Close-up and personal On the eve of his show at the National Gallery, Bill Viola tells Doris Lockhart Saatchi about video art with added passion

BIll Viola's art is famously difficult. And not just because of the content. To begin with, the American artist makes video art, a form that requires time on the part of the viewer. And that is something contemporary audiences seem reluctant to part with. In a recent and curiously ill-reasoned Sunday magazine article, one British critic even pronounced that video art "can't be proper art" because "it takes too long". Research indicates that, on average, museum visitors spend 30 seconds in front of each work of static art. That's not much for a photograph or painting, say, but it doesn't begin to do justice to a video tape or projection that may run for 20 minutes.

Viola's work is also particularly tough to deal with, at least compared to the quick-fix output of Cool Britannia, because it depicts in intimate physical detail the most private human experiences and evokes strong emotional responses - the kind of responses that haven't been fashionable in art for some time. "I want," says Viola, as we discuss this prior to the press launch of his new London show, "to part the curtain that is normally drawn over the most mysterious moments in life." If that sounds like New Age rhetoric or religious exhortation, you'll have to take my word that it doesn't sound that way when Viola delivers it. Granted, he is from California (born in 1951, he lives in Long Beach, with his two sons and his wife, arts administrator and photographer, Kira Perov) and admits to such influences as Buddhism, readings from the Egyptian Book of the Dead and studies of the ancient Greek idea of the "pneuma" or "breath of the cosmos". But he comes across in person as an intelligent, humorous individual with a professional interest in the inner lives of his fellow human beings. Like a psychiatrist, perhaps, or novelist, but not an ageing West Coast flower child.

As if its form and spiritual content weren't offputting enough, Viola's work relates in no uncertain terms to Renaissance paintings, not normally a favoured subject of contemporary art aficionados. Yet Bill Viola is a huge success. When an exhibition of his work was presented in London a few years ago at the f Anthony d'Offay Gallery, 50,000 people came to see it. His piece The Messenger was installed to much acclaim for a month in 1996 at Durham Cathedral, and his 1993 installation at London's Whitechapel Gallery drew rave reviews.

Given the influences and concerns in his work, it is not entirely surprising that Viola should be the first contemporary artist to have a solo exhibition, 14 works collectively called The Passions, at London's National Gallery, or that those works should seem right at home in the Sainsbury Wing, with the museum's collection of 15th-century devotional paintings.

Viola's own artistic conversion dates from a visit to the Chicago Institute of Art in the Seventies, when his father was dying. His response to a Renaissance painting that he saw there was to break down in tears. "For the first time in my life," he says, "I realised I was using a piece of art rather than just appreciating it." As a result Viola developed an interest in the nature and expression of human emotions, such as the question of whether crying is a sign of suffering or release from it. "Look at the poses in early art," he says. "They come from a deeper place - they're part of our natural physical reactions." In other words they're instinctive, and Renaissance artists were very good observers of human behaviour. Since then, he has sought to make art that is a starting point for meditation or a deep internal experience and which, in doing so, appropriates the techniques, visual references and, above all, explicit emotional content of paintings made half a millennium ago.

Until that pivotal moment in Chicago, Viola had been, as he puts it, "messing around" in the technical department of Syracuse University's School of Art in New York state, playing the drums in a rock'n'roll band, studying photography - which, he says, he "didn't do that well" - and making installations that included images on TV monitors and performance. What came out of those years was a predilection for the moving picture that for him is more closely related to music and sound than to painting and photography. "My training as a visual artist didn't teach me about my work," he says. "I learnt about the structuring and ordering of events in time from music." Viola has been making video art for the past 20 years, focusing on what he has described as an idea of the human body that "teeters" between physical and spiritual form. His early work led first to a show at an experimental space in Lower Manhattan - where he met video art pioneer Woody Vasulka, described by Viola as a major influence, along with Nam June Paik - and, eventually, to his being chosen to represent the US at the 1995 Venice Biennale.

The show at the National is Viola's first major one-man exhibition in this country, but not his first appearance there. In 2000 the gallery's then-director Neil MacGregor conceived a project in which 24 contemporary artists (including Cy Twombly, Jeff Wall, Claes Oldenberg, Lucian Freud and Louise Bourgeois) were asked to respond to a work of their choosing in the museum's collection. Viola's response was a rear-projection video in which he showed against a plain dark background and in extreme slow motion a group of five dramatically lit half-figures suggested to him by the onlookers in Hieronymus Bosch's Christ Mocked. Viola's piece, called Quintet of the Astonished, generated more comment than any other in the show and ultimately inspired a collaboration between the National Gallery's curator, Alexander Sturgis, and Los Angeles' Getty Museum. Back in 1997 Viola was invited to take part in a Getty Research Institute f programme exploring the subject of emotions. That experimental research resulted in The Passions, which opened at the Getty Museum earlier this year. The National Gallery's version contains much of the work in that exhibition (including Emergence, a new piece which the Getty commissioned), but focuses more on those Viola pieces based on paintings in its own collection, which will also be displayed nearby.

The Greeting, a 1995 sound and video installation that refers to The Visitation by the 15th-century mannerist Pontormo, is the earliest Viola work in the exhibition and the first piece he made which was visually and formally inspired by an earlier painting. It also represents Viola's first use of professional actors. Before that, he had usually turned the camera on himself, friends and family - the Whitechapel installation memorably featured Viola's filming of an elderly woman on her deathbed and a young woman giving birth.

Contrary to the normal practice of contemporary artists who work on a "subject-and-object" basis, going into the studio and making (or having made for them) the piece they envisaged, Viola's output is heavily driven by the actual process. He has assembled a small company of like-minded souls with whom he improvises. The results - in the piece Silent Mountain, for example - are occasionally so intense that they appear to be choreographed. When I raise this as a possible criticism, Viola tells me this piece is in fact performed by dancers, but is adamant that they weren't directed in their movements and emoting.

However, the presentation of "acted" emotions still raises questions of authenticity for some. Viola answers by pointing out that actors train to tap into their own genuine emotions at will and claims as an example that the crying actor in Man of Sorrows was grieving for his own dying father. Curator Alexander Sturgis simply defends Viola's practice as the necessary compression - or distillation - that defines every art form.

Virtually every piece in the National Gallery show offers an insight into not only Viola's methods and means but also the earlier work he has taken as his starting point. Quintet is a perfect example of Viola's use of lush, muted colour and chiaroscuro lighting that recalls much 16th-century art without copying it. As Sturgis reminds us, Six Heads and Dolorosa derive from 15th-century examples of the development of imagery such as the weeping Virgin that was what we now call the dramatic close-up. The image is so compelling because we know from scientific research what Renaissance artists knew instinctively, that human beings cannot help but read another human face. The space in Catherine's Room, a video on five wall-mounted flat-panel LCD displays, is structured by architecture, just as in Renaissance altarpieces architectural framing is used to distinguish episodes in a Christian religious narrative.

The Crossing of 1996, meanwhile, shows different images on both sides of a free-standing screen and introduces the two recurring elements, fire and water, that appear frequently in early religious work and in Viola's pieces. With The Crossing, from one soundtrack we hear the roar of a raging fire or of flooding water depending on which image we are looking at. On the water side, the figure of a man dressed in pale clothes is evanesced by a torrent to a ghostly form that slowly raises its arms, a gesture that can be seen as either supplication or blessing. The "storm" then subsides to a glow and, finally, darkness and silence. Throughout Viola's work, water falls, water rises. Matter coalesces, substance dissolves. Fire engulfs, fire consumes. For him, water and fire represent means of purification just as they do in religious iconography, but Viola also makes use of both elements technically as devices to dissolve and meld his moving images.

For Viola, constantly improving image technology and what it enables him to do is a driving force. Recently, he remembers thinking while trying out a new piece of equipment, that he was not working with video anymore. "There were no scan lines on the screen," he recalls happily. Instead, he says, "I was falling into the image." Viola defines his ideal in technical terms as the disappearance of the means of delivery so that the feeling and meaning of the work carried by the image passes to the viewer as directly as possible. Sturgis notes the extraordinary quality of the surfaces of Viola's recent images, achieved in part because the texture of an LCD screen is more like a painting than a photograph, and compares them to the highly finished surfaces and hyperrealistic imagery of early northern-European painting. But it is this polish of Viola's images that even some of his admirers call into question, wondering aloud if the content is obscured by the overly perfect presentation. Sturgis has the last word: "Even if you don't feel moved or react emotionally, the pieces are visually mesmerising - this is the first time that moving images have been of this quality. Seeing Viola's work is genuinely seeing a new kind of picture."

Pessimists say that Viola's art is the story of individuals being overwhelmed by man-made and natural forces. "We live in an adversarial world," replies Viola, "and I am interested in individual and collective responses to crisis." But for someone who sees life as difficult, Viola seems remarkably free of any trace of existential angst. "What carries me forward," he says, "is the relevance of the deepest, most private experiences to all humanity." What his art must be "about", then, is empathy, compassion, connection. Now, that is difficult. E

'Bill Viola: The Passions' (supported by the Genesis Foundation and Barco) is at the National Gallery, Trafalgar Square, London WC2 from 22 October to 4 January. (As part of the National Gallery's 'Wednesday Lates' series the exhibition will be open until 9pm every Wednesday with live music, bar and special ticket offers, tel 020-7747 2885 for details.) The catalogue of the exhibition, 'Bill Viola: The Passions', will be published by the J Paul Getty Museum (£57.50 hardback, £34.50 paperback) on 16 October.