First, an autobiography, written in the mid-1990s. A comic book about a man struggling to become a writer, who is also a man struggling financially to survive. "I wanted to write an essay about money. I thought I'd call it Essay on Want." And then a fiction, his new book, Timbuktu - what he calls "a little book", a story narrated by Mr Bones, a mongrel dog, the companion of Willy G. Christmas, an erstwhile poet and a tramp. So many tramps and vagabonds in Auster's work. But then, what is a tramp if it isn't the writer's alter ego? The mirror image of the writer, quite literally a non-entity, a missing person - as the novelist is the missing person in his own fiction? The story begins on the corner of a street in Baltimore. Lots of corners, too, in his work - a vantage point, a choice of paths. He originally thought that Mr Bones and Willy were going to be just minor characters in some much bigger book. But that's what happens, he says. One thing keeps leading to another. Something minor turns out to be something major. "You take a turning, you begin to think it's the wrong turning, you get lost, you're out there in the rain. And then, suddenly, there's that little inn you've been longing for all your life."
Paris looked like a wrong turning. Three years there living, as he says, in utter penury. Trying to write poems and literary essays. Having to put up with degrading, humiliating involvements simply to earn a crust. Back in New York, he earned money through translations, "cranking it out". He invented a card game; he called it Action Baseball. "Just like real baseball," he'd tell the card manufacturer's reps as he tried to flog the game at toy fairs. He wrote a novel, a detective thriller called Squeeze Play, in which an apparent murder turns out to be a suicide. "I just did it to make money, that's all. It's not a legitimate book." Both card game and novel are included as appendages in his autobiography - what he calls "evidence". His son had been born, in 1977, but a year later his marriage was on the rocks, everything seemed to be cracking apart. "I'd spent the best part of a decade in total poverty, working very hard to produce work that I'm not unproud of. To end up with zero."
It was 1979. He was alone, he was writing little. He felt he was falling, "that the ground was opening up, that the things you clung to before were no longer there." Then something happened. Some mystery, some miracle, the night before his father died. He had been out to the theatre with friends, to see the work of a performance artist that he admired. Getting home, he couldn't sleep. He sat down to try and write for the first time in a while, and he produced the prose poem White Spaces, a reflection on the gruelling reality of trying to write, trying to find a voice. The next morning, the phone rang with the news that his father was dead.
It was not his father's death that made him a writer - that moment had come the night before. But the money that his father left him enabled him to write. "It was not a great deal, but it was enough." For the first time in his life, he could afford to do nothing else. And the first thing he wrote was a reflection on his father, The Invisible Man, and an autobiographical fragment, written in the third person, called The Book of Memory.
Five years later came The New York Trilogy, the book that made his name in the world. Each story is a quest for a missing person. "The idea at the end is that the questions have been resolved in that the character realises that they never can be resolved." At this point, Paul Auster becomes completely identified with the image he has of the writer. He has placed himself out of this world, has made himself a character in his own fiction. His next step, the next turning, had to be how to get back in. "To be both in and out of the world." It wasn't until the 1990s that what had been a heroic, self-lacerating project suddenly and unpredictably changed. He came out of his room, out of the book, and into the world of film. The emergence came, of course, through fiction, as ever his point of entry into the world.
In November 1990, the New York Times rang to ask if he would be prepared to write a short Christmas story for the paper. It was the first time that newspaper had published a work of fiction, and Auster, thinking it funny - a story in a paper of record - immediately said yes. Days before his deadline, he still had no story. "I was about to ring and say I can't do it. I was staring at this little tin of Dutch cigars that I smoke, and suddenly I began to think about the man who sold them to me. How, in a big city like New York, you have these relationships with people - you can't call them friends, you don't know them - and yet they are cordial relationships, part of the texture of everyday life. Something that makes life much more pleasant." The story he wrote, Auggie Wren's Christmas Story, became the film Smoke, directed by Wayne Wang, in which Harvey Keitel plays Auggie and William Hurt plays the writer Paul Benjamin. "Paul, because I wanted to write it like a news story, as though it were true." And Benjamin because that's his middle name. It is a story about giving and taking - Auggie gives Benjamin his story - about lying and stealing. About arbitrary kindnesses between people. And about the point at which fact and fiction merge. The last scene has Keitel, smiling his Cheshire-cat smile, assuring Hurt that every word of his urban fable is true. "Bullshit," replies Hurt - the last word of the film.
After 25 years in his room, the film was "eye-opening", he says. "A big revelation. It reminded me that working with other people is fun. It gave me back memories of playing sport as a kid, of playing in teams, of everyone doing his or her best." It also gave him money. I asked him when he first started to earn his living solely from his writing. The answer is shocking. "Things got a bit easier in the 1980s. I was also teaching at Princeton. But it was only in 1991 that I looked at what I was earning and realised we could get by."
Timbuktu is a novel of reconciliation. Auster calls it "a love story", told by a dog "who is and isn't a dog". The book walks a tightrope between what is plausible and what is not. Clearly, dogs do not talk, but even if they did it is moot that they would talk in the philosophic manner of Mr Bones. What matters, Auster says, is the emotions. "And because he is a dog, it became possible to express very pure, intense emotions that we all feel." This is a love story without irony. After Willy's ignominious death on a street corner, Mr Bones cannot endure life without him.
What's odd about this is that, in many ways, his material life is improved by Willy's death. He is taken in by a family and treated, on the whole, well by them. You could say he lands on his feet. On the final page of the book, Mr Bones decides to play an old dogs' game. It's called dodge-the-car. It's the road to oblivion.
Timbuktu is an expression that commonly signifies the limit of the world, Auster explains. "People say I've been to Timbuktu and back, when half the time all they mean is that they've been on a shopping trip to Manhattan." Willy G Christmas turns this figure of speech into an image of the afterlife, which Mr Bones, in his dog-ignorance, takes for real. He is going to join Willy in Timbuktu.
A bit shame-faced, I tell Auster that I once made the same mistake as Mr Bones. I'd followed a road in the desert, signposted to Timbuktu, for miles before I realised that it was going nowhere. That it didn't exist. It was just a joke. That's funny, he said. "That's very funny." Funny, because, for once, the imagination triumphs over reality. Even if Timbuktu exists, which it does, he says, it's an oasis in the desert somewhere in Africa.
Still, it exists more as an idea than as a place. In the world, our world, Timbuktu is fiction. And, as Auster might say, all the more real for that.
Timbuktu is published by Faber, £12.99 in UK