Click-rattle-bzzzzz! Dan Flavin's fluorescent sculptures stand as icons of minimalism, says Mark Irving. But a tortured childhood and a hefty dose of Catholic guilt may have more to do with them than you might imagine...
The taxi ride east from Manhattan through Queens and then out into New York's ragged suburbs towards JFK airport is a fragmented essay in disillusionment. Once the celluloid skyline behind you dissolves in the evening air to be replaced by a tangle of humdrum apartment blocks, sinister hospitals and gaudy cemeteries, the euphoria of Manhattan quickly evaporates. This is where even a passing knowledge of minimalism can really help. I say knowledge because minimalism is an art form you can't intuit without some coaching. Otherwise the pedestrian bridges that whizz overhead wouldn't seem unexpectedly beautiful. Not the bridges themselves, but the thin line of fluorescent lights that trace the dimming shadow of the bridge. They weren't meant to be beautiful, but that's the gift you can give yourself if you want your encounter with minimalism to last longer than the hour or so spent in an art gallery.

The encounter in question was with the work of Dan Flavin, the artist who made fluorescent light into art. Perhaps my retina was a bit burned out by seeing his retrospective at the National Gallery, Washington DC, the day before. Yet the discovery that minimalist art has this redemptive quality, that it can make the very ordinary a little less ordinary, beautiful even, that it can be at all generous, was surprising. Its record of reductiveness - all part of a macho discipline that seems rather male - suggested meanness, a parcelling out of meagre emotional rations. I think of Donald Judd and I see tightly pursed lips and a notebook of rules and aberrations: aesthetic fundamentalism supported by a niche, rich market.

In Washington, however, I'd been bathed in an optimism I would never have expected. This is Flavin's first retrospective in his native America and as such a milestone in the artist's posthumous reputation (he died aged 63 in 1996). For an artist to have their work shown in the National Gallery is to enter a pantheon from which it's almost impossible to be expelled and the exhibition signals the apotheosis of a pioneering minimalist whose oeuvre, while known through certain iconic works, has never before been properly assessed. Flavin's prices on the art market have shot up since the retrospective, with the sale at Christie's New York last November of untitled ("monument" for V Tatlin) - he never used capital letters for his titles - for $735,500, an auction record for the artist.

"As one of the most influential artists of his generation, the retrospective is the first time people - including contemporary artists - have got to see the range of work available," says Harry Blain, director of Haunch of Venison gallery, London, where an exhibition of several early works by Flavin opens this month. "It enables the market to add value to the works by knowing where they're located or what they're like. Although prices were growing beforehand, there's now a more aggressive pursuit of Flavin's work." The exhaustive catalogue produced by the curators of the US retrospective calms fears about dubious pieces - his work is made of ordinary light fittings and easily faked. It also underlines the importance of the valuable certificates Flavin produced authenticating each work and without which a Flavin is almost impossible to sell.

From outside the Washington gallery, I'd seen how the retrospective lent a nuclear glow to the heart of the capital. In the form of Flavin's untitled (to you, Heiner, with admiration and affection) (1973) - a repeating sequence of short green fluorescent lights arranged vertically and horizontally in overlapping frames along the inside length of a glazed wall - the glow was neural, alive. But this apparent life came from a man-made product, fluorescent lights: "a discharge tube," the dictionary states, "in which a phosphor on the inside of the tube is made to fluoresce by ultraviolet light from mercury vapour."

How is it possible to like a fluorescent light? The last thing I expected was to find them so warm. Walking around the exhibition I was met by a barrage of lights that produced an odd sensation, like being warmed up in a microwave perhaps. The discovery that fluorescents can command a space and not make you want to leave is enough to make you suspend your disbelief in the first instance. The artificial environment of exhibition spaces can often serve to bolster the proposition put forward by the work in question; but in the case of Flavin's work, the act of quarantining it within an exhibition of this kind amounts to salvation. In short, it saves it from just being lighting, by concentrating the everyday, the ready-made into something extra: it makes it art.

The proposition of the Flavin retrospective is clear: these lights have their poetry. But it also communicates the enormous discipline it takes for art of this kind to make it through the barrier of acceptability. In Flavin's case, this consisted of more than 30 years of very focused attention upon his materials of choice: light fixtures, light bulbs and space. I guess it takes minimalists much longer for their work to be recognised, for its shape and territory to be acknowledged by the rest of us (and by other artists), because the creative moves involved can often seem so slight as to be almost invisible. With Flavin, the space for movement would seem to be very small, given his determination to work with so few variables, but the retrospective reveals how much he could do with them. From arrangements of single tubes, ranks of tubes of different lengths, arrangements of coloured tubes, to tubes that project into our space and tubes that block the viewer's way entirely. Working with this seemingly simple palette, Flavin enables people to enter the space of the art while at the same time demonstrating the possessive demands of installation art. If you walk around the re-opened Museum of Modern Art you'll see how his pink out of a corner (to Jasper Johns) (1963) longs to be in space of its own rather than casting an embarrassed glow over neighbouring works.

It's this discipline that suggests a quasi-theological character to some minimalist work. Flavin hated being called a minimalist, but artists love to try to control the language used to describe them and their work. I know what Flavin said about critics - it's the most pointless job in America, art criticism is dreadful and useless, etc - but he was extremely anxious to shape what should be said about his work.

According to Steve Morse, Flavin's studio manager from 1991 and now the specialist called in to set up displays of his work, Flavin could chill the air with a chosen comment. But once he liked you, you were in. "He asked me to do something with one of his works and I didn't know why it was important and so he explained it to me. I then saw the work in a different way and he knew he didn't have to explain himself again."

If you read the text of the frank autobiographical sketch Flavin gave to the Brooklyn Museum of Art in 1964 you find a man armed to the teeth with cynicism and censure, albeit delivered with fearsome detachment. Much of the censure is directed towards his parents, but his underlying contempt for the Roman Catholic church is palpable throughout: "I was born (screaming) a fraternal twin twenty-four minutes before my brother, David ... of an ascetic, remotely male Irish Catholic truant officer whose junior I am, and a stupid, fleshly tyrant of a woman who had descended from German royalty without a trace of nobility." It gets worse: an abusive nanny; his repressive years at a junior seminary to which he and his brother had been sent by their father in order, Flavin claimed, "to fulfil his own lost vocation for priesthood" but from which Flavin fled having flunked his senior exams; a dulling period serving as an Air Weather Service Observer in Korea; before the slow - very slow - climb to success as an artist in New York.

When you look at Flavin's early works, you come across the inflections you expect to find in that make-or-break period before an artist finds his or her own language: homages to Van Gogh - the quintessentially "unrecognised" artist - and to James Joyce. It was Joyce who, through the character of Stephen Daedalus in A Portrait of the Artist as a Young Man, traced the experience of wrenching free from a stifling Catholic upbringing. There are some amusing confections produced during the late 1950s that poke fun at this upbringing - the best is a lamp, the base of which is made from a tin of tomato paste (the brand is "Pope") with a Christ figure as the filament. But the overall impression is that of a man feeling his way towards revelation. Yet there's one small sheet of paper in which you sense a light bulb, as it were, has switched on in Flavin's mind. Scrawling down the sheet are a chain of words written in the artist's spidery hand: "fluorescent/poles/shimmer/shiver/flick out/ dim/monuments/of/on/and/off/art" - all of which seem to spell out a road-map of the artist's future.

Flavin himself used the word "epiphany" to describe his eureka moment - his creation of the diagonal of personal ecstasy (the diagonal of May 25, 1963), an eight-foot fluorescent strip with gold-coloured bulb positioned on a wall at an angle of 45 degrees, with one end touching the floor. "The radiant tube and the shadow cast by its supporting pan seemed ironic enough to hold alone," wrote Flavin. "There was literally no need to compose this system definitively; it seemed to sustain itself directly, dynamically, dramatically in my workroom wall - a buoyant and insistent gaseous image which, through brilliance, somewhat betrayed its physical presence into invisibility." The language, with its compressed energy, is wrapped in the awe of discovery and self-discovery. For those who like to read the brushwork on a painting, Flavin's work is singularly unrewarding: "F96T12/GOLD/ SL - 75W - Made in USA" is all the legend the light bulb in this work has to offer.

Flavin's talent lay in his ability to use his very limited repertoire of materials to reference both a broad sweep of art history and contemporary politics. Many of his works are dedicated to artists living and dead - Henri Matisse, Juan Gris, Piet Mondrian, Ad Reinhardt, Sol LeWitt, Jasper Johns, Robert Ryman, Roy Lichtenstein - and Flavin cues your recognition of these artists' work through the adroit arrangement of coloured or plain bulbs. My own favourite is the four-tone vertical light piece dedicated to Matisse: the soft pink, yellow, blue, and green lights condense a palette you've seen in a hundred paintings. It's an in-house form of personal address by Flavin to people he clearly admires or seeks to outdo (as in Greens crossing greens (to Piet Mondrian, who lacked green) (1966), a room-sized installation that asserted Flavin's ability to "correct" Mondrian's neglect of the colour).

But it's in the pieces that reference political figures, be they presidential candidates or slain student protestors, that you sense something of Flavin the boy, someone who knew about oppression and poverty. His monument 4 for those who have been killed in ambush (to P.K. who reminded me about death) of 1966 - an installation of three eight-foot red coloured lights that hover malevolently in the corner - is truly astonishing. This was the period of the Vietnam War but it was also only four years after his twin brother David had died of polio and you sense a strong need in Flavin to memorialise in these works of light his awareness of death.

Light is never innocent or naively used in art. And while it's easy to make a connection between Flavin's work and that of the 19th-century artists of the Hudson River school, who developed a landscape style emphasising wide light-filled skies that celebrated the presence of the sublime in nature, Flavin resisted such comparison. As Michael Govan, director of the New York art institution DIA and Flavin specialist, explains, the artist "argued that you can't be lost in the sublime in the mid to late 20th century". This doesn't explain, however, Flavin's decision to buy a house in Garrison, upstate New York, right on the Hudson River and close to a natural landmark frequently painted by the Hudson River school. But then the dissonance between Flavin's professional life and his statements and the way he lived his private life is striking: his home was filled with artefacts referencing local heritage and, judging by the photographs, was a homely, traditional place. He married twice, with one son, Stephen, born in 1964. Tiffany Bell, Flavin's archivist, confirms he did have a few of his own works at the Garrison house "but they were rarely switched on". I'd already heard how some collectors of Flavin's work also tend to keep them switched off, turning them on only when guests arrive. "His work is stubborn and difficult in this way," says Govan.

The question of whether Flavin wholly abandoned his Catholic background would dog him to the end of his life. Early in the 1960s, he produced what he called "icons", a series of installations consisting of light bulbs and painted wooden containers mounted on the wall. Flavin's use of the term is wholly unWarholian - these works aren't about celebrity; rather, they reference unseen people and places and as such seem to be about memory and the function that shrines have in keeping memories alive. It's tempting to read something of Flavin's religious upbringing in all of this, but, says Bell, "this would be to misread his intentions. He wasn't seeking any religious revelation." Flavin's own account of the effect of his education suggests it played a wholly antithetical role in his creative development: "religion was forced upon me to nullify whatever expressive childish optimism I may have had left," he insisted in his autobiographical sketch. If anything, therefore, Flavin's ecstasy stems from his realisation that, at last, he had stumbled upon a form of artistic expression that he believed linked him to the work of past masters, such as Duchamp, the pioneer of the ready made, and Brancusi, the inventor of the endless column.

That said, his last personally directed work was a light installation completed in 1996 for Santa Maria Annunciata Chiesa Rossa, near Milan. At the time, the artist was suffering the awful affects of diabetes (he had had parts of his feet removed in an operation in 1987) and was prone to what his closest colleagues saw as bouts of seemingly self-destructive behaviour. His concentration, however, didn't lessen in intensity: he arranged for the Modernist church to be flooded with colours and in selecting golden lights for the apse, Flavin revealed his deep-set understanding of ecclesiastical spatial hierarchies and their ritual connotations. The unusual commission - unusual, since Flavin's feelings about his Catholic upbringing were well known - came about through a fortuitous approach made to Govan by people close to the church. Since Flavin's death, the project has been seized upon by Catholic observers as evidence of a soul reclaimed by the church; but Govan is clear that, rather than the project representing some kind of spiritual homecoming for a prodigal son, Flavin admired the building for its architectural qualities and "saw his work in the tradition of art". It comes as a bit of a surprise, therefore, to learn that Flavin was completing an installation for the Calvin Klein store in Manhattan, designed by British architect John Pawson, at exactly the same time. This time, the lights were a blood red. It's tempting to read a delicious play-off in this contrast of commissions - one sacred, the other avowedly profane. "Irony was very important to Flavin," says Govan. But then Pawson's work exploits the language of sacred exclusivity and expensive self-denial, so perhaps the contrast isn't that great.

What is striking about this tussle to "own" Flavin - a tussle between the priests of the Catholic faith and those guardians of contemporary art history - is that it demonstrates how thin the line is between both concerns. Minimalist art, with its charged attentiveness to surface, volume, space and tone, invites a contemplation of the ineffable that doesn't seem a million miles away from the devotional practice of religious faith. Check out the dealers, curators and writers running the contemporary art field and it's not hard to see them as acolytes serving a mutually self- sustaining value-system. Then again, perhaps some people can't really believe in the purpose of Flavin's aesthetic discipline - it can't all be about lights, can it? It becomes necessary, therefore, to inject a more easily acceptable intent - that of a questing, dislocated soul - into the work. "He hated the short circuit to `meaning'," says Govan. As Flavin might have said, short circuits prevent illumination. m

`Dan Flavin: a retrospective': The Modern Art Museum of Forth Worth, Texas, USA (00 1 817 738 9215) 27 Feb to 5 June and touring. `Dan Flavin: Works from the 1960s': Haunch of Venison, London W1 (020 7495 5050), Sat to 16 March