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

"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."

"Nonsense!"

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

"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."

"It's true!"

"Oh no, I forgot."

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.

"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."

"Who's Hilde?"

"Did you invite him to your party?"

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

In a flash Sophie was back again.

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

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

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

"Did he give you a video?"

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

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.

"From Athens…"

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

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

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…"

"I haven't a clue."

"Or was it Knag?"

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.

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

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?"

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

"What?"

"Well maybe it is him, Mom."

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

"But there's something else…"

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

"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?"

There was silence in the room.

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

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

"It's all making me dizzy."

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

"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.

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

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

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.

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.

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.

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.

Then his jaws began to vibrate, but Hermes neither growled nor barked.

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.

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

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

"What's the matter now?"

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

"The major taught Hermes to talk!"

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.

Alberto opened the door and Sophie said at once: "No civilities, please. You are a great idiot, and you know it."

"What do you mean?"

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

"Bingo."

"And what did he say?"

"I'll give you three guesses."

"Yes, imagine!"

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.

"Ah, so it has come to that."

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

"Yes, today is the day."

"We'll have to wait and see."

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

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

"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."

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."

"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?"

"What a lot of difficult words! Could you repeat the meaning of empiricism?"

"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."

"An empiricist will derive all knowledge of the world from what the senses tell us. The classic formulation of an empirical approach came from Aristotle. He said: 'There is nothing in the mind except what was first in the senses.' This view implied a pointed criticism of Plato, who had held that man brought with him a set of innate 'ideas' from the world of ideas. Locke repeats Aristotle's words, and when Locke uses them, they are aimed at Descartes."

"There is nothing in the mind… except what was first in the senses?"

"And that particle of gold is real experience?"

"We have no innate ideas or conceptions about the world we are brought into before we have seen it. If we do have a conception or an idea that cannot be related to experienced facts, then it will be a false conception. When we, for instance, use words like 'God,"eternity,' or 'substance,' reason is being misused, because nobody has experienced God, eternity, or what philosophers have called substance. So therefore many learned dissertations could be written which in actual fact contain no really new conceptions. An ingeniously contrived philosophical system such as this may seem impressive, but it is pure fantasy. Seventeenth- and eighteenth-century philosophers had inherited a number of such learned dissertations. Now they had to be examined under a microscope. They had to be purified of all hollow notions. We might compare it with panning for gold. Most of what you fish up is sand and clay, but in between you see the glint of a particle of gold."

"Or at least thoughts that can be related to experience. It became a matter of great importance to the British empiricists to scrutinize all human conceptions to see whether there was any basis for them in actual experience. But let us take one philosopher at a time."

"The first was the Englishman John Locke, who lived from 1632 to 1704. His main work was the Essay Concerning Human Understanding, published in 1690. In it he tried to clarify two questions. First, where we get our ideas from, and secondly, whether we can rely on what our senses tell us."

"That was some project!"

"You can skip the Latin."

"Okay, shoot!"

"We'll take these questions one at a time. Locke's claim is that all our thoughts and ideas issue from that which we have taken in through the senses. Before we perceive anything, the mind is a 'tabula rasa'-- or an empty slate."

"Before we sense anything, then, the mind is as bare and empty as a blackboard before the teacher arrives in the classroom. Locke also compared the mind to an unfurnished room. But then we begin to sense things. We see the world around us, we smell, taste, feel, and hear. And nobody does this more intensely than infants. In this way what Locke called simple ideas of sense arise. But the mind does not just passively receive information from outside it. Some activity happens in the mind as well. The single sense ideas are worked on by thinking, reasoning, believing, and doubting, thus giving rise to what he calls reflection. So he distinguished between 'sensation' and 'reflection.' The mind is not merely a passive receiver. It classifies and processes all sensations as they come streaming in. And this is just where one must be on guard."

"Locke emphasized that the only things we can perceive are simple sensations. When I eat an apple, for example, I do not sense the whole apple in one single sensation. In actual fact I receive a whole series of simple sensations -- such as that something is green, smells fresh, and tastes juicy and sharp. Only after I have eaten an apple many times do I think: Now I am eating an 'apple.' As Locke would say, we have formed a complex idea of an 'apple.' When we were infants, tasting an apple for the first time, we had no such complex idea. But we saw something green, we tasted something fresh and juicy, yummy… It was a bit sour too. Little by little we bundle many similar sensations together and form concepts like 'apple,"pear,"orange.' But in the final analysis, all the material for our knowledge of the world comes to us through sensations. Knowledge that cannot be traced back to a simple sensation is therefore false knowledge and must consequently be rejected."

"At any rate we can be sure that what we see, hear, smell, and taste are the way we sense it."

"On guard?"

"I didn't say a word."

"Locke distinguished between what he called 'primary' and 'secondary' qualities. And in this he acknowledged his debt to the great philosophers before him -- including Descartes. By primary qualities he meant extension, weight, motion and number, and so on. When it is a question of qualities such as these, we can be certain that the senses reproduce them objectively. But we also sense other qualities in things. We say that something is sweet or sour, green or red, hot or cold. Locke calls these secondary qualities. Sensations like these -- color, smell, taste, sound -- do not reproduce the real qualities that are inherent in the things themselves. They reproduce only the effect of the outer reality on our senses."

"Both yes and no. And that brings us to the second question Locke tried to answer. He had first answered the question of where we get our ideas from. Now he asked whether the world really is the way we perceive it. This is not so obvious, you see, Sophie. We mustn't jump to conclusions. That is the only thing a real philosopher must never do."

"Exactly. Everyone can agree on the primary qualities like size and weight because they lie within the objects themselves. But the secondary qualities like color and taste can vary from person to person and from animal to animal, depending on the nature of the individual's sensations."

"And neither one of you is right or wrong. You are just describing how the orange affects your senses. It's the same with the sense of color. Maybe you don't like a certain shade of red. But if Joanna buys a dress in that color it might be wise to keep your opinion to yourself. You experience the color differently, but it is neither pretty nor ugly."

"When Joanna eats an orange, she gets a look on her face like when other people eat a lemon. She can't take more than one segment at a time. She says it tastes sour. I usually think the same orange is nice and sweet."

"Everyone to his own taste, in other words."

"But everyone can agree that an orange is round."

"Yes, if you have a round orange, you can't 'think' it is square. You can 'think' it is sweet or sour, but you can't 'think' it weighs eight kilos if it only weighs two hundred grams. You can certainly 'believe' it weighs several kilos, but then you'd be way off the mark. If several people have to guess how much something weighs, there will always be one of them who is more right than the others. The same applies to number. Either there are 986 peas in the can or there are not. The same with motion. Either the car is moving or it's stationary."

"I get it."

"Locke admitted what he called intuitive, or 'demonstrative,' knowledge in other areas too. For instance, he held that certain ethical principles applied to everyone. In other words, he believed in the idea of a natural right, and that was a rationalistic feature of his thought. An equally rationalistic feature was that Locke believed that it was inherent in human reason to be able to know that God exists."

"So when it was a question of 'extended' reality, Locke agreed with Descartes that it does have certain qualities that man is able to understand with his reason."

"Maybe he was right."

"About what?"

"It is possible, of course. But he did not let it rest on faith. He believed that the idea of God was born of human reason. That was a rationalistic feature. I should add that he spoke out for intellectual liberty and tolerance. He was also preoccupied with equality of the sexes, maintaining that the subjugation of women to men was 'man-made.' Therefore it could be altered."

"It shouldn't be so difficult to agree on that."

"That God exists."

"Locke was one of the first philosophers in more recent times to be interested in sexual roles. He had a great influence on John Stuart Mill, who in turn had a key role in the struggle for equality of the sexes. All in all, Locke was a forerunner of many liberal ideas which later, during the period of the French Enlightenment in the eighteenth century, came into full flower. It was he who first advocated the principle of division of powers…"

"This division of power originated from the French Enlightenment philosopher Montesquieu. Locke had first and foremost emphasized that the legislative and the executive power must be separated if tyranny was to be avoided. He lived at the time of Louis XIV, who had assembled all power in his own hands. 'I am the State,' he said. We say he was an 'absolute' ruler. Nowadays we would call Louis XIV's rule lawless and arbitrary. Locke's view was that to ensure a legal State, the people's representatives must make the laws and the king or the government must apply them."

"I can't disagree there."

"Isn't that when the power of the state is divided between different institutions?"

"Do you remember which institutions?"

"There's the legislative power, or elected representatives. There's the judicial power, or law courts, and then there's the executive power, that's the government."