IT WAS A meeting worth waiting for. Our greatest botanical writer, a man of quivering sensibility and encyclopedic knowledge – and perhaps the most spectacular and imaginative abstraction of the plant world on Earth. Richard Mabey meets the Eden Project. The only surprise is that it took so long.

Over the course of “three seasonal visits” to Cornwall, staying in a local B&B, Mabey wanders around the Project’s site and its signature zone. He sits in the Warm Temperate Biome, pushes into the hothouse world of the Humid Tropical Biome. He breathes in the scents, examines buds, peers at blooms. In short, he does what he does best. He lolls, slowing his pace to a Zen-like amble to observe, reflect and revel in the manifold marvels of the natural world.

What would have been little more than a feature article for a lesser writer becomes an entire book. His visits spin off into long, effortless meditations on such subjects as the bloody and destructive sugar trade, the history of cork and hemp and olive production, Victorian orchidomania, the pollination of Amazonian epiphytes, and the strange redundancy of the human olfactory sense. In doing so, he is fulfilling one of the Eden Project’s stated, high-minded aims: to disseminate botanical knowledge, to encourage a reflection on the part plants play in our lives.

In one sense, Fencing Paradise is a critical review of the Eden Project. He is clearly impressed – as most visitors are – by the sheer scale of it, by its vision. In its use of artworks and theatre, Eden is an immensely stimulating place. It is, he feels, “the opposite of didactic. It’s provocative, questioning, curious.” By spending a long time there – longer than the public – he notes the onset of a “fond and deeply irrational attachment” to certain spots.

Mabey’s reservations about the Project are more fundamental. They go to the core of our own troubled relationship with the natural world. Just as the original myth of Eden hinges on the idea of banishment, so its latter-day incarnation in a disused Cornish clay-pit illustrates our distance from – and dominion over – other living things. The language he uses is revealing. Eden is variously “a shrine … a theatre of ecology … an immense construction in organic Lego”. He compares it to the feel-good agenda of the 1992 Rio Conference, the contradiction-in-terms notion of ‘sustainable development’, which itself helped inspire Eden. Above all, the Project “reinforces the image of the world as humanity’s garden, contained and nurtured for our benefit.”

There is an oft-cited story about the enthusiasm of some inner-city children for Eden. But what impressed them was not the plants or the eco-message behind them but how the whole idea came into being, how it ‘happened’. Businesspeople likewise are very taken with the ‘can-do’ philosophy of Eden and its dynamic creator Tim Smit. Visitor figures have been in decline from the highs of the first years, and the nagging suspicion remains that it is a triumph of style over substance.

That said, there is also a sense at Eden that it was never intended as anything more than a vast enabler, an experiment, a performance. Like some good, rank, nitrogen-rich compost, it has been scattered over the ground to see what will spring up. Uneasy as one feels about the artifice of it, something in Eden’s spirit makes you grateful that it exists.

Mabey sees that “slowly, inexorably, places like Eden are becoming the planet”. The last patches of wilderness are shrinking, nature is packaged for our consumption. From an ecological perspective, this seriously reduces the essential power of biodiversity. Intentional or not, this is perhaps Eden’s most important message.

Ejected from the Garden of Eden, we became agriculturalists, burning forests, fencing off fields, shaping the world to our own requirements. The pre-Fall Eden became a memory of innocence and forbidden perfection. Now, the Eden Project brings us full circle. The Garden has come indoors, recreated, sustained with climate control, laid out with visitor paths, the entire ageless range of botany reduced to a few hothouse plants. It is as much a warning as a celebration.

In this wonderfully thoughtful book Mabey concludes with his own “fantasy for Eden”. He would add a Wild Biome to its inventory, an area of the clay-pit where the ground would be simply left. It would be labelled and waymarked – but that is all. The development of the flora would be a constantly evolving exhibit.

As if by way of endorsement, the most lucid image I take from his book is not from Eden at all. Mabey is walking from his B&B towards the site. It is May. The Cornish wall-like hedgerows are bursting with new life. At that time they are, muses Mabey, “the most beautiful things in England”. He reaches into a tiny cleft between the stones, amidst the lady ferns and wood sorrel, and pulls out a “crumbling wad of dead moss, a curled-up millipede, flecks of stone and a smidgen of mould.” Muddy-fingered moments like that are worth more than a lifetime in the biomes, and they’re free.

Philip Marsden’s latest book is The Chains of Heaven: An Ethiopian Romance. He lives in Cornwall.