"I loved the book and wanted to use it in class, but reading it aloud didn't work. So I made up my own version and told that. And it was important to tell, not read, because that engaged me, forced me to get the stories into my head and find a way of acting them out - it forced me into being a storyteller."
Pullman reworked classics like the Iliad and the Odyssey for 12 years, three times a year - a wonderful apprenticeship for an aspiring children's writer. "Being spared the burden of invention, I could learn how the stories worked, and what my strengths and weaknesses were." His conclusion? "I can evoke atmospheres, give people pictures in their heads. And I can do the suspense thing, make people want to know what happens next. But I can't do funny stuff. When I try to tell a joke it falls flat."
Pullman gave up schoolteaching before he was 40 and lectured at Westminster College for most of the next decade, while studying Victorian novels like Bleak House, Vanity Fair and Middlemarch, and telling trainee teachers the stories of Aladdin or Cinderella. "It made me think about the essential ingredients of these stories, about their shapes, motifs, and so on." Pullman's latest project was born from this passionate belief that classic tales should be available to all children. In response to an idea Pullman mooted in a lecture, his publishers, Scholastic, have brought out 13 pounds 1 titles matching top children's writers to such canonical stories as Rumpelstiltskin (by Kit Wright), Aesop's Fables (Malorie Blackman) and Rapunzel (Jacqueline Wilson). Pullman himself has written Mossycoat, a variant on the Cinderella story.
It was an enduring fascination with Milton's Paradise Lost that inspired Pullman's most famous creation, the fantastical His Dark Materials trilogy, launched with the 1995 novel Northern Lights, and continued in autumn 1997 with The Subtle Knife (both Scholastic pounds 14.99 hbk/pounds 5.99 pbk). Pullman says he has "always carried fragments" of Milton's masterpiece with him, and before embarking on the trilogy he re-read it, along with Blake's poems and the Bible - in particular that part of Genesis detailing the Fall of Man. "I also read all kinds of commentaries on the Bible and Gnostic commentaries, but essentially it was Milton. I set out to do Paradise Lost for teenagers in three volumes."
Respectable critics have already compared him to Tolkein and Peake. The Washington Post called Northern Lights "the best juvenile fantasy novel of the past 20 years", and it won both the prestigious Carnegie Medal and the Guardian Children's Fiction Award. In its review of The Subtle Knife, the New Statesman rated Pullman alongside Lewis Carroll, E Nesbit and C S Lewis, as an author "who is so extraordinary that the imagination of generations is altered". Now published in 18 languages, both books are world-wide bestsellers; Northern Lights sold 10,000 hardback copies in the UK, and more than 80,000 in paperback, while The Subtle Knife sold 20,000 copies in hardback (and as many in America) and has been on the bestseller lists since being paperbacked in September.
Does he still have that 12- to 13-year-old audience in mind when writing? "No. Of course, a young audience doesn't know quite as much about the way the world works as adults do. But I don't compromise with difficult language, complex ideas, powerful emotions, or whatever. I just hit the story as hard as I can while trying to remember that one or two things might need a bit of explanation."
Pullman's didactic taste for pushing young readers rather than pandering to them can have explosive results. My 10-year-old daughter devours most children's books but was reluctant to read Northern Lights, claiming it was "too difficult". She struggled with the new words, complex phrases, and unpredictability of Pullman's imagination. Yet after taking turns to read aloud in order to get her past page 50, she was hooked, finishing the next 350 pages in a day, and polishing off the sequel in another three - without help.
Pullman's multi-faceted universe is populated by angels, demons, witches, ghosts and spirits, and mysterious child abductors. Northern Lights tells the tale of 12-year-old Lyra Belacqua who lives in a mythicised 29th-century "Brytain" and has an animal familiar or "daemon", with whom she sets out to discover the nature of a spiritual particle called Dust. The Subtle Knife starts in a world like our own with another youngster, Will Parry, whose own quest is to find his long-lost father. The two meet up and discover the subtle knife, a blade that can cut anything - even windows on to other dimensions. Meanwhile the reader begins to suspect that Lyra's father, the menacing Lord Asriel, is planning nothing less than an all-out attack on ... God.
This concern with the supernatural and mysticism ("I would call it wonder," he says) stems from Pullman's own philosophy about the nature of mind and matter, the existence of God, and the place of morality in human affairs. These "big themes" are the very stuff of young minds, and a so-called children's book is the perfect place to explore them.
"Children and teenagers ponder these questions a great deal: 'Who made the world? Is there a God? Why am I here? What's life about?' We think most passionately and urgently about these questions in our teens. After that, other questions supervene: 'Does my bum look big in this? Will Arsenal win the Cup? Can I pay this bill?' And so on."
Though he is not interested in convincing others, Pullman's convictions clearly inform and shape his work. Like Blake, he believes: "there is no soul separate from the body ... everything we call soul is perfectly explicable, understandable, or celebratory, in terms of matter."
Once you adopt this position, he continues, it is only a small dialectic step to regarding the Christian deity as perverse: "God is either responsible for this world, or he's not. If he is, then he's responsible for plagues, tapeworms, earthquakes, all kinds of hideous things. In which case he's wicked, not worth worshipping. So why do we worship Him? The whole answer to this is being worked out in volume three."
Since 1 January this year Pullman has been working on the as-yet-untitled final instalment, scheduled for publication in September 1999. His office at his Oxford home is a shed at the bottom of the garden, where he writes three pages every day - always in longhand on the same A4 narrow feint pads, in fine-point ballpoint pen - averaging around 1,100 words, though "it depends how much dialogue I put in". He always writes the next day's first sentence before finishing, to avoid starting with a blank page.
Pullman always writes in the third person. "I function like a camera in a sense. I've thought a lot about this, and the way that in cinema the camera functions as a narrator." Having already sold the film rights to the Dark Materials trilogy, Pullman has no worries about possible maltreatment of his oeuvre by Hollywood; the only thing a writer can do, he says, is demand as much money as possible, then forget the whole thing.
"There's nothing ignoble about wanting to pay the bills. I do this for money, as well as the other motives, which I wouldn't want to rank in order of nobility, frankly. Earning money is as important as craving immortal fame, which is as important as the psychological need to write every day, which is as important as the wish to create something out of the intangible material of language ..."
But isn't there also, I ask, some deep-rooted need to touch something in children, to put them in contact with a certain way of being, or thinking, or experiencing the world? Something spiritual, even?
Pullman looks me in the eye, allows a pause for effect, and with the merest hint of a smile, says, "To teach, you mean?"