Marilynne Robinson is a magician.

A snake charmer. She mesmerizes you. She conjures with the basic materials, the molecular building blocks of America: rivers, stars, smoke, taffy, soil and wet grass. Popcorn. Schoolrooms and birds and berries and lanterns. The main action of Lila takes place in the late 1940s, in and around the small Iowa town of Gilead, the locus of Robinson's excellent last two novels, Gilead and Home. But much of the emotional power of this book comes from what happened to the principal characters during the previous decade.

Lila is very young when she is stolen from some people who are badly neglecting her (it's never clear if they are her parents). She is spirited away by a determined woman, with an injured face, known as 'Doll'. Homeless and virtually possessionless, they join a loose family of sharecroppers. The winds of the Dust Bowl begin to blow, and life becomes wickedly hard. What this means is that Doll and Lila lead a life that is almost completely out of doors, and in this is the compelling poetry of Lila, which is concerned with the astonishing facts of existence and consciousness. That these are its subjects is what makes it great, from the very beginning.

Robinson has the art of timelessness - it's almost impossible to figure out in what decade or even century Lila occurs. Because, almost impossibly, the story takes place in the actual, real world, we suffer it without the signposts of industrial artifacts. It's fascinating. Finally a tiny clue arrives, in the title of a movie playing in town: The Treasure Of The Sierra Madre. Lila is relieved when the men start shooting because she knows the picture will be over soon. She prefers tap dancing.

The feeling for the physical world is so strong in this novel. In fact it's dedicated "To IOWA". There's a similar violence to Leon Rooke's brilliant and frightening novel A Good Baby, in which he's lashed his characters to rainy Carolina hillsides. In the stillness of Robinson's American language you can hear Steinbeck, too, and in Lila's cherishably awkward take on the world, the intricate steeliness of Flannery O'Connor.

Here is Lila's memory of a storm she endured as a child: "There was that one time the wind came with thunder and rain and scared them half to death. The ground shook. There was lightning everywhere. Leaves and shingles and window curtains sailed over them, falling around them. Mellie lay on her back to watch, so Lila did, too, wiping filthy rain out of her eyes. There were things never meant to fly, books and shoes and chickens and washboards, caught up in the wind as if they were escaping at last, at last, from having to be whatever they were." There is such genuine human transference of knowledge and experience in Lila, something very few writers achieve.

The story of a woman who fears that she is the one person in the world who can't make sense of it, the narrative of Lila trails in and around itself, like the way we think about our own lives. The present is always part of the past, because we tell our story to ourselves. As a reader you feel very well looked after by Marilynne Robinson: you are knocked out by the weight of thought, the care, the worry she puts into her work. You find yourself wandering into vast new rooms, as if you're in a fabulous museum you've dreamt up for your own pleasure. There's really no one else writing like this today.

Lila is never physically described: we usually only know if she's clean or dirty, and whether she's shod or not. But there's an anarchic, pressing logic to her personality, somewhat like Bertha's in Fannie Hurst's Lummox, which makes her unforgettable. And Robinson always takes her side. Doll, too, is a real force. She recurs in many ways. She kills. She is wise. "Don't want what you don't need and you'll be fine," she tells Lila. And she reaches an apotheosis. Her determination, all her life, is to look after Lila, to keep this child she stole almost physically attached to herself.

Later, Lila has spent a few years in a whorehouse in St Louis: never very good at this, she's become more the janitor of the place. When one of the prostitutes becomes pregnant, Lila fantasizes about stealing that baby in turn and returning to the hazards of nature ("She'd be out in the weather again…") which is the only life that makes sense to her. But she escapes the city alone and arrives at a derelict cottage on the outskirts of Gilead, where she soon meets an older man, the Reverend John Ames. It's as if Lila has just arrived from some other planet. She knows how to read, thanks to Doll putting her in a school for a year, but she never has read anything. So both the Bible and the Sears Roebuck mail-order catalogue are revelations to her. Reverend Ames is seeing out his days as a pastor; when he meets Lila he realizes he knows nothing. They fall in love in the most dazzling, tortuous way.

Lila begins to read The Book of Job, to Ames, one of the most difficult parts of the Bible. To her, having lived through the Depression with Doll, without a roof, it makes perfect sense: "She never expected to find so many things she already knew about written down in a book." And she says to herself, "You'd think a man as careful as this Job might have had a storm cellar." Yes, you are very definitely being sold something in Robinson's novels: God. I don't like God and I hate it when he has to be part of a work of art. But I don't care, because Lila is just so damnably beautiful.

Marilynne Robinson will be speaking at 3pm on November 16 at the Assembly Roxy in Edinburgh. Tickets cost £9 and are only available from Edinburgh International Book Festival on www.edbookfest.co.uk/the-festival/whats-on/marilynne-robinson or from 0131 718 5666.