IT BEGINS with poetry, this story, the story about how Ben Okri became a writer. Stories are important, as we will see. And this one begins as follows: one rainy day in Lagos, a 14-year-old boy sat down and wrote a poem.
It was, Okri says, "a revelatory moment". He had been intent on becoming a scientist. Now he began to "incline towards literature". As he grew, there were more poems, journalism, short stories, a move to England with the seeds of an unpublished novel. Later, there was the Booker Prize, a slew of other prizes, an OBE. But I'm getting ahead of the story.
Stories are crucial, Okri will tell you. His formation as a writer is steeped both in the classics of European literature and in the oral tradition of his Nigerian family. When he tells a story, he sits back and lets it unfold, his voice warms to it, he lets it take its own time.
Of course, he says, the events of that rainy day didn't happen all by themselves. He was reading at school, though literature was "in the corner of my field of vision". He found himself "mysteriously stirred by words, by ideas and visions". "The Rime of the Ancient Mariner had a formative effect on me. I think it's one of those works that if you encounter it very early you're doubly enchanted by the beauty of the language and the strangeness of the vision. It stays with you."
Then, having been turned down for a place at university to study physics – at 14, he was too young – there were months of killing time in the house in Lagos, exploring his lawyer father's library. First the philosophers, the classics, then Dickens, Shakespeare, Robert Burns, Walt Whitman. "It was almost like discovering a homeland. I was just lost in the enchantment of words."
He was writing, he says, before he knew it. "You didn't call it writing because you didn't think that writing was something that living people did. It was something that the great dead did." That rainy day, though, was different. "I made a certain decision, I thought: 'OK, you have to stop messing around, Ben Okri, and decide what you're going to do with your life'.
"I took a piece of paper and drew what was on the mantelpiece. I spent a lot of time doing that. And then I took another piece of paper and wrote a poem. And when I finished these two activities, I looked at the drawing and it wasn't that good despite all the time I'd spent, and I read the poem, and it wasn't that bad.
"But it wasn't so much how good or how bad the poem was that decided it for me, it was how I felt when I was writing the poem. It was as if I, Ben Okri, disappeared. It was that self-forgetfulness in the writing of poetry, I still have it to this day. When I write a poem I go into a state of self-forgetfulness and something higher takes over, I like to call it my best self."
Now, sitting in a room at his agent's office in London, drinking Earl Grey tea and eating biscuits ("Which biscuits are these? Digestives! I love Digestives!") he tells me he is writing poetry again. His first collection was published in 1992, the year after he won the Booker Prize for The Famished Road. His second, Mental Fight, was an extended sequence of poems for the Millennium. After 11 years, his third is imminent.
"I'm conscious of a series of circles working its way through my life. And at this particular moment I have come round to the beginning of my writing cycle. It begins with poetry. There's hardly a day that goes past on which I don't write poetry. It's my most natural dialogue with life. If I want to make sense of something that can't be made sense of, I go to poetry first.
"This is the first time for more than 20 years that I have been able to devote myself only to writing and working on the poems. It's a costly decision because poetry is not going to pay your bills, so you do it purely from love, purely because this is what makes you happiest, what takes you back to your roots. It's a revitalising, re-energising thing."
Okri chooses his words carefully, fluently. He has garnered something of a reputation for speaking of literature in grandiloquent terms, which has led to some literary sniping. Critics have been divided about his work since The Famished Road, which some consider more abstract and more whimsical. But I must return to the story, for stories help us to understand.
After that rainy day in Lagos, Okri took his writing more seriously. He began to study literature and write pieces of campaigning journalism about the poverty and injustice he witnessed in his homeland. When publishers had had enough of these, he rewrote some as short stories, and watched in surprise as the characters took on a life of their own.
"This is the nature of the imagination – the minute I began to tell them as stories, the stories ran away from the facts. The injustice faded into the background, and was not the primary theme but was one theme amongst many. I think that saved me from being too didactic. Literature must persuade first of all through the imagination."
But the political impulse stayed, he says. Still stays. His recent novel Starbook, which reads almost like a fairy tale, is, at least in part, an allegory of the slave trade. If there's magic in his work, there are also hard edges. If he's writing fairy tales, they've got teeth. And if he is given to holding forth on the power of literature, it might just be because he knows something about it.
He arrived in England in the late 1970s to study comparative literature at the University of Essex on a grant from the Nigerian government. But when financial problems in Nigeria caused the grant to be withdrawn, Okri was homeless, sleeping on park benches, friends' floors, eating from restaurant bins. He has never written about this period, says perhaps he is "still digesting" it.
"It was a very, very important period. I was very young, and it seemed to be part of the tough romantic journey of being an artist. There was no bitterness. OK, there were moments when I found myself standing outside a restaurant and watching some famous writer eating lovely dishes of steak and so on. I actually remember that very distinctly, and being hurried away for looking in the window.
"But I wrote and wrote in that period, I wrote through the bitter winter nights. If anything (the desire to write] actually intensified. You only get through experiences like that either through fighting your way out of it and getting a job, or by an even more powerful belief in what it is you're doing.
"To sustain your belief through situations that completely undermine it is quite something. Looking back, I suppose I'm grateful I went through that because one is not too afraid of adversity. It's a reminder that life goes up and it goes down, but it's not whether it's up or down that counts, it's how much you love life. It's your inner fibre that counts."
Within a decade, at the age of 32, he was giving the victory address at the star-studded Booker Prize dinner. He had two earlier novels and two story collections to his name, but The Famished Road was like nothing else, a shimmering tour de force which, through the eyes of "spirit child" Azaro, moved fluidly between the gritty reality of African slums and the world of dreams, ghosts, imagination.
The book went on to sell half a million copies, and was translated into 15 languages. Unsurprisingly, it was hailed as the crest of a post-colonial wave, modernism meets Africa in an explosion of a new kind of magic realism – a term Okri has always rejected.
For the roots of The Famished Road were not only in Africa, but in his father's library of philosophy books. "That is the point that practically all my readers and practically all my critics have missed. At the heart of The Famished Road is a philosophical conundrum, for me, an essential one: what is reality? Everybody's reality is subjective, it's conditioned by upbringing, ideas, temperament, religion, what's happened to you."
Winning the Booker Prize propelled him into the big league, with the literary heavy-hitters. It bought him a kind of freedom to embark on writing which was more experimental. He speaks a writer's duty to "transform reality, while being truthful about life". For him, that meant finding new forms which could capture this strangeness, as well as the mundanity, of this thing we call life.
In his new book, Tales of Freedom, just out in paperback, he invented his own, the "stoku", a fusion of short story and haiku, pushing the groundedness of prose closer to the magical shimmer of poetry, "just to see if there's another way of touching the mysterious flash of human existence".
Which ends the circle where it began, with poetry, and a visit to the StAnza Poetry Festival later this month where he plans to read from the forthcoming collection. There are poems, he says, about all manner of subjects. "Classical poems. Poems about the cracks in modern life. Love poems. Tiny poems. Narrative poems. Done purely for themselves. It's a lovely thing to do and I don't know when I'll get this kind of freedom again."
• Ben Okri is In Conversation at the StAnza Poetry Festival, St Andrews, on Saturday 20 March at 3:30pm, see www.stanzapoetry.org. Tales of Freedom is out in paperback, published by Rider Books, price 7.99.