BOOKS / Classic Thoughts: A joy stripped naked: Natasha Walter on Vladimir Nabokov's late great novel, Ada, which was published 25 years ago this month

EVERY WRITER is a slightly different beast to each of his or her readers, but many of Nabokov's critics seem to dress him up in a wolf's suit that makes him quite different from the lamb that I know. And nowhere is that more true than with Ada, his last major work. A fantasy novel full of wit and artifice, it was seen by one critic as 'a political allegory offset by linguistic legerdemain'. But what can be taken for a clever folly rides on its supreme simplicity: it is no more and no less than the greatest love story ever told.

One clue to Ada lies in Lolita. 'Did she have a precursor?' Humbert asks of Lolita. 'She did, indeed she did. In point of fact, there might have been no Lolita at all had I not loved, one summer, a certain initial girl-child. In a princedom by the sea.' When Humbert was 13, he goes on to explain, he met a 12-year-old girl called Annabel: 'All at once we were madly, clumsily, shamelessly, agonizingly in love with each other . . .' With each other, we note. Humbert's tragic attempts on Lolita's freedom stem from his need to recreate a shared and human joy.

In Ada, that ideal of a total, intellectual and sexual love between precocious children is given a second chance. The 14- year-old Van meets his cousin Ada, in another princedom. The young Humbert and Annabel shared an interest in 'the plurality of inhabited worlds' and here that interest is made real. We are not on Earth, where lovers turn to abusers. We are on Antiterra, where one can occasionally realise 'the happy-forever feeling at the end of never-ending fairy tales.' The story of Van and Ada is not without its own lancing infidelities and taboos, but in their mutual love we are allowed to see the perfect nugget of joy at the heart of Nabokov's world.

Perhaps we are led to thinking that Ada must be less 'important' than Lolita, less meaningful, and necessarily some kind of skit or folly, because of its lack of standard novelistic realism. But what kind of realism did Nabokov intend Lolita to offer? A stagey one at best: 'Considerations of depth and perspective (a suburban lawn, a mountain meadow) led me to build a number of North American sets.'

Freed from illusionist sets, in Ada Nabokov wanders the tumultuous literary and aesthetic landscapes of his own soul. The novel opens with a twisted quotation from Tolstoy; conversations slip easily into chunks of Chekhov; the house where they love and part, Ardis Hall, is a misty recreation of a Turgenev country seat set plumb in the middle of America. This is a world where Van can fight a duel in a pine forest, 'in the kind of single combat described by most Russian novelists and by practically all Russian novelists of gentle birth,' before speeding off to a penthouse in Manhattan.

Van and Ada are surrounded by the kind of delicious dazzle that goes against the grain of contemporary fiction. Pool-side patios, luxury liners and glossy furs are their natural accessories. But rather than springing from a cold, Scott Fitzgeraldish self-consciousness about taste, this upfront glamour is part of the unbuttoned generosity Nabokov shows to his charmed couple. These children of his dreams are so close to him, with every birthmark and mannerism and trick of speech pulled from an deep inward shock of creation, that they become closer to us than our own childhood. And because he is so without irony in their characterisation, what lies at the heart of this skittish maze is a joy stripped naked.

Nowhere else does Nabokov dare to give us that. Nowhere else do we approach so close to the soft core of love that lies at the heart of his work. The same love that once twisted and failed, and drove Humbert to lose his soul and destroy Lolita's life, is here an absolutely convincing reality: 'Reality, better say, lost the quotes it wore like claws - in a world where independent and original minds must cling to things or pull things apart in order to ward off madness or death . . . For one spasm or two, he was safe. The new naked reality needed no tentacle or anchor; it lasted a moment, but could be repeated as often as he and she were physically able to make love.'