Friday, June 15, 1990, said the calendar now, shining at her. Way back in January she had written "15th birthday" on this page. She felt it was extra-special to be fifteen on the fifteenth. It would never happen again.

Fifteen! Wasn't this the first day of her adult life? She couldn't just go back to bed. Furthermore, it was the last day of school before the summer vacation. The students just had to appear in church at one o'clock. And what was more, in a week Dad would be home from Lebanon. He had promised to be home for Midsummer Eve.

Hilde stood by the window and looked out over the garden, down toward the dock behind the little red boat-house. The motorboat had not yet been brought out for the summer, but the old rowboat was tied up to the dock. She must remember to bail the water out of it after last night's heavy downpour.

Hilde Moller Knag awoke in the attic room in the old captain's house outside Lillesand. She glanced at the clock. It was only six o'clock, but it was already light. Broad rays of morning sun lit up the room.

… an old magic mirror Great-grandmother had bought from a Gypsy woman…

She got out of bed and went to the window. On the way she stopped by the desk and tore a page off her calendar. Thursday, June 14, 1990. She crumpled the page up and threw it in her wastebasket.

As she was looking out over the little bay, she remembered the time when as a little girl of six she had climbed up into the rowboat and rowed out into the bay alone. She had fallen overboard and it was all she could do to struggle ashore. Drenched to the skin, she had pushed her way through the thicket hedge. As she stood in the garden looking up at the house, her mother had come running toward her. The boat and both oars were left afloat in the bay. She still dreamed about the boat sometimes, drifting on its own, abandoned. It had been an embarrassing experience.

The garden was neither especially luxuriant nor particularly well kept. But it was large and it was Hilde's. A weather-beaten apple tree and a few practically barren fruit bushes had just about survived the severe winter storms. The old glider stood on the lawn between granite rocks and thicket. It looked so forlorn in the sharp morning light. Even more so because the cushions had been taken in. Mom had probably hurried out late last night and rescued them from the rain.

There were birch trees -- bj0rketreer -- all around the large garden, sheltering it partly, at least, from the worst squalls. It was because of those trees that the house had been renamed Bjerkely over a hundred years ago.

Hilde's great-grandfather had built the house some years before the turn of the century. He had been a captain on one of the last tall sailing ships. There were a lot of people who continued to call it the captain's house.

That morning the garden still showed signs of the heavy rain that had suddenly started late last evening. Hilde had been awakened several times by bursts of thunder. But today there was not a cloud in the sky.

Everything is so fresh after a summer storm like that. It had been hot and dry for several weeks and the tips of the leaves on the birch trees had started to turn yellow. Now it was as if the whole world had been newly washed. It seemed as if even her childhood had been washed away with the storm.

"Indeed, there is pain when spring buds burst…" Wasn't there a Swedish poet who had said something like that? Or was she Finnish?

Was she pretty? She wasn't ugly, anyway. Maybe she was kind of in-between…

Hilde stood in front of the heavy brass mirror hanging on the wall above Grandmother's old dresser.

She had long, fair hair. Hilde had always wished her hair could be either a bit fairer or a bit darker. This in-between color was so mousy. On the positive side, there were these soft curls. Lots of her friends struggled to get their hair to curl just a little bit, but Hilde's hair had always been naturally curly. Another positive feature, she thought, were her deep green eyes. "Are they really green?" her aunts and uncles used to say as they bent over to look at her.

Hilde considered whether the image she was studying was that of a girl or that of a young woman. She decided it was neither. The body might be quite womanly, but the face reminded her of an unripe apple.

There was something about this old mirror that always made Hilde think of her father. It had once hung down in the "studio." The studio, over the boathouse, was her father's combined library, writer's workshop, and retreat. Albert, as Hilde called him when he was home, had always wanted to write something significant. Once he had tried to write a novel, but he never finished it. From time to time he had had a few poems and sketches of the archipelago published in a national journal. Hilde was so proud every time she saw his name in print. ALBERT KNAG. It meant something in Lillesan^, anyway. Her great-grandfather's name had also been Albert.

Hilde had tried for ages, but it was just as hard to wink at yourself with both eyes as to run away from your own shadow. In the end she had been given the old family heirloom to keep. Through the years she had tried from time to time to master the impossible art.

The mirror. Many years ago her father had joked about not being able to wink at your own reflection with both eyes at the same time, except in this brass mirror. It was an exception because it was an old magic mirror Great-grandmother had bought from a Gypsy woman just after her wedding.

Not surprisingly, she was pensive today. And not unnaturally, she was preoccupied with herself. Fifteen years old…

Could this be the present? The great big present from Dad that had been so very secret? He had dropped so many cryptic hints in his cards from Lebanon. But he had "imposed a severe censorship on himself."

She happened to glance at her bedside table. There was a large package there. It had pretty blue wrapping and was tied with a red silk ribbon. It must be a birthday present!

The oddest hint had been that the present could perhaps be "shared with other people." He wasn't working for the UN for nothing! If her father had one bee in his bonnet -- and he had plenty -- it was that the. UN ought to be a kind of world government. May the UN one day really be able to unite the whole of humanity, he had written on one of his cards.

The present was something that "grew bigger and bigger," he had written. Then he had said something about a girl she was soon to meet -- and that he had sent copies of all his cards to her. Hilde had tried to pump her mother for clues, but she had no idea what he meant, either.

Was she allowed to open the package before her mother came up to her room singing "Happy Birthday to You," with pastry and a Norwegian flag? Surely that was why it had been put there?

She walked quietly across the room and picked up the package. It was heavy! She found the tag: To Hilde on her 15th birthday from Dad.

She sat on the bed and carefully untied the red silk ribbon. Then she undid the blue paper.

Had he written a whole book for her?

Was this her present? Was this the fifteenth-birthday present that there had been so much fuss about? The present that grew bigger and bigger and could be shared with other people?

It was a large ring binder.

A quick glance showed that the ring binder was rilled with typewritten pages. Hilde recognized them as being from her father's typewriter, the one he had taken with him to Lebanon.

On the first page, in large handwritten letters, was the title, SOPHIE'S WORLD.

Hilde turned to the next page, to the beginning of the first chapter. It was entitled "The Garden of Eden." She got into bed, sat up comfortably, resting the ring binder against her knees, and began to read.

Farther down the page there were two typewritten lines of poetry: TRUE ENLIGHTENMENT IS TO MAN LIKE SUNLIGHT TO THE SOIL -- N. F. S. Grundtvig

Sophie Amundsen was on her way home from school. She had walked the first part of the way with Joanna. They had been discussing robots. Joanna thought the human brain was like an advanced computer. Sophie was not certain she agreed. Surely a person was more than a piece of hardware?

Hilde read on and on. With surprise, she read about Sophie Amundsen receiving a postcard from Lebanon: "Hilde Moller Knag, c/o Sophie Amundsen, 3 Clover Close…"

Sophie's father was far from home, too. She was probably the girl Hilde would be getting to know…

Only by conjuring up an intense feeling of one day being dead could she appreciate how terribly good life was… Where does the world come from?… At some point something must have come from nothing. But was that possible? Wasn't that just as impossible as the idea that the world had always existed?

Dear Hilde, Happy 15th birthday. As I'm sure you'll understand, I want to give you a present that will help you grow. Forgive me for sending the card c/o Sophie. It was the easiest way. Love from Dad.

Hilde read on, oblivious of all else, even forgetting that it was her birthday. From time to time a brief thought crept in between the lines as she read: Had Dad written a book? Had he finally begun on the significant novel and completed it in Lebanon? He had often complained that time hung heavily on one's hands in that part of the world.

No, how could she?

Being interested in why we are here is not a "casual" interest like collecting stamps. People who ask such questions are taking part in a debate that has gone on as long as man has lived on this planet.

The joker! Hilde knew her father had always been a sly one, but today he had really taken her by surprise! Instead of tying the card on the package, he had written it into the book.

But poor Sophie! She must have been totally confused!

Why would a father send a birthday card to Sophie's address when it was quite obviously intended to go somewhere else? What kind of father would cheat his own daughter of a birthday card by purposely sending it astray? How could it be "the easiest way"? And above all, how was she supposed to trace this Hilde person?

Hilde turned a couple of pages and began to read the second chapter, "The Top Hat." She soon came to the long letter which a mysterious person had written to Sophie.

"Sophie was completely exhausted." So was Hilde. Not only had Dad written a book for her fifteenth birthday, he had written a strange and wonderful book.

To summarize briefly: A white rabbit is pulled out of a top hat. Because it is an extremely large rabbit, the trick takes many billions of years. All mortals are born at the very tip of the rabbit's fine hairs, where they are in a position to wonder at the impossibility of the trick. But as they grow older they work themselves ever deeper into the fur. And there they stay…

She read about the Greek natural philosophers. Hilde knew that her father was interested in philosophy. He had written an article in the newspaper proposing that philosophy should be a regular school subject. It was called "Why should philosophy be part of the school curriculum?" He had even raised the issue at a PTA meeting in Hilde's class. Hilde had found it acutely em-barrassing.

Sophie was not the only one who felt she had been on the point of finding herself a comfortable place deep down in the rabbit's fur.

Today was Hilde's fifteenth birthday, and she had the feeling it was time to decide which way she would choose to crawl.

She looked at the clock. It was seven-thirty. It would probably be half an hour before her mother came up with the breakfast tray, thank goodness, because right now she was engrossed in Sophie and all the philosophical questions. She read the chapter called "Democritus." First of all, Sophie got a question to think about: Why is Lego the most ingenious toy in the world? Then she found a large brown envelope in the mailbox: Democritus agreed with his predecessors that transformations in nature could not be due to the fact that anything actually "changed." He therefore assumed that everything was built up of tiny invisible blocks, each of which was eternal and immutable. Democritus called these smallest units atoms.

She had to smile as she read the P. P. S. in the philosophy teacher's letter to Sophie:

Hilde was indignant when Sophie found the red silk scarf under her bed. So that was where it was! But how could a scarf just disappear into a story? It had to be someplace…

If you should come across a red silk scarf anywhere, please take care of it. Sometimes personal property gets mixed up. Especially at school and places like that, and this is a philosophy school.

The chapter on Socrates began with Sophie reading "something about the Norwegian UN battalion in Lebanon" in the newspaper. Typical Dad! He was so concerned that people in Norway were not interested enough in the UN forces' peacekeeping task. If nobody else was, then Sophie would have to be. In that way he could write it into his story and get some sort of attention from the media.

Hilde heard her mother's footsteps on the stairs. Before she knocked on the door, Hilde had begun to read about Sophie's discovery of the video of Athens in her secret den.

"Happy birthday…" Her mother had begun to sing halfway up the stairs.

"Come in," said Hilde, in the middle of the passage where the philosophy teacher was talking directly to Sophie from the Acropolis. He looked almost exactly like Hilde's father -- with a "black, well-trimmed beard" and a blue beret.

"Uh-huh."

"Aren't you going to…?"

Hilde let the large ring binder slide down onto her lap.

"Hilde?"

"It's so amazing that those old temples are still standing. They are actually 2,500 years old. The biggest one is called the Virgin's Place, by the way."

"No, why do you ask?"

"Happy birthday, Hilde!"

"Have you ever been to Athens, Mom?"

"You can see I'm reading."

"Imagine, you're fifteen!"

"Have you opened your present from Dad?"

"What present?"

"You must look up now, Hilde. You're in a complete daze."

"Just put it there."

Her mother stood leaning over the bed with the tray. On it were lighted candles, buttered rolls with shrimp salad, and a soda. There was also a small package. Her mother stood awkwardly holding the tray with both hands, with a flag under one arm.

"Oh, thanks a lot, Mom. It's sweet of you, but I'm really busy."

Not until now did Hilde remember where she was, and her mother put the tray down on the bedside table.

They sat talking for a while.

Hilde got out of bed and gave her mother a hug.

For some reason Hilde felt embarrassed. "Oh, it's just a story."

Then Hilde said, "I have to get back to the book, Mom. Right now he's standing on top of the Acropolis."

"You don't have to go to school till one o'clock."

Hilde didn't want to be unfair, so she opened her mother's present right away. It was a gold bracelet.

"Well, I have to get to work. Don't forget to eat something. Your dress is on a hanger downstairs."

"Yes, a story. And a history of philosophy. Or something like that."

"A story?"

"Who is?"

"Sorry, Mom. I was completely absorbed in this."

"What is it he has written, Hilde? I've been just as mystified as you. It's been impossible to get a sensible word out of him for months."

"It's lovely, Mom! Thank you very much!"

"I've no idea. Neither has Sophie. That's the whole point."

"Aren't you going to open the package from me?"

Hilde shivered when the old buildings suddenly rose from the ruins. One of her father's pet ideas had been to let all the United Nations countries collaborate in reconstructing an exact copy of the Athenian square. It would be the forum for philosophical discussion and also for disarmament talks. He felt that a giant project like that would forge world unity. "We have, after all, succeeded in building oil rigs and moon rockets."

Then she read about Plato. "The soul yearns to fly home on the wings of love to the world of ideas. It longs to be freed from the chains of the body…"

Finally her mother disappeared down the stairs. So did Sophie's philosophy teacher; he walked down the steps from the Acropolis and stood on the Areopagos rock before appearing a little later in the old square of Athens.

Sophie had crawled through the hedge and followed Hermes, but the dog had escaped her. After having read about Plato, she had gone farther into the woods and come upon the red cabin by the little lake. Inside hung a painting of Bjerkely. From the description it was clearly meant to be Hilde's Bjerkely. But there was also a portrait of a man named Berkeley. "How odd!"

Berkeley, George, 1685-1753, Eng. Philos., Bishop of Cloyne. Denied existence of a material world beyond the human mind. Our sense perceptions proceed from God. Main work: A Treatise Concerning the Principles of Human Knowledge (1710).

Hilde laid the heavy ring binder aside on the bed and went over to her bookshelf and looked him up in the three-volume encyclopedia she had been given on her fourteenth birthday. Here he was -- Berkeley!

Yes, it was decidedly odd. Hilde stood thinking for a few seconds before going back to bed and the ring binder.

Berkeley was a philosopher who denied the existence of a material world beyond the human mind. That was certainly very strange, one had to admit. But it was not easy to disprove such claims, either. As regards Sophie, it fitted very well. After all, Hilde's father was respon-sible for her "sense perceptions."

In one way, it was her father who had hung the two pictures on the wall. Could there be any connection other than the similarity of names?

Well, she would know more if she read on. Hilde looked up from the ring binder and smiled when she got to the point where Sophie discovers the reflection of a girl who winks with both eyes. "The other girl had winked at Sophie as if to say: I can see you, Sophie. I am here, on the other side."

Sophie finds the green wallet in the cabin as well -- with the money and everything! How could it have made its way there?

Absurd! For a second or two Hilde had really believed that Sophie had found it. But then she tried to imagine how the whole thing must appear to Sophie. It must all seem quite inscrutable and uncanny.

For the first time Hilde felt a strong desire to meet Sophie face to face. She felt like telling her the real truth about the whole business.

But now Sophie had to get out of the cabin before she was caught red-handed. The boat was adrift on the lake, of course. (Her father couldn't resist reminding her of that old story, could he!)

Aristotle pointed out that nothing exists in consciousness that has not first been experienced by the senses. Plato would have said that there is nothing in the natural world that has not first existed in the world of ideas. Aristotle held that Plato was thus "doubling the number of things."

Hilde gulped a mouthful of soda and took a bite of her roll while she read the letter about the "meticulous" Aristotle, who had criticized Plato's theories.

Hilde had not known that it was Aristotle who had invented the game of "animal, vegetable, or mineral."

When she read about Aristotle's view of women she was both irritated and disappointed. Imagine being such a brilliant philosopher and yet such a crass idiot!

Aristotle wanted to do a thorough clearing up in nature's "room." He tried to show that everything in nature belongs to different categories and subcategories.

Aristotle had inspired Sophie to clean up her own room. And there, together with all the other stuff, she found the white stocking which had disappeared from Hilde's closet a month ago! Sophie put all the pages she had gotten from Alberto into a ring binder. "There were in all over fifty pages." For her own part, Hilde had gotten up to page 124, but then she also had Sophie's story on top of all the correspondence from Alberto Knox.

The next chapter was called "Hellenism." First of all, Sophie finds a postcard with a picture of a UN jeep. It is stamped UN Battalion, June 15. Another of these "cards" to Hilde that her father had put into the story instead of sending by mail.

P. S. Mom said you had lost your wallet. I hereby promise to reimburse you the 150 crowns. You will probably be able to get another school I. D. before they close for the summer vacation. Love from Dad.

Dear Hilde, I assume you are still celebrating your fifteenth birthday. Or is this the morning after? Anyway, it makes no difference to your present. In a sense, that will last a lifetime. But I'd like to wish you a happy birthday one more time. Perhaps you understand now why I send the cards to Sophie. I am sure she will pass them on to you.

Not bad! That made her 150 crowns richer. He probably thought a homemade present alone wasn't enough.

So it appeared that June 15 was Sophie's birthday, too. But Sophie's calendar had only gotten as far as the middle of May. That must have been when her father had written this chapter, and he had postdated the "birthday card" to Hilde. But poor Sophie, running down to the supermarket to meet Joanna.

Who was Hilde? How could her father as good as take it for granted that Sophie would find her? In any case, it was senseless of him to send Sophie the cards instead of sending them directly to his daughter.

This was not really something you needed to believe. It is so, thought Hilde. So everyone can read what they like into the word "divine."

I believe there is something of the divine mystery in everything that exists. We can see it sparkle in a sunflower or a poppy. We sense more of the unfathomable mystery in a butterfly that flutters from a twig -- or in a goldfish swimming in a bowl. But we are closest to God in our own soul. Only there can we become one with the greatest mystery of life. In truth, at very rare moments we can experience that we ourselves are that divine mystery.

She turned quickly to the next chapter. Sophie and Joanna go camping the night before the national holiday on May 17. They make their way to the major's cabin…

Hilde had not read many pages before she flung the bedclothes angrily aside, got up, and began to walk up and down, clutching the ring binder in her hands.

This was the most giddying passage Hilde had read up to now. But it was nevertheless the simplest. Everything is one, and this "one" is a divine mystery that everyone shares.

Hilde, like Sophie, was elevated to the celestial spheres as she read about Plotinus.

Sophie gets a new lesson from Alberto. It's all about Jews and Greeks and the two great cultures. Hilde liked getting this wide bird's-eye view of history. She had never learned anything like it at school. They only gave you details and more details. She now saw Jesus and Christianity in a completely new light.

Dear Hilde, I am now so bursting with all these secrets for your birthday that I have to stop myself several times a day from calling home and blowing the whole thing. It is something that simply grows and grows. And as you know, when a thing gets bigger and bigger it's more difficult to keep it to yourself…

She liked the quote from Goethe: "He who cannot draw on three thousand years is living from hand to mouth."

This was just about the most impudent trick she had ever heard of. In that little hut in the woods, her father lets these two girls find copies of all the cards he had sent Hilde in the first two weeks of May. And the copies were real enough. Hilde had read the very same words over and over. She recognized every single word.

Then Alberto calls Sophie, and this is the first time she hears his voice.

Dear Hilde, I don't know whether it will still be your birthday when you read this card. I hope so, in a way; or at least that not too many days have gone by. A week or two for Sophie does not have to mean just as long for us. I shall be coming home for Midsummer Eve, so we can sit together for hours in the glider, looking out over the sea, Hilde. We have so much to talk about…

"You make it sound like a war."

The next chapter began with a piece of card which sticks to Sophie's kitchen window. It is a new birthday card for Hilde, of course.

Maybe it wouldn't matter so much that she cut school on her birthday. But it did mean that her classmates wouldn't be celebrating with her. Oh well, she had always had plenty of well-wishers.

"I would rather call it a battle of wills. We have to attract Hilde's attention and get her over on our side before her father comes home to Lillesand."

And then Sophie meets Alberto Knox disguised as a medieval monk in the twelfth-century stone church.

Oh, no, the church! Hilde looked at the time. A quarter past one… She had forgotten all about the time.

When she read about how Sophia had appeared to Hildegard in visions, she turned once again to her encyclopedia. But this time she found nothing about either of them. Wasn't that typical! As soon as it was a question of women or something to do with women, the en-cyclopedia was about as informative as a moon crater. Was the whole work censored by the Society for the Protection of Men?

Hilde had never heard that God had a "female side" or a "mother nature." Her name was Sophia, apparently -- but she was apparently not worth printer's ink, either.

Hildegard of Bingen was a preacher, a writer, a doctor, a botanist, and a biologist. She was "perhaps an example of the fact that women were often more practical, more scientific even, in the Middle Ages."

But there was not a single word about her in the encyclopedia. How scandalous!

Soon she found herself receiving a long sermon. Alberto had no problem slipping into the role of a medieval priest.

The nearest she could find in the encyclopedia was an entry about the Santa Sophia Church in Constantinople (now Istanbul), named Hagia Sophia, which means Sacred Wisdom. But there was nothing about it being female. That was censorship, wasn't it?

When Sophie gets home after spending most of the morning in St. Mary's Church, she stands in front of the brass mirror she took home from the cabin in the woods.

Suddenly the other girl began to wink frantically with both eyes, as if to signal that she was really in there on the other side. The apparition lasted only a few seconds. Then she was gone.

Otherwise, it was true enough that Sophie had revealed herself to Hilde. She was picturing the girl with the straight hair all the time…

Wasn't it also a dark-haired woman she had been searching for? Great-grandmother had bought it from a Gypsy woman, hadn't she? Hilde felt her hands shaking as they held the book. She had the feeling that Sophie really existed somewhere "on the other side."

How many times had Hilde stood in front of the mirror like that as if she was searching for someone else behind the glass? But how could her father have known that?

She studied the sharp contours of her own pale face framed by that impossible hair which defied any style but nature's own. But beyond that face was the apparition of another girl.

Now Sophie is dreaming about Hilde and Bjerkely. Hilde can neither see nor hear her, but then -- Sophie finds Hilde's gold crucifix on the dock. And the crucifix -- with Hilde's initials and everything -- is in Sophie's bed when she wakes after her dream!

So she really had lost it. All right, but how had her father known it when she didn't even know it herself?

Hilde forced herself to think hard. Surely she hadn't lost her crucifix as well? She went to her dresser and took out her jewelry case. The crucifix, which she had received as a christening gift from her grandmother, was not there!

And another thing: Sophie had apparently dreamed that Hilde's father came home from Lebanon. But there was still a week to go before that happened. Was Sophie's dream prophetic? Did her father mean that when he came home Sophie would somehow be there? He had written that she would get a new friend…

In a momentary vision of absolute clarity Hilde knew that Sophie was more than just paper and ink. She really existed.