“Then too,” said Dors with sudden enthusiasm, “suppose you work out psychohistory for a smaller society of the past and suppose you can make predictions from a study of the pre-Imperial situation as to what might happen a thousand years after the formation of the Empire-you could then check the actual situation at that time and see how near the mark you were.”

Hummin said coldly, “Considering that you would know in advance the situation of the year 1,000 of the Galactic Era, it would scarcely be a fair test. You would be unconsciously swayed by your prior knowledge and you would be bound to choose values for your equation in such a way as to give you what you would know to be the solution.”

“I don’t think so,” said Dors. “We don’t know the situation in 1,000 G.E. very well and we would have to dig. After all, that was eleven millennia ago.”

Seldon’s face turned into a picture of dismay. “What do you mean we don’t know the situation in 1,000 G.E. very well? There were computers then, weren’t there, Dors?”

“Of course.”

“And memory storage units and recordings of ear and eye? We should have all the records of 1,000 G.E. as we have of the present year of 12,020 G.E.”

“In theory, yes, but in actual practice- Well, you know, Hari, it’s what you keep saying. It’s possible to have full records of 1,000 G.E., but it’s not practical to expect to have it.”

“Yes, but what I keep saying, Dors, refers to mathematical demonstrations. I don’t see the applications to historical records.”

Dors said defensively, “Records don’t last forever, Hari. Memory banks can be destroyed or defaced as a result of conflict or can simply deteriorate with time. Any memory bit, any record that is not referred to for a long time, eventually drowns in accumulated noise. They say that fully one third of the records in the Imperial Library are simply gibberish, but, of course, custom will not allow those records to be removed. Other libraries are less tradition-bound. In the Streeling University library, we discard worthless items every ten years.

“Naturally, records frequently referred to and frequently duplicated on various worlds and in various libraries-governmental and private-remain clear enough for thousands of years, so that many of the essential points of Galactic history remain known even if they took place in pre-Imperial times. However, the farther back you go, the less there is preserved.”

“I can’t believe that,” said Seldon. “I should think that new copies would be made of any record in danger of withering. How could you let knowledge disappear?”

“Undesired knowledge is useless knowledge,” said Dors. “Can you imagine all the time, effort, and energy expended in a continual refurbishing of unused data? And that wastage would grow steadily more extreme with time.”

“Surely, you would have to allow for the fact that someone at some time might need the data being so carelessly disposed of.”

“A particular item might be wanted once in a thousand years. To save it all just in case of such a need isn’t cost-effective. Even in science. You spoke of the primitive equations of gravitation and say it is primitive because its discovery is lost in the mists of antiquity. Why should that be? Didn’t you mathematicians and scientists save all data, all information, back and back to the misty primeval time when those equations were discovered?”

Seldon groaned and made no attempt to answer. He said, “Well, Hummin, so much for my idea. As we look back into the past and as society grows smaller, a useful psychohistory becomes more likely. But knowledge dwindles even more rapidly than size, so psychohistory becomes less likely-and the less outweighs the more.”

“To be sure, there is the Mycogen Sector,” said Dors, musing.

Hummin looked up quickly. “So there is and that would be the perfect place to put Seldon. I should have thought of it myself.”

“Mycogen Sector,” repeated Hari, looking from one to the other. “What and where is Mycogen Sector?”

“Hari, please, I’ll tell you later. Right now, I have preparations to make. You’ll leave tonight.”

Dors had urged Seldon to sleep a bit. They would be leaving halfway between lights out and lights on, under cover of “night,” while the rest of the University slept. She insisted he could still use a little rest.

“And have you sleep on the floor again?” Seldon asked.

She shrugged. “The bed will only hold one and if we both try to crowd into it, neither of us will get much sleep.”

He looked at her hungrily for a moment and said, “Then I’ll sleep on the floor this time.”

“No, you won’t. I wasn’t the one who lay in a coma in the sleet.”

As it happened, neither slept. Though they darkened the room and though the perpetual hum of Trantor was only a drowsy sound in the relatively quiet confines of the University, Seldon found that he had to talk. He said, “I’ve been so much trouble to you, Dors, here at the University. I’ve even been keeping you from your work. Still, I’m sorry I’ll have to leave you.”

Dors said, “You won’t leave me. I’m coming with you. Hummin is arranging a leave of absence for me.”

Seldon said, dismayed, “I can’t ask you to do that.”

“You’re not. Hummin’s asking it. I must guard you. After all, I faded in connection with Upperside and should make up for it.”

“I told you. Please don’t feel guilty about that.-Still, I must admit I would feel more comfortable with you at my side. If I could only be sure I wasn’t interfering with your life…”

Dors said softly, “You’re not, Hari. Please go to sleep.”

Seldon lay silent for a while, then whispered, “Are you sure Hummin can really arrange everything, Dors?”

Dors said, “He’s a remarkable man. He’s got influence here at the University and everywhere else, I think. If he says he can arrange for an indefinite leave for me, I’m sure he can. He is a most persuasive man.”

“I know,” said Seldon. “Sometimes I wonder what he really wants of me.”

“What he says,” said Dors. “He’s a man of strong and idealistic ideas and dreams.”

“You sound as though you know him well, Dors.”

“Oh yes, I know him well.”

“Intimately?”

Dors made an odd noise. “I’m not sure what you’re implying, Hari, but, assuming the most insolent interpretation- No, I don’t know him intimately. What business would that be of yours anyway?”

“I’m sorry,” said Seldon. “I just didn’t want, inadvertently, to be invading someone else’s-”

“Property? That’s even more insulting. I think you had better go to sleep.”

“I’m sorry again, Dors, but I can’t sleep. Let me at least change the subject. You haven’t explained what the Mycogen Sector is. Why will it be good for me to go there? What’s it like?”

“It’s a small sector with a population of only about two million-if I remember correctly. The thing is that the Mycogenians cling tightly to a set of traditions about early history and are supposed to have very ancient records not available to anyone else. It’s just possible they would be of more use to you in your attempted examination of pre-Imperial times than orthodox historians might be. All our talk about early history brought the sector to mind.”

“Have you ever seen their records?”

“No. I don’t know anyone who has.”

“Can you be sure that the records really exist, then?”

“Actually, I can’t say. The assumption among non-Mycogenians is that they’re a bunch of madcaps, but that may be quite unfair. They certainly say they have records, so perhaps they do. In any case, we would be out of sight there. The Mycogenians keep strictly to themselves.-And now please do go to sleep.”

And somehow Seldon finally did.