"My God," I breathed, looking around me in wonderment. Down, down, about a hundred and fifty yards or so long and fifty wide, swept the huge avenue, falling dramatically, perhaps as much as twenty feet, inducing in me the sense that I was being pulled inexorably into the centre of this amazing building. Above us space, so much space, an incredible, living expanse, a vibrant, thrumming immensity.

"Awesome."

It was here that Louise Bourgeois's giant spider had sat for the first year of Tate Modern's existence, an enormous metal sculpture with stairs to an upper balcony, which the viewer could walk around, reinterpreting the notion of allowing the audience to engage with the art. It had recently been replaced by Juan Muñoz's eery grey sculptures, and Simone and I skipped down to look at them.

They are an extraordinary spectacle, an intriguing use of the epic space of the Turbine Hall. The whole installation is divided into two parts and can be observed on three levels. From below, where we were initially, it is a gloomy, slightly edgy expanse of space, mostly dark but with shafts of light falling from an upper level. Two empty elevators ascend and descend in a constant, but uncertain rhythm. As you walk beneath it, looking upwards, out of the gloom a series of grey sculptures, in a variety of poses, can be seen. What are they doing? What are they thinking? They are enigmatic, detached, involved in their own personal existence, their own private drama. On the upper level of the gallery the scene is transformed into something lighter. It appears that there are a number of shafts, which one presumes to be the tops of the ones which have just been observed below; some of them, however, are illusions, painted on the surface. And the third level can be seen from above, from the walkways running alongside the permanent galleries: from the windows one can look down on the patterned floor, spotting which are the illusory shafts and which the real, and, within the real ones, glimpse once more the vague, curious figures of the grey sculptures. Eery, curious and engaging.

Once we had finished looking at Muñoz, we purchased tickets for the Arte Povera exhibition and took the escalators to the fourth floor. "What can you tell me about this, then?" asked Simone.

"Hmm, not that much actually. I'd never heard of Arte Povera until a few weeks ago. I was in the Pompidou in Paris..."

"You were in Paris?"

"Yeah, for the weekend."

"I'd love to go there. Never been."

"I'll take you sometime," I said casually. I wish, I thought.

Simone laughed. "I'll hold you to that. So anyway, you were in Paris?"

"Yeah, and in the Pompidou Centre there was this amazing installation. It took my breath away. It was by an artist called Guiseppe Penone. Basically, it consisted of a room full of laurel leaves, thousands and thousands of them, covering the walls, ten, fifteen thick, held in place by chicken wire. The smell was fantastic. So fresh, so clean. Really beautiful. It was such a wonderful experience, a world of calm. I adored it. I stood in there for, God knows how long, minutes, an hour, I don't know. It was one of those moments, you know, when you can feel all the stresses coming out of your body, when you can feel yourself relaxing, coming down..."

"Chilling out."

"Yeah, just so. When I got back I did some internet searches on him and found a bit of background information. Then I found out he was part of the Arte Povera movement from Italy in the sixties and seventies, and by extraordinary coincidence, there was this exhibition on here. So I don't really know what to expect."

"Cool. So is it all going to be, like, installations, and rooms full of leaves?"

"Don't know. Arte povera means poor art, apparently. They were very experimental, at a time when pickling sharks or cutting cows in two or displaying an unmade bed would have been considered certifiable rather than just tediously arty. They used ordinary materials - dirt, trees and stuff - which was "poor", or ordinary, everyday sort of stuff. But what they wanted to do was get rid of the notion of the artist as genius - the tortured van Gogh idea - and look at the art itself, without boundaries, without restraints. The essential thing, I think, is the link between the art and life itself." I stopped, realising I was descending into meaningless waffle.

"Wow," said Simone. "There won't be any Green Ladies then?"

"No," I laughed. "Nor puppies with sad eyes, or Constable's Haywain, or van Gogh's insanity."

"Oh well, it can't be that bad, then. Though I quite like van Gogh. Is this it?"

We had arrived at the entrance to the gallery; I handed over the tickets and ushered Simone through. My heart sank. The first few exhibits were everything you would expect in a pastiche of a modern art gallery: a few pieces of metal wire moulded into interesting shapes, some scraps of cloth hanging on a wall, an empty box. Visions of Tony Hancock in The Rebel floated through my head. After the build up I had given it - the link between art and life and so on - we were going to be treated to a collection of junk dressed up as art: Tracey Emin with an Italian accent.

Simone, bless her, tried to be enthusiastic, attempting to draw meaning from the seemingly meaningless. I put a brave face on it and joined in, but I was aghast. Please, God, don't let it all be like this, I thought.

And lo, my prayers were answered. The exhibition came to life in the third room, where a painting by Michelangelo Pistoletto was hanging. Called Three Girls on a Balcony, it was an extraordinary work, in that we, the viewers, were an integral part of it. It was a mirror painting, featuring three women leaning on a balcony looking outward. The rest of the painting was a mirror, so it appeared that it was we, the viewers, whom the three women were looking at. As Simone and I stood before it, we were drawn into the painting itself, unwitting participants in a timeless drama, the focus of attention for these three, nameless Italian women.

"This is cool," said Simone, posturing before the painting, observing herself in it. We laughed at our reflections. Simone grabbed me by the waist and pulled me towards her, so that we were in an embrace before the watchful trio. Ah, but what did they see? As we embraced before our two-dimensional audience, I wondered: what are we? Two lovers, conscious only of themselves and oblivious of the world? Or two friends, close, happy and trusting? Or even, let's face it, it's physically possible, mother and daughter? What did people see? How did the world perceive us? How did the painting perceive us? Watching the neutral reflections of our bodies as they integrated with the exhibit, shimmering, changing, moving, I gloried in Simone's touch, revelled in the feel of her silky soft skin, but the questions rampaged through my mind. What were we? And what did people think we were? What did I see, and what did they see?

"We look like a pair of good-time girls, under the disapproving eye of the locals," Simone laughed, affecting a jaunty pose. "Look at them, they're just jealous." She raised her head coquettishly and flicked the back of her hair, shaking her head as she did. Such youth, such confidence. I wasn't sure on which side I belonged: with Simone and the good-time girls, or the reproving women on the balcony. Perhaps, soon enough, I would find out. For now, I was content merely to be with Simone, to feel her arm around my waist, the thrilling touch of my hand on her bared hip, the whisper of her breath on my neck.

The exhibition improved dramatically after the mirror painting interlude. The next gallery, a huge, extended room with an amazing variety of exhibits, was riveting. What really struck me about arte povera, what attracted me to it, was the simplicity of its composition. Through saying, or showing, very little, it inferred sometimes enormously significant meaning: the seemingly inconsequential - a shoe, perhaps, or a tobacco leaf - assumed greater importance through being placed in its artistic context, its underlying meaning revealing itself, the connectedness of objects, of events, of moments, becoming clearer. Arte povera allowed us to see the layers of meaning in any given object; life was revealed as the multi-faceted, joyous celebration we know it to be. Through artistic minimalism came intellectual inquisitiveness: a chance to understand.

It was art without preconceptions and free of philosophical or theoretical baggage. It gloried in experimentation and revelled in new materials - earth, industrial by-products, mounds of tea leaves, household rubbish and living things; and not only physical objects - moisture, air, sound and energy were harnessed, too, in the mission to explain. Giovanni Anselmo, for example, created works like 'Eating Structure', which combined animate and inanimate objects to create living, breathing sculptures which possessed natural functions.

"Look at that," I snorted derisively to Simone when I first saw it. It did, indeed, look ridiculous, a caricature of pretentious modern art, comprising a clump of lettuce leaves stuck between one large block of granite and another, smaller block, with a band of metal clamping the two blocks together.

"Well," she replied, sharing my amusement, "it's not every day you see a head of lettuce exhibited in an art gallery. Flower show, maybe, but not an art gallery 3;"

We crossed the room to inspect it and, despite ourselves, our cynicism was stripped away as we read the explanatory text. If the lettuce was allowed to dehydrate it would wither, the metal band would lose tension and the smaller of the granite blocks would fall off. The sculpture had to be constantly fed with new lettuces in order to exist.

"Actually, I see his point," Simone said, inspecting it closely. "Feed the need. The story of life."

"Cause and effect. The natural flow. Things happen. People fall in love, for example," I averred, "and that love has to be nourished or it dies."

"'Withers and dies' 3;" We laughed at the quote from Richard Thompson. It was a song we both knew and liked, a sad song of disconnected emotion. "It's quite true, though," Simone continued. "'My dreams have withered and died'; through lack of nourishment the lettuce withers and dies, and the force which helped bind the blocks together dissipates. The bond is lost 3;"

"And so the moral is: feed your dreams," I concluded. And just give me the chance, I thought to myself, just give me the chance.

We rounded the corner and came upon the section I was most interested in, the artist who had first alerted me to arte povera, Guiseppe Penone. I had seen pictures of some of the works in this exhibition, but I had not grasped quite what they were, and I was unprepared for the beauty of the objects or the feelings they would awake within me. They were tree sculptures of the most profound beauty, objects as piercingly perfect as I've ever known.

And it was Simone who explained them to me. The definition of beauty from the epitome of beauty.

There were three of them in the exhibition, though I believe Penone has created more. They were living sculptures, trees which had been pared down to reveal their essence.

"They're stunning," sighed Simone, cricking her neck and staring closely at the curious objects. They were each about twenty feet long, beams of timber which had seemingly been chiselled, with spindles and spikes emerging from a central core at random points and in random directions. "He's cut away all the dead wood, revealing the living tree, with just the knots showing," she explained.

All of a sudden, the piece made sense to me, and before my eyes it transformed from a lump of wood into an object of unimaginable beauty. Following the irregular growth rings, he had stripped away all the extraneous wood from around the knots until he arrived at the the young, living, growing core of the tree. There, delicate and lovely, in the middle of the wood was a spindly, fluid, living object: there was the shape that the tree had been at a certain point in its existence, when it was still a fresh, young sapling.

"Extraordinary," I replied. I had such a strong temptation to touch it, stroke it, caress that beautiful wood, feel the buzz of life within it. It was so beautiful I felt like crying.

"It's turning man-made objects back into natural, living things."

"Showing that seemingly dead objects have life still inside them."

"And each being has, buried within it, the core of its past experience. For all eternity."

Unconsciously, I found myself holding Simone's hand as we gazed in wonderment at this exceptional thing, trying to understand it, trying to fathom its depths of meaning. Within us all is the kernel of beauty, the moment of our genesis. Where does time start, what is the physical moment of birth? And can that moment, years later, through the ravages of time, the sterile advance of experience, be reclaimed? Is that core waiting, hiding, lurking, hoping one day to be re-discovered?

I stared into Simone's eyes. She looked so beautiful, alert and bright, face beaming with curiosity and wonderment. I felt as though I could see her soul, felt that I could connect with the beauty inside her. Momentarily, I was overwhelmed with longing for her, a pining to love her, cherish her, adore her every movement. The beauty of nature and the beauty of art had come together, inseparable, bound to one another by the innate perfection of each. I almost shouted "I love you" to her, but somehow restrained myself. Too soon, I knew, too soon.

But sometime, somewhere, I had to share my feelings. Simone was in my mind, my dreams, my body, my heart. Every waking moment, every dreaming second, at work, at leisure, conscious and unconscious, she inhabited my very soul. I needed Simone Clements.

This story is dedicated to Juan Muñoz, who died in August 2001, at the shockingly young age of 48. A beautiful man.

On to next story: Simone's Diary, July 5th