NEXT THURSDAY SOTHEBY'S WILL auction a manuscript of 160 pages called The Tales of Beedle the Bard. The catalogue copy says “Property of J.K. Rowling, handwritten and extensively illustrated by the author”. The estimate is £30,000 to £50,000.

It is the last item in the usual Christmas sale of books and manuscripts, including children's books. There is a very nice 1924 edition of The House at Pooh Corner, signed and on offer for £2,000 to £3,000. For older readers, there is a complete set of the James Bond novels, estimate £15,000 to £20,000, or you could have the other James, Mr Joyce, and a lovely, though unsigned, 1922 edition of Ulysses, printed by Sylvia Beach at Shakespeare and Company in Paris; estimate £9,000 to £12,000.

But the prize of the sale is clearly the Rowling, which is being treated like an illuminated manuscript and locked in a glass cabinet. The book is leather-bound Italian paper, and hand-tooled with silver and moonstones. The new owner will be purchasing the object, but not the copyright, so none of the stories inside can be printed or reproduced.

That this is all in a very good cause, no one can doubt — the proceeds of the sale will go to the charity The Children's Voice, of which Rowling is a founder. The charity works on behalf of children in institutions, particularly in Eastern Europe.

As a child who started life in an adoption centre myself, I know that however difficult or inadequate families may be, they are always better than anything state care can offer. Perhaps J.K.R can work her magic on the British Government, too. A few Hogwarts-style solutions would save a lot of money and a lot of misery; it costs an average of £100,000 a year to keep a child in care in Britain. For £25,000 you could board them at Eton or Charterhouse, and I could have some of them in the holidays.

There must be others like me who could commit to school holidays and be on call. Not only would we save money, we could teach the kids to read properly which, as we are discovering, has not been happening under new Labour's educational priorities.

As a writer, I'd like to think that there are kids now who will read my books later. If reading has been sold to them as difficult or boring, what happens to literature?

I was always impressed that Harry Potter had waved his wand over kids who were illiterate sloths and turned them into bookworms. Unfortunately, the Potter effect has not spread beyond the walls of Hogwarts, as we all hoped it would. But why would it? Kids love enclosed worlds — it's why computer games are so successful. Hogwarts is an enclosed world in a way that Philip Pullman's His Dark Materials is not. The Hobbit and The Lord of the Rings are enclosed worlds, Finn Family Moomintroll is not; not least because its adventures always depend on some strange and unexpected destabilisation from outside its borders — the arrival of the Hobgoblin's hat, or the mysterious boat, or a comet.

Fantasy literature tends towards the enclosed, and most computer games are based on fantasy. Literature — just literature, no labels, no genres — tends towards border crossings, trespass, maps that go off the page. This is obvious in something such as David Mitchell's Cloud Atlas, but equally true for Dickens, where the satisfactions of the story can lead us to believe that we are in an enclosed world, when in fact that world is self-exploding. In Beckett, the suffocatingly simple world of Waiting for Godot or Happy Days becomes a bewildering open labyrinth. Early criticism of Beckett complained that he had destroyed the well-made play. What his critics really meant is that he had upset our love of enclosed space.

I like garden squares and tiny tea-rooms. I like being held, and knowing that my own little world is safe. But I know, too, that the excitement and challenge of literature is to go beyond all of that into a place that is often uncomfortable. I can't expand my mind or my emotional range if I always choose an enclosed world. Don't mistake me — James Bond is an enclosed world, Jane Austen is not.

Of course, long familiarity with anything makes it safe again — which is why even the most radical art becomes commonplace, and why we must always be making things new.

Children need the safety of enclosed worlds, but they also need to be shown the remarkable emotional and imaginative landscapes that lie outside.

The Tales of Beedle the Bard and other items in the sale will be on display from tomorrow to Wednesday at Sotheby's, 34-35 New Bond Street, London W1.

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