 as hare and empty as a blackboard before the teacher arrives

Sophie arrived home at eight-thirty. That was one and a half hours after the agreement--which was not really an agreement. She had simply skipped dinner and left a message for her mother that she would be back not later than seven.

"This has got to stop, Sophie. I had to call information and ask if they had any record of anyone named Alberto in the Old Town. They laughed at me."

"I couldn\'t get away. I think we\'re just about to make a breakthrough in a huge mystery."

"Nonsense!"

"It\'s true!"

"Did you invite him to your party?"

"Oh no, I forgot."

"Well, now I insist on meeting him. Tomorrow at the latest. It\'s not natural for a young girl to be meeting an older man like this."

"You\'ve got no reason to be scared of Alberto. It may be worse with Hilde\'s father."

"Who\'s Hilde?"

"The daughter of the man in Lebanon. He\'s really bad. He may be controlling the whole world."

"If you don\'t immediately introduce me to your Alberto, I won\'t allow you to see him again. I won\'t feel easy about him until I at least know what he looks like."

Sophie had a brilliant idea and dashed up to her room.

"What\'s the matter with you now?" her mother called after her.

In a flash Sophie was back again.

"In a minute you\'ll see what he looks like. And then I hope you\'ll let me be."

She waved the video cassette and went over to the VCR.

"Did he give you a video?"

"From Athens..."

Pictures of the Acropolis soon appeared on the screen. Her mother sat dumbfounded as Alberto came forward and began to speak directly to Sophie.

Sophie now noticed something she had forgotten about. The Acropolis was crowded with tourists milling about in their respective groups. A small placard was being held up from the middle of one group. On it was written HILDE ... Alberto continued his wandering on the Acropolis. After a while he went down through the entrance and climbed to the Areopagos hill where Paul had addressed the Athenians. Then he went on to talk to Sophie from the square.

Her mother sat commenting on the video in short utterances:

"Incredible... is that Alberto? He mentioned the rabbit again... But, yes, he\'s really talking to you, Sophie. I didn\'t know Paul went to Athens ..."

The video was coming to the part where ancient Athens suddenly rises from the ruins. At the last minute Sophie managed to stop the tape. Now that she had shown her mother Alberto, there was no need to introduce her to Plato as well.

There was silence in the room.

"What do you think of him? He\'s quite good-looking, isn\'t he?" teased Sophie.

"What a strange man he must be, having himself filmed in Athens just so he could send it to a girl he hardly knows. When was he in Athens?"

"I haven\'t a clue."

"But there\'s something else ..."

"What?"

 "He looks very much like the major who lived in that little hut in the woods."

"Well maybe it is him, Mom."

"But nobody has seen him for over fifteen years."

"He probably moved around a lot... to Athens, maybe."

Her mother shook her head. "When I saw him sometime in the seventies, he wasn\'t a day younger than this Alberto I just saw. He had a foreign-sounding name..."

"Knox?"

"Could be, Sophie. Could be his name was Knox."

"Or was it Knag?"

"I can\'t for the life of me remember ... Which Knox or Knag are you talking about?"

"One is Alberto, the other is Hilde\'s father."

"It\'s all making me dizzy."

"Is there any food in the house?"

"You can warm up the meatballs."

Exactly two weeks went by without Sophie hearing a word from Alberto. She got another birthday card for Hilde, but although the actual day was approaching, she did not receive a single birthday card herself.

One afternoon she went to the Old Town and knocked on Alberto\'s door. He was out, but there was a short note attached to his door. It said:

Happy birthday, Hilde! Now the great turning point is at hand. The moment of truth, little one. Every time I think about it, I can\'t stop laughing. It has naturally something to do with Berkeley, so hold on to your hat.

Sophie tore the note off the door and stuffed it into Alberto\'s mailbox as she went out.

Damn! Surely he\'d not gone back to Athens? How could he leave her with so many questions unanswered?

When she got home from school on June 14, Hermes was romping about in the garden. Sophie ran toward him and he came prancing happily toward her. She put her arms around him as if he were the one who could solve all the riddles.

Again she left a note for her mother, but this time she put Alberto\'s address on it.

As they made their way across town Sophie thought about tomorrow. Not about her own birthday so much-- that was not going to be celebrated until Midsummer Eve anyway. But tomorrow was Hilde\'s birthday too. Sophie was convinced something quite extraordinary would happen. At least there would be an end to all those birthday cards from Lebanon.

When they had crossed Main Square and were making for the Old Town, they passed by a park with a playground. Hermes stopped by a bench as if he wanted Sophie to sit down.

She did, and while she patted the dog\'s head she looked into his eyes. Suddenly the dog started to shudder violently. He\'s going to bark now, thought Sophie.

Then his jaws began to vibrate, but Hermes neither growled nor barked. He opened his mouth and said:

"Happy birthday, Hilde!"

Sophie was speechless. Did the dog just talk to her? Impossible, she must have imagined it because she was thinking of Hilde. But deep down she was nevertheless convinced that Hermes had spoken, and in a deep resonant bass voice.

The next second everything was as before. Hermes gave a couple of demonstrative barks--as if to cover up the fact that he had just spoken with a human voice-- and trotted on ahead toward Alberto\'s place. As they were going inside Sophie looked up at the sky. It had been fine weather all day but now heavy clouds were beginning to gather in the distance.

Alberto opened the door and Sophie said at once:

"No civilities, please. You are a great idiot, and you know it."

"What\'s the matter now?"

"The major taught Hermes to talk!"

"Ah, so it has come to that."

"Yes, imagine!"

"And what did he say?"

 "I\'ll give you three guesses."

"I imagine he said something along the lines of Happy Birthday!"

"Bingo."

Alberto let Sophie in. He was dressed in yet another costume. It wasn\'t all that different from last time, but today there were hardly any braidings, bows, or lace.

"But that\'s not all," Sophie said.

"What do you mean?"

"Didn\'t you find the note in the mailbox?"

"Oh, that. I threw it away at once."

"I don\'t care if he laughs every time he thinks of Berkeley. But what is so funny about that particular philosopher?"

"We\'ll have to wait and see."

"But today is the day you\'re going to talk about him, isn\'t it?"

"Yes, today is the day."

Alberto made himself comfortable on the sofa. Then he said:

"Last time we sat here I told you about Descartes and Spinoza. We agreed that they had one important thing in common, namely, that they were both rationalists."

"And a rationalist is someone who believes strongly in the importance of reason."

"That\'s right, a rationalist believes in reason as the primary source of knowledge, and he may also believe that man has certain innate ideas that exist in the mind prior to all experience. And the clearer such ideas may be, the more certain it is that they correspond to reality. You recall how Descartes had a clear and distinct idea of a \'perfect entity,\' on the basis of which he concluded that God exists."

"I am not especially forgetful."

"Rationalist thinking of this kind was typical for philosophy of the seventeenth century. It was also firmly rooted in the Middle Ages, and we remember it from Plato and Socrates too. But in the eighteenth century it was the object of an ever increasing in-depth criticism. A number of philosophers held that we have absolutely nothing in the mind that we have not experienced through the senses. A view such as this is called empiricism."

"And you are going to talk about them today, these empiricists?"

"I\'m going to attempt to, yes. The most important empiricists--or philosophers of experience--were Locke, Berkeley, and Hume, and all three were British. The leading rationalists in the seventeenth century were Descartes, who was French; Spinoza, who was Dutch; and Leibniz, who was German. So we usually make a distinction between British empiricism and Continental rationalism."

"What a lot of difficult words! Could you re............