In 1977, aged 26, Robyn Davidson made a 2700-kilometre solo camel trek through the Australian desert.
Her book about this journey, Tracks, became an international bestseller and has never been out of print. It established Davidson, who wrote it in the basement flat of Nobel Prize winner Doris Lessing's London home, as both a writer (she's a respected essayist and reviewer) and a wanderer.
Since then, she's divided her life between 40-odd addresses in Australia, London and India (the setting for another book, Desert Places, and until his death in 2011, the home of her long-term partner, Rajput aristocrat and politician Narendra Singh Bhati).
But now, she says, she's back in Australia for good. She's bought a house in Castlemaine, Victoria, where she can "practise Beethoven, and then go and dig in the garden like farmer Jane". When not digging, she's halfway through a memoir of her mother that's going "extremely badly", doing publicity for the movie adaptation of Tracks (out in April), and planning trips.
She may no longer have four camels and a dog in tow, but she's still in motion.
It has taken a long time for Tracks to make it to the big screen. The project has had many incarnations. "By the time Emile [Sherman, Tracks' producer] wanted it, I just assumed that, a) it would never get made, which was good, and so b), it didn't matter much who had it."
I confess that I found the movie a bit, well, unjoyful. "No, not a lot of joy," agrees Davidson without rancour. "But I like it, and like it more each time I see it. It's not the film I would have made - but then, it's not my film. On one level it has absolutely nothing to do with me or my life."
On another level, however, it feels accurate about both: perhaps Davidson herself was not the most joyful of people when she arrived in Alice Springs in 1975.
"I think that's true," says her friend, Rick Smolan, a photographer who met Davidson in Alice Springs, and helped her sell the story of her journey to National Geographic, where she first wrote about it.
"She was very fierce, very focused," he recalls. "She adored Diggity [her dog] and she adored the camels. I think she was more comfortable with animals than people."
Smolan felt enormous concern for her. "I was terrified she was going to die," he says. "Every time I left her, I would look at her in the rear-view mirror and think, ‘Is that the last view I'm ever going to have of her?"'
When Davidson reached the Indian Ocean with her camels all those years ago, the world press went wild. Who was she? Where had she come from? And most of all, why had she made this extraordinary six-month journey? Why, why, why? Davidson has always resisted this question, partly because she does not believe in the most obvious answer, that she did it because her mother took her own life when she was 46 years old.
It happened the year Davidson turned 12. Her family, driven off their Queensland property by drought and financial disaster, moved to Brisbane, and one day she came home to find her mother had used the cord of the electric kettle to hang herself from the rafters of the garage.
Davidson argued with the Tracks film-makers about using her mother's death as a motive for her journey. "The problem for me there," she explains, "is that the hidden message then becomes that for a woman to do anything extraordinary, she has to be disturbed in some way. She has to have something to work out."
Of course, her mother's death may have been part of a complexity of motivations for the trip - and, indeed, for her life.
"That is part of her," says Smolan. "There's a lot of people locked up there: the girl whose mother committed suicide, the girl who did the camel trip, and lots of others.
"What I do think," concedes Davidson, "is that having lost a parent, you know you can survive anything. There is a sense of being indestructible. For me, going to the desert was wonderful and large, but not weird. What I remember is entering into something exquisite. Something transcendently beautiful." She adds, "The desert gives you an awareness about where you actually fit in the world. You get this very clear sense of the way nature fits together, and your place in it."
This sounds a small thing, but really it's the biggest thing of all: an answer to the meaning of life. Davidson has spent much of her life trying to intellectualise this awareness, to pin it down, explain it, write about it. But ultimately, perhaps it's something that can only be experienced.
When she began writing Tracks, she did so with no journals, no notes, no record at all of her enormous journey. When Smolan heard this, he offered her his own notes and photographs, but she refused. And when he read the book, he says, it was perfect.
"She had remembered every pattern in the sand, every sunset, every moment like it was running in real time. I said, ‘How the hell did you do it?' And she said, ‘You were processing it and thinking about it and analysing it. But I was there."'