So she’d walked and explored and inquired, and found nothing. But now, she thought, as she turned up the little track away from the olive grove, she would have to look for guidance.

Once she was far enough away from the little farmstead to be sure she wouldn’t be disturbed, she sat under the pine trees and opened her rucksack. At the bottom, wrapped in a silk scarf, was a book she’d had for twenty years: a commentary on the Chinese method of divination, the I Ching.

She had taken it with her for two reasons. One was sentimental: her grandfather had given it to her, and she had used it a lot as a schoolgirl. The other was that when Lyra had first found her way to Mary’s laboratory, she had asked: "What’s that?" and pointed to the poster on the door that showed the symbols from the I Ching; and shortly afterward, in her spectacular reading of the computer, Lyra had learned (she claimed) that Dust had many other ways of speaking to human beings, and one of them was the method from China that used those symbols.

So in her swift packing to leave her own world, Mary Malone had taken with her the Book of Changes, as it was called, and the little yarrow stalks with which she read it. And now the time had come to use them.

She spread the silk on the ground and began the process of dividing and counting, dividing and counting and setting aside, which she’d done so often as a passionate, curious teenager, and hardly ever since. She had almost forgotten how to do it, but she soon found the ritual coming back, and with it a sense of that calm and concentrated attention that played such an important part in talking to the Shadows.

Eventually she came to the numbers that indicated the hexagram she was being given, the group of six broken or unbroken lines, and then she looked up the meaning. This was the difficult part, because the Book expressed itself in such an enigmatic style.

She read:

Turning to the summit

For provision of nourishment

Brings good fortune.

Spying about with sharp eyes

Like a tiger with insatiable craving.

That seemed encouraging. She read on, following the commentary through the mazy paths it led her on, until she came to: Keeping still is the mountain; it is a bypath; it means little stones, doors, and openings.

She had to guess. The mention of "openings" recalled the mysterious window in the air through which she had entered this world; and the first words seemed to say that she should go upward.

Both puzzled and encouraged, she packed the book and the yarrow stalks away and set off up the path.

Four hours later she was very hot and tired. The sun was low over the horizon. The rough track she was following had petered out, and she was clambering with more and more discomfort among tumbled boulders and smaller stones. To her left the slope fell away toward a landscape of olive and lemon groves, of poorly tended vineyards and abandoned windmills, lying hazy in the evening light. To her right a scree of small rocks and gravel sloped up to a cliff of crumbling limestone. Wearily she hoisted her rucksack again and set her foot on the next flat stone—but before she even transferred her weight, she stopped. The light was catching something curious, and she shaded her eyes against the glare from the scree and tried to find it again.

And there it was: like a sheet of glass hanging unsupported in the air, but glass with no attention-catching reflections in it, just a square patch of difference. And then she remembered what the I Ching had said: a bypath… little stones, doors, and openings.

It was a window like the one in Sunderland Avenue in Oxford. She could only see it because of the light: with the sun any higher it probably wouldn’t show up at all.

She approached the little patch of air with passionate curiosity, because she hadn’t had time to look at the first one: she’d had to get away as quickly as possible. But she examined this one in detail, touching the edge, moving around to see how it became invisible from the other side, noting the absolute difference between this and that, and found her mind almost bursting with excitement that such things could be.

The knife bearer who had made it, at about the time of the American Revolution, had been too careless to close it, but at least he’d cut through at a point very similar to the world on this side: next to a rock face. But the rock on the other side was different, not limestone but granite, and as Mary stepped through into the new world she found herself not at the foot of a towering cliff but almost at the top of a low outcrop overlooking a vast plain.

It was evening here, too, and she sat down to breathe the air and rest her limbs and taste the wonder without rushing.

Wide golden light, and an endless prairie or savanna, like nothing she had ever seen in her own world. To begin with, although most of it was covered in short grass in an infinite variety of buff-brown-green-ocher-yellow-golden shades, and undulating very gently in a way that the long evening light showed up clearly, the prairie seemed to be laced through and through with what looked like rivers of rock with a light gray surface.

And secondly, here and there on the plain were stands of the tallest trees Mary had ever seen. Attending a high-energy physics conference once in California, she had taken time out to look at the great redwood trees, and marveled; but whatever these trees were, they would have overtopped the redwoods by half again, at least. Their foliage was dense and dark green, their vast trunks gold-red in the heavy evening light.

And finally, herds of creatures, too far off to see distinctly, grazed on the prairie. There was a strangeness about their movement that she couldn’t quite work out.

She was desperately tired, and thirsty and hungry besides. Somewhere nearby, though, she heard the welcome trickle of a spring, and only a minute later she found it: just a seepage of clear water from a mossy fissure, and a tiny stream that led away down the slope. She drank long and gratefully, and filled her bottles, and then set about making herself comfortable, for night was falling rapidly.

Propped against the rock, wrapped in her sleeping bag, she ate some of the rough bread and the goat’s cheese, and then fell deeply asleep.

She awoke with the early sun full in her face. The air was cool, and the dew had settled in tiny beads on her hair and on the sleeping bag. She lay for a few minutes lapped in freshness, feeling as if she were the first human being who had ever lived.

She sat up, yawned, stretched, shivered, and washed in the chilly spring before eating a couple of dried figs and taking stock of the place.

Behind the little rise she had found herself on, the land sloped gradually down and then up again; the fullest view lay in front, across that immense prairie. The long shadows of the trees lay toward her now, and she could see flocks of birds wheeling in front of them, so small against the towering green canopy that they looked like motes of dust.

Loading her rucksack again, she made her way down onto the coarse, rich grass of the prairie, aiming for the nearest stand of trees, four or five miles away.

The grass was knee-high, and growing among it were low-lying bushes, no higher than her ankles, of something like juniper; and there were flowers like poppies, like buttercups, like cornflowers, giving a haze of different tints to the landscape; and then she saw a large bee, the size of the top segment of her thumb, visiting a blue flower head and making it bend and sway. But as it backed out of the petals and took to the air again, she saw that it was no insect, for a moment later it made for her hand and perched on her finger, dipping a long needle-like beak against her skin with the utmost delicacy and then taking flight again when it found no nectar. It was a minute hummingbird, its bronze-feathered wings moving too fast for her to see.