Oswald Mayer Sheffield (psychologist, thin as a string and as tall as a good length of it, and with a voice that could be used either for singing an operatic selection with surprising virtuosity or for making a point of argument, softly but with stinging accuracy) did not show the anger one would have expected from Vernadsky's account.

He was even smiling when he entered the Captain's cabin.

The Captain broke out mauvely as soon as he entered. "Look here, Sheffield-"

"One minute, Captain Follenbee," said Sheffield. "How are you, Mark?"

Mark's eyes fell and his words were muffled. "All right, Dr. Sheffield."

"I wasnt aware you'd gotten out of bed."

There wasn't the shade of reproach in his voice, but Mark grew apologetic. "I was feeling better, Dr. Sheffield, and I feel bad about not working. I haven't done anything in all the time I've been on the ship. So I put in a call to the Captain to ask to see the logbook and he had me come up here."

"All right I'm sure he won't mind if you go back to your room now."

"Oh, won't I?" began the Captain.

Sheffield's mild eyes rose to meet the Captain. "I'm responsible for him, sir."

And somehow the Captain could think of nothing further to say.

Mark turned obediently and Sheffield watched him leave and waited till the door was well closed behind him.

Then he turned again to the Captain. "What's the bloody idea, Captain?"

The Captain's knees bent a little, then straightened and bent again with a sort of threatening rhythm. The invisible slap of his hands, clasped behind his back, could be heard distinctly. "That's my question. I'm Captain here, Sheffield."

"I know that."

"Know what it means, eh? This ship, in space, is a legally recognized planet. I'm absolute ruler. In space, what I say goes. Central Committee of the Confederacy can't say otherwise. I've got to maintain discipline, and no spy-"

"All right, and now let me tell you something, Captain. You're chartered by the Bureau of Outer Provinces to carry a government-sponsored research expedition to the Lagrange System, to maintain it there as long as research necessity requires and the safety of the crew and vessel permits, and then to bring us home. You've signed that contract and you've assumed certain obligations, Captain or not. For instance, you can't tamper with our instruments and destroy their research usefulness."

"Who in space is doing that?" The Captain's voice was a blast of indignation.

Sheffield repied calmly, "You are. Hands off Mark Annuncio, Captain. Just as you've got to keep your bands off Cimon's monochrome and Vailleux's microptics, you've got to keep your hands off my Annuncio. And that means each one of your ten, four-striped fingers. Got it?"

The Captain's uniformed Chest expanded. "I take no order on board my own ship. Your language is a breach of discipline, Mister Sheffield. Any more like that and it's cabin arrest. You and your Annuncio. Don't like it, then speak to Board of Review back on Earth. Till then, it's tongue behind teeth."

"Look, Captain, let me explain something. Mark is in the Mnemonic Service-"

"Sure, he said so. Nummonic Service. Nummonic Service. It's plain secret police as far as I'm concerned. Well, not on board my ship, eh?"

"Mnemonic Service," said Sheffield patiently. "Em-en-ee-em-oh-en-eye-see Service. You don't pronounce the first em. It's from the Greek word meaning memory."

The Captain's eyes narrowed. "He remembers things?"

"Correct, Captain. Look, in a way this is my fault. I should have briefed you on this. I would have, too, if the boy hadn't gotten so sick right after the take-off. It drove most other matters out of my mind. Besides, it didn't occur to me that he might be interested in the workings of the ship itself. Space knows why not. He should be interested in everything."

"He should, eh?" The Captain looked at the timepiece on the wall. "Brief me now, eh? But no fancy words. Not many of any other kind, either. Time limited."

"It won't take long, I assure you. Now you're a space-going man, Captain. How many inhabited worlds would you say there were in the Confederation?"

"Eighty thousand," said the Captain promptly.

"Eighty-three thousand two hundred," said Sheffield. "What do you suppose it takes to run a political organization that size?"

Again the Captain did not hesitate. "Computers," he said.

"All right. There's Earth, where half the population works for the government and does nothing but compute and there are computing subcenters on every other world. And even so data gets lost. Every world knows something no other world knows. Almost every man. Look at our little group. Vernadsky doesn't know any biology and I don't know enough chemistry to stay alive. There's not one of us can pilot the simplest space cruiser, except for Fawkes. So we work together, each one supplying the knowledge the others lack.

"Only there's a catch. Not one of us knows exactly which of our own data is meaningful to the other under a given set of circumstances. We can't sit and spout every thing we know. So we guess, and sometimes we don't guess right. Two facts, A and B, can go together beautifully sometimes. So Person A, who knows Fact A, says to Person B, who knows Fact B, 'Why didn't you tell me this ten years ago?' and Person B answers, 'I didn't think it was important,' or, 'I thought everyone knew that.'".

The Captain said, "That's what computers are for."

Sheffield said, "Computers are limited, Captain. They have to be asked questions. What's more, the questions have to be the kind that can be put into a limited number of symbols. What's more, computers are very literal-minded. They answer exactly what you ask and not what you have in mind. Sometimes it never occurs to anyone to ask just the right question or feed the computer just the right symbols, and when that happens, the computer doesn't volunteer information.

"What we need, what all mankind needs, is a computer that is nonmechanical; a computer with imagination. There's one like that, Captain." The psychologist tapped his temple. "In everyone, Captain."

"Maybe," grunted the Captain, "but I'll stick to the usual, eh? Kind you punch a button."

"Are you sure? Machines don't have hunches. Did you ever have a hunch?"

"Is this on the point?" The Captain looked at the timepiece again.

Sheffield said, "Somewhere inside the human brain is a record of every datum that has impinged upon it. Very little of it is consciously remembered, but all of it's there, and a small association can bring an individual datum back without a person's knowing where it comes from. So you get a 'hunch' or a 'feeling.' Some people are better at it than others. And some can be trained. Some are almost perfect, like Mark Annuncio and a hundred like him. Someday, I hope, there'll be a billion like him, and we'l really have a Mnemonic Service.

"All their lives," Sheffield went on, "they do nothing but read, look, and listen. And train to do that better and more efficiently. It doesn't matter what data they collect. It doesn't have to have obvious sense or obvious significance. It doesn't matter if any man in the Service wants to spend a week going over the records of the space-polo teams of the Canopus Sector for the last century. Any datum may be useful someday. That's the fundamental axiom.

"Every once in a while one of the Service may correlate across a gap no machine could possibly manage. The machine would fail because no one machine is likely to possess those two pieces of thoroughly unconnected information, or else, if the machine does have them, no man would be insane enough to ask the right question. One good correlation out of the Service can pay for all the money appropriated for it in ten years or more."

The Captain raised his broad hand. He looked troubled. He said, "Wait a minute. Annuncio said no ship named Triple G. was under Earth registry. You mean he knows all registered ships by heart?"

"Probably," said Sheffield. "He may have read through the Merchant-Ship Register. If he did, he knows all the names, tonnages, years of construction, ports of call, numbers of crews, and anything else the register would contain."

"And he was counting stars."

"Why not? It's a datum."

"I'm damned."

"Perhaps, Captain. But the point is that a man like Mark is different from other men. He's got a queer, distorted upbringing and a queer, distorted view of life. This is the first time he's been" away from Service grounds since he entered them at the age of five. He's easily upset-and he can be ruined. That mustn't happen, and I'm in charge to see it doesn't. He's my instrument; a more valuable instrument than everything else on this entire ship baled into a neat little ball of plutonium wire. There are only a hundred like him in all the Milky Way."

Captain Follenbee assumed an air of wounded dignity. "All right, then. Logbook. Strictly confidential, eh?"

"Strictly. He talks only to me, and I talk to no one unless a correlation has been made."

The Captain did not look as though that fell under his classification of the word "strictly" but he said, "But no crew." He paused significantly. "You know what I mean."

Sheffield stepped to the door. "Mark knows about that. The crew won't hear about it from him, believe me."

And as he was about to leave, the Captain called out, "Sheffield!"

"Yes?"

"What in space is a noncompos?"

Sheffield suppressed a smile. "Did he call you that?"

"What is it?"

"Just short for non compos mentis. Everyone in the Service uses it for everyone not in the Service. You're one. I'm one. It's Latin for "not of sound mind." And you know, Captain- I think they're quite right."

He stepped out the door quickly.