I can remember everything in Frida Kahlo's bath: the tiny naked women, curving spikes of leaves, the tightrope with its snake and dragon fly. My feet are like hers, splayed against the end of the bath, toes peeping out of the water, the nails radish red, their reflection two flat fish with stumpy tentacles.

   I spend my time memorising things like this. It must have started in childhood with that game where you gather household items on a tray and see who can recollect the most, but it's turned into an addiction. I can recite the contents of trolleys at supermarket check-outs - olives, toilet fresheners, two for the price of one shampoos; plants amassed in a front garden - agapanthus, star of Bethlehem, verbascum, salvia; or elaborate meals on a restaurant menu - anything to fill the blank.

   Now, leaning forwards to reach the well polished taps, I have to push aside the other images from the bath: leaking shells and tropical plants, an empty yellow dress, a bird of Paradise on its back, a tall white skyscraper inside a smoking volcano, with a human skeleton, uncannily alert at its base. Not to mention the roots creeping up Frida Kahlo's legs: free-floating umbilical tendrils that curl and coil, looking for something on which to fix.

   `Are you getting out?' Ewan asks. I don't know how he knows I've moved. He hasn't turned round from his computer screen.

   `No. I'm topping it up.' I adjust the shining gold taps, with their moulded handles, and an extravagant jet of hot water cascades into the bath. It's the deepest soak I've had for months. At home I'm on a metre. `Would the TV bother you?' I wonder, still crouched forwards in the almost tropical heat, my hair dripping, body sodden.

   `Go ahead.' And Ewan carries on hammering away at his lightweight keyboard, as deftly and devotedly as any pianist.

   With a defiant sense of idleness I press the switch on the monitor and sink back into the perfumed water. Since the bath oils are supplied by the hotel, I've used a little of them all: bergamot, juniper, geranium, cypress, lavender. Why not? How often do you get to stay in an erstwhile country house, with a free-standing bath in the middle of your lounge and a large TV screen only inches from the taps?

   `She had a wonderful education. She had opportunities I never had. Do you have any idea how it feels, knowing your daughter is stripping off in public? Do you know how it breaks my heart?'

   The afternoon's shrill TV schedules care nothing for my hunger for peace, nor beauty. It's one of those audience participation debates a'la Jerry Springer and Oprah Winfrey, only being English, is more embarrassing - the hostility less well managed, the presenter out of her depth as the venom slips from spice to spite. A weary-looking woman is complaining about her daughter, who has abandoned school teaching for a more lucrative career as a stripper. When the girl herself appears, buoyant and laughing, she has curves that will stay in the right places for just a few more years, and a large silver ring through her nose, waiting to be led away like a prize heifer.

   `How could you do this to me? How could you let yourself go?'

   The mother wrings her hands as the studio audience heckles, one half siding with the parent as guardian of morality, the other defending the daughter's freedom of choice.

   I recline back further, letting my ears be slowly deafened by water, hair spreading round me like seaweed as my fingers tease out the strands. This is what everyone's been saying to me. You should get a grip on yourself, Louise. You mustn't let yourself go. Some of our expressions are so strange. Go where? Backwards, upwards, into thin air, off the beaten track?

   The water's muffling the worst of the raucous TV, but now there's an additional trace of new sounds coming in, footsteps on the bare boards in the room, and when I peer over the side of the bath - it's pure white enamel, deep and wide, on four carved antique claws like griffins' feet - there's a pungent smell of fresh coffee and a youth depositing a tray of silverware onto the low Danish table. He's as graceful as a heron, thin-faced, slender and still, yet when his eyes briefly meet mine, there's a look in them I'm too fuzzy with the heat to fathom. What is it? Envy? Pity? Misogyny? Contempt?

   Only when he lingers slightly by the desk, staring down a moment too long at the nape of Ewan's neck, do I think I understand. For I adore it too: that wonderful concave at the base of his skull where the hairline shows bone meeting sinew. How could I not? Wasn't I pressed against it for so many months, curved against his spine like a sea horse? But before I can gesture to the guy, before I can call out any encouragement - 'Feel free, go ahead, we're not lovers' - the panelled door has been tenderly opened and shut. And all this time Ewan has been sitting there unmoved, unwittingly typing.

   `I'll pour you some coffee in a minute,' he says, without turning round.

   `No hurry,' I reply, my skin baby soft as I sink deeper into the liquid heat, the aromatic oils ample compensation for my own lack of occupation. `I'm quite happy.'

   Ewan, of course, has done very well - if you measure well by the number of digits in your bank account. He's a trouble shooter for big corporations, a kind of multi-national therapist. He helps them identify the blocks stopping them reaching their targets, then - another inveterate list-maker - he collates the information into columns and boxes with neat bullet points marking goals, obstacles and strategic enablers. Is it gender that's made us so different? I mean, why have I ended up collecting Frida Kahlo's nightmares, or the contents of someone's trolley or window box, when Ewan can so lucratively recycle the worst dreams of the World Bank or CIA?

   Not that I'm complaining. If he weren't paid so absurdly well, I wouldn't be lying here in this opulent hide-away, up to my neck in these fragrant unguents. For I have to confess I've done extremely badly - if by badly you mean the reluctance with which you crawl out of bed each morning, or the tardiness with which you lurch through the day.

   I used to be in the world more. I trained to teach art in a secondary school, which is how I know so much about Frida's Mexican paintings. That surreal self-portrait, What the Water Gave Me, is amongst my favourites of hers - reminiscent of Hieronymus Bosch, the way she collects objects, her legs and feet surrounded by things that are half alive, half dead, in the bath.

   But this last couple of years I've not been able to work. No one's identified exactly why. Colleagues call it at best psychosomatic, at worst malingering; friends attribute it to post-viral syndrome, though it's too far off the map to let me claim benefit; others use the grey blanket term depression. Not that I'm attached to what it's called. I no longer believe words reach the most important things.

   Some days I'm lucky if I can drag myself to the park. There's a wooden bench by the huge ash tree near the lake where I sit and watch the seasons slide into each other like decks of cards. The water moves from liquid to ice, then from emerald to sienna with a brown poultice of leaves. Time has so unhooked itself from the clock it hardly seems to exist at all. Only yesterday the seed pods on the ash tree were hanging in bunches of soft green keys and now they're rattling and brittle, ready to fall.

   `I don't know why you don't get a video,' Ewan grumbles, coming over from the table. `The hotel's got a great selection. You only have to ask at reception.' He puts my sweet milky coffee on a ledge and stands by the bath with his own, which is purposeful, black and bitter. Above the gold taps the two sides of the studio audience - moral bigots versus sexual permissives - continue to hiss and jeer and boo. `How can you watch this rubbish?'

   `Turn it off if you like,' I concede. `It's only for the white noise.' And to prevent further reproach, I put my head back in the water, immersed sleek and smooth as a seal.

   Ewan's always been goal oriented, that's why he's so brilliant at his work. He can identify the end result, then fly directly to it, an archer aiming an arrow. It's all progress, all forward momentum. But I seem to have lost faith in the same goals. I'd be happy for time to be stopped completely or, if not, for evolution to be reversed. No more forcing myself to stand upright, no more guilt about being such an unwilling vertebrate: just revert to being a dolphin or whale, salmon or carp. A water anemone, even plankton would do. Regress to a sea creature and inhabit the joy of the ocean again - that submarine world where everything's aqueous, everything's one.

   They tried to fix me with sedatives, anti-depressants - Ewan tells me the pharmaceutical industry's the second largest after arms - but after a few false starts I refused to take any more. Drugs don't calm you. They claim you. They wrap you in a mosquito net till you can't get through the clinging white mesh to your own thoughts. You're neither on this planet nor entirely off: a permanent threshold to nowhere.

   Anyway, I don't need chemicals to soften things. The world has already lost its edges. It's like living inside a jigsaw that's all middle pieces: there are no walls, no sides to the room, no frame, no firm black lines keeping the world in place. Imagine inhabiting a watercolour that's constantly bleeding - everything spilling over and seeping into everything else - no skin around you, no fur, no membrane. That's how it is. Ewan calls it a kind of denial, a way of defending against a world whose edges are too hard, weapons too sharp, losses too jagged to endure.

   That's why I like being in the water. I feel safe here, a child in the softness of its mother's fluid body. Here, there's no difference, no separation. Everything's on the same canvas, painted by the same fearless brush, and the world is just one vein, pumping God's blood back into a heart that is eternal....

   Then suddenly hands are round my scalp and Ewan's yanking my head out of the water, panic etched on his face, convinced I was drowning myself by staying down too long. And behind him is the bird-featured guy who brought the coffee, but instead of collecting the empty cups, he's flapping one thin wing towards the TV while he drapes the other over Ewan's shoulder, all the time rotating him towards the screen as intently as if England were playing the World Cup.

   `Go for it,' I want to say, trying to catch the youth's eye. `I'd far rather Ewan was with a man. It's more liberating for him, and easier for me to cope with the jealousy.'

   But now, in the slowest of dream-like gestures, as though we are all under water, Ewan's hand is rising to cover his mouth and when I follow his eyes to the monitor, I realise the embrace between the two men has risen less from love than from catastrophe.

   I can't sustain the looking. Even the swiftest glance is heart-rending, searing straight through my softened skin. I turn my eyes away and stare into the bathwater. But the TV images are there too, inverted, and there is no escaping them: goliath structures of glass and concrete and steel, their burning, billowing flames and smoke turning the water deathly grey.

   Panicking, yet trying to stem the new sense of terror rising, I summon once more the memorised items from the painting, and thank God for art. What else will save us? Here they are again: the naked bodies, the roots and plants and sitting skeleton. Here too the tall white skyscraper, a fiery volcano engulfing its proud futility. Did Frida Kahlo see through time, then? When she lay in pain and painted her self-portrait, was she capturing this day too, when the most famous tower in the world would sink into flames? Did she foresee this moment, when the barriers between inner and outer would collapse and everyone would be staring helplessly into the same cracked mirror?

   Then the room service guy says something about a second tower crumbling and aren't those bodies falling, and I turn on both taps, hot and cold. The water crashes down into the bath till the faces and plants and shells start to tumble and blur. The level rises quickly and the guy makes for the taps to turn them off, but Ewan restrains him. He knows how to handle me, he says, we're very close, we're twins, and he comes over to coax me back, as he's always done, into some kind of semblance of normality. But I shake off his arm.

   `We need the water,' I insist, watching it pelt down into the bath and clamber out over the steep sides. `It's the only way to put out the fires.'

   Perhaps wanting to save our visitor from my dripping breasts and the black curls drowned between my legs, Ewan tries to drape a thick white towelling robe over me, but that too I shrug away. This is no time to be ashamed of nakedness. I'm relishing the water, the way it subsumes the TV images back into Frida Kahlo's painting, and I'm noticing with delight that my memory is more fallible than I'd assumed. There's an item in Frida's bath that I'd forgotten: an old-fashioned galleon, with a billowing vanilla sail.

   As it steers the waves and sails on through the rising sea - these waters which the burning towers have summoned, this flood needed to wash away the vanity and hatred of the world - I gratefully rotate the gold taps to full throttle. What is this small galleon but that original lonely boat summoned by the flood, the ark that seeks to rest once more upon the slopes of Ararat, so the dove may pluck the olive leaf of peace in its mouth and fly over the warring earth, till death is drowned by love and grieving and sorrow as if they'd never been?

   Meantime the two men are wrestling nearby, Ewan grasping the youth in his arms, bracing his fine head against those brittle white clad shoulders to prevent him coming near the taps, but I don't worry. This is a tug of war which will slip quickly from the intimacy of battle to that of love. For no one can stop it now, this water which has filled the bath and is spilling over on to the rug, seeping across the varnished floorboards and flowing out towards a disbelieving world.