'If the artist has to explain his art then it becomes meaningless,' he adds gloomily. I press him further. As a painter he uses oils, but interviewers have only words.

To everyone's surprise, as the conversation is entirely good-natured, we reach a sudden stalemate. It continues until the three of us leave the gallery and go outside for a cigarette. Then we smile, and Em says his concept is not of shadows, but of love: his love for his family, for Saigon and for life.

These paintings that are so very dark, are really about light, he says. 'If you want to see the brightness of a lamp, then you have to see it at night.' The elements of his pictures - an earth teapot, a luxury green silk scarf draped on a chair, autumn leaves, a model (always his wife or a daughter) looking very serious - are just the skin of our metaphorical beast, he says.

'The picture is not the aim of the painting at all: there has to be a spirit behind it. That is what I would like to achieve, perhaps I have not yet succeeded.' He is equally unhappy about talking about his life. Like the lives of many of his compatriots it has been a confusing one, full of tragedy and uncertainty. A catalogue which mentioned he had been in prison was recently confiscated until the offending paragraph was removed from each copy. He does not mention this, nor does he want to discuss anything about his own life that is not about early studies at the National College of Fine Arts in Gia Dinh, Saigon, or about his happiness as a married man and a father.

'A person's life is not always smooth, it has its good points and its low points,' he says gently.

'I am a happy man: I love my wife and my children, I love the place where I live,' he continues.

'I try to express that in my paintings, I don't know if I have succeeded. When I use the word 'try' it sounds so wrong.

'The only thing that works is what comes naturally. You cannot force it.' His artistic eye first developed behind a medium format camera, and from that perhaps came his sense of the life and texture behind a piece of luxurious fabric.

Em's father was a professional salon photographer in Phanrang in southern Vietnam. During his childhood in the 1950s the house was full of clients preparing to pose for portraits. A traditional Vietnamese gown, a vase, a flower. These props used by his father to create a sense of tradition in the portraits the middle class commissioned for their posterity are still very much there in Em's work.

Later, with his father's blessing, he went to study art at the college, graduating in 1965, and remained in Saigon where he has lived ever since.

'I never wanted to take photographs again.

'My works are realistic but not photographic,' he insists.

'There is something about photographs that are close to real life in a way: although for a photographer and an artist to be good, they both have to have their feelings in their work.' His teachers were mostly French, teaching impressionism, realism and elements of modernism. So his own preferred style was not influenced by socialist realist art movements, he says.

Abstract art is interesting too, but less of a challenge, he says. 'It's just so much easier to put your feelings in there than if you are painting realistically.' He continued to paint, or at least to think about art, during the most difficult years after the war.

'In times of trouble, art finds a discrete place where it doesn't stand out,' he says, in partial explanation. Perhaps this is the real metaphor underlying his work: that art and love survive in the darkest times.

So what can be said about Em? He is 56, has a strong, thoughtful gaze that is non-confrontational. He smokes menthol lights, and has a long, greying, straggly beard that conforms to a romantic sense of what an Asian artist should be. But that just describes the skin. There is a tiger inside there somewhere.

Spirit: Towards The Millennium, 10.30am-6.30pm Mon-Sat. Galerie La Vong, 13/F One Lan Kwai Fong. Ends October 31