded filigree on a rich merchant’s opulent wallpaper. Where Vermeer’s images have a static, ethereal beauty, Metsu’s are full of irreverent life: lustful leers, defiant stares, the knowing glances of servants, dogs chasing cats in the corner of a grand canvas.

Beyond these basic pleasures, however, the Metsu show has a specific resonance in the context of Irish culture. Perhaps the greatest cultural cliche of our island is the association of Puritan Protestantism with dourness. This tends to be taken for granted by cultural Catholics, but it has also been largely internalised by some Protestants, who seem determined to live up to the stereotype of killjoy sexlessness.

But hang on a minute: Metsu and Vermeer are near contemporaries of another Dutchman, one who significantly shaped Irish history: William of Orange. And Metsu, Vermeer and so much of the golden age of Dutch painting are unthinkable without Puritanism. It is Calvinism that defines not so much what they do as what they can’t do. And, as the Metsu show reminds us in such a pleasurable way, that prohibition is also a wonderful liberation. It does not produce dourness. On the contrary, it creates a whole new visual language, a new sense of what is worthy of being depicted.

In the 17th century the Netherlands were shaped by the great religious divide of Europe, the southern part – now Belgium – remaining Catholic and the Protestant merchants of the northern towns breaking away from Spain.

What has this to do with painting? Everything.

Within a Catholic culture, patronage for painters still comes from the Church. Visual imagery is still plugged into the great traditions of biblical and religious representation. Thus, in the Catholic Netherlands, the great Peter Paul Rubens is giving astonishing new life to traditional biblical scenes. The large-scale dramatic imagery and violent emotion of an episode such as The Massacre of the Innocentsis still available for Rubens to use for his overwhelming masterpiece. But in the north, painters have to do something else. There are no Church patrons, and religious art is a dangerous business in an iconoclastic Puritan culture.

Metsu is a very interesting case in point because he was most probably a Catholic. (His family were southern, and his wife is known to have been a Catholic.) You can see very clearly in the National Gallery's exhibition that his instinct as a precocious young painter in Leiden was to work within the inherited tradition of religious iconography. The earliest works are a drawing of the Resurrection of Christ and a version of the story of the rich man and the beggar, Dives and Lazarus, from St Luke's Gospel. And it is just as clear that he might have gone on to become a great religious painter: a late Christ on the Crosshas all the necessary dramatic emotion and compositional boldness.

But Metsu couldn’t be a Catholic painter. Without the patronage of the Church, art had to function in the marketplace. The merchants and burghers who were the buyers that a professional such as Metsu had to please were either Protestant or, if they were Catholics, they were too discreet to want to hang huge, explicitly religious canvases in their drawingrooms. Like so many of his contemporaries, Metsu had to occupy much safer ground: family portraits, domestic scenes, picturesque images of the poor, comic genre paintings.

And yet, if this robs painting of much of its classical grandeur, it also stimulates innovation. There are three remarkable transmutations that happen in Metsu’s work as he moves away from his early network of Catholic patrons, and they produce some great paintings.

Firstly, he learns how to turn religious icons into "modern" domestic scenes. The stunning The Sick Child, from the Rijksmuseum in Amsterdam, is one of the glories of the Dublin show. It functions first as an immediate and heartbreakingly tender image of human compassion – a woman holding a wan girl on her lap. Only after a while does it strike you that it is also a version of classical religious images of the Virgin – the Madonna and Child and the Pietà.

The second wonderful thing that happens is a shift away from big drama to a much funnier and more subtle kind of theatre. Metsu is brilliantly suggestive, not least in relation to sex. The faces of servants speak volumes. Take two paintings that show essentially the same scene: a male lover invading the privacy of a young woman's boudoir. In one, A Man Visiting a Woman Washing Her Hands, the focus is on the servant in the middle who is pouring the water for her mistress. Her face is full of barely concealed devilment, as though she can't wait to get below stairs and dish this latest bit of dirt. In another, The Intruder, the woman being visited looks prim but her servants have collusive smiles. They know different.

The third great transformation is that the move away from sacred subjects is also a move away from the centrality of the subject itself. Metsu still has narratives and is a master of realistic detail. But as EH Gombrich observed, "the Dutch specialists who spent their lives painting the same kind of subject matter ended by proving that the subject matter was of secondary importance." What really matters in a wonderful painting like Metsu's A Woman Reading a Letteris not the realism or even the allegory that grows out of it. It is the light towards which the woman turns the letter so she can read it. Metsu directs our attention to that glorious stuff that makes the world visible and in so doing joyfully celebrates the visible world. And it is Puritanism, in the end, that makes this celebration possible. Free tickets to the Metsu show should be given to every Orange lodge – for this, in its own way, is an exhibition about their culture.