For nearly two-thirds of his life, Edward Hopper lived and worked in a top floor studio overlooking Washington Square in New York. He didn't have a fridge or a toilet, and regularly hauled coal up four flights of stairs for heating, but there was a skylight, and the room was exceptionally bright. On the far wall, between the windows and beside his easel, he placed a mirror; when he looked at it he could see into the studio behind his, which was occupied by his wife, Josephine Nivison Hopper. She, in turn, was watching him: on the walls of her now empty studio there remains a portrait she painted of Edward Hopper, his face bleak yet monumental against a thick white background. Into the impasto paint around his head Jo carved a peculiar shape - the halo of a saint, or perhaps more fittingly, a martyr.
Although they went on painting trips from time to time - to Massachusetts, Mexico, or Maine - for the most part the Hoppers remained cooped up in this small space, seeing few people and eating out of tins - conditions that were perhaps inevitably explosive. 'They spent almost 24 hours a day, seven days a week together for three years,' says Gail Levin, an art historian who has written 10 books about Hopper, 'that's hard for any couple.' Levin has had sole access to Jo's diaries, in which she recorded violent arguments: Jo scratched Hopper and 'bit him to the bone', he 'cuffed' her, slapped her face, banged her head against a shelf and left her with bruises. On their twenty-fifth wedding anniversary she told him they deserved a 'croix de guerre - a medal for distinguished combat', and Hopper responded by making them a coat of arms out of a rolling pin and a ladle, joking about the honour of mutual domestic violence.
When she married Edward Hopper, Josephine Nivison was 41, and had been painting successfully for 16 years. Her work had been shown alongside that of Modigliani and Picasso, Maurice Prendergast and Man Ray. She regularly sold drawings to the New York Tribune , the Evening Post and the Chicago Herald Examiner . In 1924, the year they got married, a New York Times review of a group show at the Brooklyn Museum singled her work out for praise over that of Georgia O'Keeffe and John Singer Sargent. Jo recommended Edward Hopper's work to the curators of that show, and when they bought one of his paintings after the exhibition had ended, it was only the second he had sold in 10 years. As a result of the exposure she had secured for him, Hopper was given a sell-out solo show by the gallery that would represent him for the rest of his life.
When the Hoppers embarked on their hermitic existence, however, their influences fused to curious effect: as his palette borrowed some of her bright hues he became a runaway success, and when she began to emulate his style she lost all recognition. In the absence of personal reward Jo Hopper exerted such control over Edward Hopper's work that she came to see it as a collaboration. They had no biological offspring, but Jo repeatedly referred to her husband's paintings as their 'children'. She wrote that one of his canvases, New York Movie , was shown to his gallerist and 'greeted like a newborn heir'. She referred to her own paintings as 'poor little stillborn infants', 'too nice to have been such friendless little Cinderellas'. 'I don't much like them,' she told a curator, 'but how sad for them if even I forsake them!'
'Of course,' Jo wrote, 'if there can be room for only one of us, it must undoubtedly be he. I can be glad and grateful for that.' She kept careful records of every painting Hopper produced and sold, she wrote practically all his correspondence, and she began writing her diaries just months before his first major retrospective at the Museum of Modern Art, possibly perceiving a ticket to posterity. Perhaps most significantly, however, she jealously insisted on being the model for every single woman he painted.
From 1924 to his death in 1967, Hopper painted women who were shadow-faced, round-contoured ciphers. In the world of his imagination, they stayed up all night, poring over cups of coffee, lost in thought at the movies, undressing next to a radiator or lingering in the office with their boss, permanently stuck in some noir urban peepshow. Hopper's women never age, but his wife, their only model, was not so immune. After 25 years of marriage, she bemoaned 'time passing, passing, drop by drop of one's life blood - hair greying, fashions changing, an entirely new slant on art rampant and 25 years of my life gone'.
A bedraggled nude staring out of a window in 1926, a woman in black reading on a train, an usherette in a cinema, a redheaded 'nighthawk' in 1942, a blonde on a bed a decade later, a buxom young secretary in an office in 1962 - Jo Hopper was all of these women, and none of them. 'He transformed her,' Gail Levin explains. 'She trained as an actress - she had acted with the Washington Square Players - and it was a collaboration that was very productive for them. She wrote about burning her leg on the stove while posing nude for The Girlie Show, and she was very proud of it.'
To an extent, the Hoppers had the characters they created for company. Jo would invent names for them, and make a note of them in the record books. Then they would gossip about these fictional characters' habits - would the outstretched, barefoot figure in Excursion into Philosophy have worn comfortable sandals or four-inch stilettos? (Guess which fantasy was whose.) But The Girlie Show is particularly strange - a red-headed stripper strides brazenly across a stage in silver shoes, her face curiously masculine, her cartoonishly round breasts topped by bright scarlet nipples.
Elizabeth Thompson Colleary, who is working on two books about Jo Hopper, began her research when she found out that the model for The Girlie Show was Hopper's wife. It is, she says, 'one of the angriest paintings I've ever seen'. What was going on? 'I'm so excited,' Jo wrote in 1959, 'He has me stretched out in back with not a stitch on - playing dead.' She fantasised about the man depicted in the foreground of the work in progress: 'Did he kill her? Can't tell yet.'
In a telling caricature drawn in 1934, Hopper depicted Jo as an invisible woman, her earrings, collar, cuffs and shoes dotted around a featureless blank space. Did he mean she was an empty canvas, to be built up out of fantasy? Or did he mean she was apt to disappear? Was Edward Hopper transforming his wife, or erasing her?
When Jo Hopper died, she bequeathed all of Edward's work, as well as all her own, to the Whitney Museum - over 3,000 pieces in total. That was in 1968, and until recently, it was thought that Jo's work had been discarded or destroyed. But four years ago, Colleary discovered about 200 Jo Hoppers in the Whitney's basement. Colleary says Jo was an 'uneven' artist, but in general she thinks the work is good: 'I said to myself, "I will not resurrect this woman solely on the basis of the fact that Edward Hopper was her husband."'
Throughout her diaries, Jo Hopper's main complaint was that her husband was not supportive of her work. ('Isn't it nice to have a wife who paints?' she once asked him, rhetorically. 'It stinks,' he replied.) But it's not hard to see why Edward Hopper might have been wary of recommending his wife's work. Quite apart from the nepotism, it was nowhere near the standard of his. Whenever she showed it to a gallerist or collector later in life, she received a fairly negative response. So, although it's very possible that her private gripes had some foundation - Hopper could probably have been a more supportive husband (he patronisingly referred to her ability as 'a pleasant little talent') - there were plenty of opportunities for her work to be snapped up had it been considered good enough.
So the question is less to do with misogyny or undermining than with the quality of Jo's work itself. Was it merely that her style failed to change with fashion, or did something happen to Jo Nivison's work when she met Edward Hopper that meant she would never fulfill her early promise?
Colleary believes something did happen. Prior to meeting him, Jo painted small, bright, fauvist oils that were, in Colleary's view, 'expressions of her vibrant personality. Her pre-Hopper work is definitely the strongest - there's a spiritedness to it that is entirely her own. Her voice as an artist didn't come through when they were side by side.'
It was a curious fact of their relationship that Hopper not only influenced Jo's style but also her choice of subject. He would not allow her to drive, so they often ended up sitting next to each other, painting exactly the same scenes. Except that they weren't the same. On one occasion they painted a travelling circus together, but the only indication that his and her paintings bore any relation to each other is the gazebo that figures in both, and a line of rocks in the foreground. Each is a literal continuation of the other, yet in terms of mood they couldn't be more different. Hers is a yellow-striped circus tent, framed by bright, feathery-leaved trees and painted in watercolour. His is in heavy, brick-toned oils - the back of a circus wagon and a black car, seen as if creeping up behind the scene of a crime. The most gripping thing about the distinction is the way in which Hopper so clearly lived in a narrative world of his own imagining, whereas Jo remained tethered to the everyday.
Ever since Gail Levin rescued Jo Hopper from oblivion by quoting from her diaries, there has been some debate about how literally to take Jo's words. Barbara Novak, who along with her husband, Brian O'Doherty, was among the Hoppers' closest friends, explains that Jo 'saw the world through a barbed-wire screen of resentment'. 'These tirades were part of her eccentricity,' Novak tells me, 'she was mad, but gloriously mad.' 'She was a brilliant woman, an extraordinary woman,' O'Doherty adds, 'without a pink of humour.'
Given that the Hoppers were so sealed off from the world, Jo's diaries were the only place she could vent her frustrations. She clearly gave as good as she got - Hopper drew caricatures of her scratching him while he stood quiet and saintly, and of her refusing him food or sex. He was laconic, quiet, and chronically fatigued. She was a bundle of bitter energy. 'That Ego is so impenetrable,' she wrote of Hopper in 1946, 'Those lighthouses are self-portraits. At two lights [at] Cape Elizabeth, it was pitiful to see all the poor dead birds that had run into them on a dark night. I know just how they felt.'
Jo was a virgin when they married, and was shocked by the lack of pleasure there was for her in sex - 'the whole thing was entirely for him, for his benefit'. Since she was, she wrote, 'forbidden to consult with other women over the mysteries', she was left feeling 'so subnormal - not enjoying attacks from the rear!'
Nevertheless, the Hoppers stayed together, when they could have left at any moment. They met as mature adults, they knew how to live alone. But they needed each other. 'Ed is the very centre of my universe,' Jo wrote. 'It's such blessedness that Edward and I have each other. Surely I'll be allowed to go when he does.' Edward Hopper 'went' in 1967; he was, Jo told a friend, 'very beautiful in death, like an El Greco'. She said she was left feeling like an amputee, and died less than 10 months later.
Barbara Novak tells a story about a party she and O'Doherty threw in the Sixties, towards the end of the Hoppers' lives. Edward and Jo were the first to arrive. They sat down next to each other on a settee, and as the other guests - many of whom were the most successful artists of that new generation - piled in, they thought the Hoppers seemed happy and left them alone. Halfway through the party Novak turned to look at them and saw that a large empty space had been left around the Hoppers' sofa. It was an image straight out of one of his paintings: even in a crowded room, they radiated isolation - together.
'We don't know what she died of,' Novak says when I ask about Jo. 'I think she died for lack of him. And,' she adds, 'he would have died for lack of her. It really was a folie à deux.'
· Edward Hopper (sponsored by American Airlines) opens at Tate Modern, London SE1 on 27 May and runs until 5 September