"Anderson may hold the clue to these questions and many others," Fermeti said. "But our central problem remains the same. We must induce him to complete the mass-restoration formula in precise mathematical terms, rather than vague, poetic allusions."
Thoughtfully, Tozzo said, "He's a brilliant man, that Anderson. Look at the ease by which he eluded us."
"Yes," Fermeti agreed. "We mustn't underestimate him. We did that, and it's rebounded." His face was grim.
Hurrying up the almost-deserted sidestreet, Poul Anderson wondered why the woman had regarded him as sick. And the mention of children had set off the clerk in the store, too. Was birth illegal now? Or was it regarded as sex had been once, as something too private to speak of in public?
In any case, he realized, if I plan to stay here I've got to shave my head. And, if possible, acquire different clothing.
There must be barbershops. And, he thought, the coins in my pockets; they're probably worth a lot to collectors.
He glanced about, hopefully. But all he saw were tall, luminous plastic and metal buildings which made up the city, structures in which incomprehensible transactions took place. They were as alien to him as--
Alien, he thought, and the word lodged chokingly in his mind. Because something had oozed from a doorway ahead of him. And now his way was blocked--deliberately, it seemed--by a slime mold, dark yellow in color, as large as a human being, palpitating visibly on the sidewalk. After a pause the slime mold undulated toward at him at a regular, slow rate. A human evolutionary development? Poul Anderson wondered, recoiling from it. Good Lord ... and then he realized what he was seeing.
This era had space travel. He was seeing a creature from another planet.
"Um," Poul said, to the enormous mass of slime mold, "can I bother you a second to ask a question?"
The slime mold ceased to undulate forward. And in Poul's brain a thought formed which was not his own. "I catch your query. In answer: I arrived yesterday from Callisto. But I also catch a number of unusual and highly interesting thoughts in addition... you are a time traveler from the past." The tone of the creature's emanations was one of considerate, polite amusement--and interest.
"Yes," Poul said. "From 1954."
"And you wish to find a barbershop, a library and a school. All at once, in the precious time remaining before they capture you." The slime mold seemed solicitous. "What can I do to help you? I could absorb you, but it would be a permanent symbiosis, and you would not like that. You are thinking of your wife and child. Allow me to inform you as to the problem regarding your unfortunate mention of children. Terrans of this period are experiencing a mandatory moratorium on childbirth, because of the almost infinite sporting of the previous decades. There was a war, you see. Between Gutman's fanatical followers and the more liberal legions of General McKinley. The latter won."
Poul said, "Where should I go? I'm confused." His head throbbed and he felt tired. Too much had happened. Just a short while ago he had been standing with Tony Boucher in the Sir Francis Drake Hotel, drinking and chatting... and now this. Facing this great slime mold from Callisto. It was difficult--to say the least--to make such an adjustment.
The slime mold was transmitting to him. "I am accepted here while you, their ancestor, are regarded as odd. Ironic. To me, you look quite like them, except for your curly brown hair and of course your silly clothing." The creature from Callisto pondered. "My friend, the polpol are the political police, and they search for deviants, followers of the defeated Gutman, who are terrorists now, and hated. Many of these followers are drawn from the potentially criminal classes. That is, the non-conformists, the so-called introves. Individuals who set their own subjective value-system up in place of the objective system in vogue. It is a matter of life and death to the Terrans, since Gutman almost won."
"I'm going to hide," Poul decided.
"But where? You can't really. Not unless you wish to go underground and join the Gutmanites, the criminal class of bomb-throwers... and you won't want to do that. Let us stroll together, and if anyone challenges you, I will say you're my servant. You have manual extensors and I have not. And I have, by a quirk, decided to dress you oddly and to have you retain your head-hair. The responsibility then becomes mine. It is actually not unusual for higher out-world organisms to employ Terran help."
"Thanks," Poul said tautly, as the slime mold resumed its slow forward motion along the sidewalk. "But there are things I want to do--"
"I am on my way to the zoo," the slime mold continued. An unkind thought came to Poul.
"Please," the slime mold said. "Your anachronistic twentieth century humor is not appreciated. I am not an inhabitant of the zoo; it is for life forms of low mental order such as Martian glebs and trawns. Since the initiation of interplanetary travel, zoos have become the center of--"
Poul said, "Could you lead me to the space terminal?" He tried to make his request sound casual.
"You take a dreadful risk," the slime mold said, "in going to any public place. The polpol watch constantly."
"I still want to go." If he could board an interplanetary ship, if he could leave Earth, see other worlds--
But they would erase his memory; all at once he realized that, in a rush of horror. I've got to make notes, he told himself. At once!
"Do, um, you have a pencil?" he asked the slime mold. "Oh, wait; I have one. Pardon me." Obviously the slime mold didn't.
On a piece of paper from his coat pocket--it was convention material of some sort--he wrote hurriedly, in brief, disjointed phrases, what had happened to him, what he had seen in the twenty-first century. Then he quickly stuck the paper back in his pocket.
"A wise move," the slime mold said. "And now to the spaceport, if you will accompany me at my slow pace. And, as we go, I will give you details of Terra's history from your period on." The slime mold moved down the sidewalk. Poul accompanied it eagerly; after all, what choice did he have? "The Soviet Union. That was tragic. Their war with Red China in 1983 which finally involved Israel and France... regrettable, but it did solve the problem of what to do with France--a most difficult nation to deal with in the latter half of the twentieth century."
On his piece of paper Poul jotted that down, too.
"After France had been defeated--" The slime mold went on, as Poul scratched against time.
Fermeti said, "We must glin, if we're to catch Anderson before he boards a ship." And by "glin" he did not mean glinning a little; he meant a full search with the cooperation of the polpol. He hated to bring them in, and yet their help now seemed vital. Too much time had passed and Anderson had not yet been found.
The spaceport lay ahead, a great disk miles in diameter, with no vertical obstructions. In the center was the Burned Spot, seared by years of tail-exhausts from landing and departing ships. Fermeti liked the spaceport, because here the denseness of the close-packed buildings of the city abruptly ceased. Here was openness, such as he recalled from childhood... if one dared to think openly of childhood.
The terminal building was set hundreds of feet beneath the rexeroid layer built to protect the waiting people in case of an accident above. Fermeti reached the entrance of the descent ramp, then halted impatiently to wait for Tozzo and Gilly to catch up with him.
"I'll nilp," Tozzo said, but without enthusiasm. And he broke the band on his wrist with a single decisive motion.
The polpol ship hovered overhead at once.
"We're from the Emigration Bureau," Fermeti explained to the polpol lieutenant. He outlined their Project, described--reluctantly--their bringing Poul Anderson from his time-period to their own.
"Hair on head," the polpol lieutenant nodded. "Quaint duds. Okay, Mr. Fermeti; we'll glin until we find him." He nodded, and his small ship shot off.
"They're efficient," Tozzo admitted.
"But not likeable," Fermeti said, finishing Tozzo's thought.
"They make me uncomfortable," Tozzo agreed. "But I suppose they're supposed to."
 
; The three of them stepped onto the descent ramp--and dropped at breathtaking speed to level one below. Fermeti shut his eyes, wincing at the loss of weight. It was almost as bad as takeoff itself. Why did everything have to be so rapid, these days? It certainly was not like the previous decade, when things had gone leisurely.
They stepped from the ramp, shook themselves, and were approached instantly by the building's polpol chief.
"We have a report on your man," the gray-uniformed officer told them.
"He hasn't taken off?" Fermeti said. "Thank God." He looked around.
"Over there," the officer said, pointing.
At a magazine rack, Poul Anderson was looking intently at the display. It took only a moment for the three Emigration Bureau officials to surround him.
"Oh, uh, hello," Anderson said. "While I was waiting for my ship I thought I'd take a look and see what's still in print."
Fermeti said, "Anderson, we require your unique abilities. I'm sorry, but we're taking you back to the Bureau."
All at once Anderson was gone. Soundlessly, he had ducked away; they saw his tall, angular form become smaller as he raced for the gate to the field proper.
Reluctantly, Fermeti reached within his coat and brought out a sleep-gun. "There's no other choice," he murmured, and squeezed.
The racing figure tumbled, rolled. Fermeti put the sleep-gun away and in a toneless voice said, "He'll recover. A skinned knee, nothing worse." He glanced at Gilly and Tozzo. "Recover at the Bureau, I mean."
Together, the three of them advanced toward the prone figure on the floor of the spaceport waiting room.
"You may return to your own time-continuum," Fermeti said quietly, "when you've given us the mass-restoration formula." He nodded, and a Bureau workman approached, carrying the ancient Royal typewriter.
Seated in the chair across from Fermeti in the Bureau's inner business office, Poul Anderson said, "I don't use a portable."
"You must cooperate," Fermeti informed him. "We have the scientific know-how to restore you to Karen; remember Karen and remember your newly-born daughter at the Congress in San Francisco's Sir Francis Drake Hotel. Without full cooperation from you, Anderson, there will be no cooperation from the Bureau. Surely, with your pre-cog ability you can see that."
After a pause Anderson said, "Urn, I can't work unless I have a pot of fresh coffee brewing around me at all times, somewhere."
Curtly, Fermeti signaled. "We'll obtain coffee beans for you," he declared. "But the brewing is up to you. We'll also supply a pot from the Smithsonian collection and there our responsibility ends."
Taking hold of the carriage of the typewriter, Anderson began to inspect it. "Red and black ribbon," he said. "I always use black. But I guess I can make do." He seemed a trifle sullen. Inserting a sheet of paper, he began to type. At the top of the page appeared the words:
Night Flight
--Poul Anderson
"You say If bought it?" he asked Fermeti.
"Yes," Fermeti replied tensely.
Anderson typed:
Difficulties at Outward, Incorporated had begun to nettle Edmond Fletcher. For one thing, an entire ship had disappeared, and although the individuals aboard were not personally known to him he felt a twinge of responsibility. Now, as he lathered himself with hormone-impregnated soap
"He starts at the beginning," Fermeti said bitingly. "Well, if there's no alternative we'll simply have to bear with him." Musingly, he murmured, "I wonder how long it takes... I wonder how fast he writes. As a pre-cog he can see what's coming next; it should help him to do it in a hurry." Or was that just wishful thinking?
"Have the coffee beans arrived yet?" Anderson asked, glancing up.
"Any time now," Fermeti said.
"I hope some of the beans are Colombian," Anderson said.
Long before the beans arrived the article was done.
Rising stiffly, uncoiling his lengthy limbs, Poul Anderson said, "I think you have what you want, there. The mass restoration formula is on typescript page 20."
Eagerly, Fermeti turned the pages. Yes, there it was; peering over his shoulder, Tozzo saw the paragraph:
If the ship followed a trajectory which would carry it into the star Proxima, it would, he realized, regain its mass through a process of leeching solar energy from the great star-furnace itself. Yes, it was Proxima itself which held the key to Torelli's problem, and now, after all this time, it had been solved. The simple formula revolved in his brain.
And, Tozzo saw, there lay the formula. As the article said, the mass would be regained from solar energy converted into matter, the ultimate source of power in the universe. The answer had stared them in the face all this time!
Their long struggle was over.
"And now," Poul Anderson said, "I'm free to go back to my own time?"
Fermeti said simply, "Yes."
"Wait," Tozzo said to his superior. "There's evidently something you don't understand." It was a section which he had read in the instruction manual attached to the time-dredge. He drew Fermeti to one side, where Anderson could not hear. "He can't be sent back to his own time with the knowledge he has now."
"What knowledge?" Fermeti inquired.
"That--well, I'm not certain. Something to do with our society, here. What I'm trying to tell you is this: the first rule of time travel, according to the manual, is don't change the past. In this situation just bringing Anderson here has changed the past merely by exposing him to our society."
Pondering, Fermeti said, "You may be correct. While he was in that gift shop he may have picked up some object which, taken back to his own time, might revolutionize their technology."
"Or at the magazine rack at the spaceport," Tozzo said. "Or on his trip between those two points. And--even the knowledge that he and his colleagues are pre-cogs"
"You're right," Fermeti said. "The memory of this trip must be wiped from his brain." He turned and walked slowly back to Poul Anderson. "Look here," he addressed him. "I'm sorry to tell you this, but everything that's happened to you must be wiped from your brain."
After a pause, Anderson said, "That's a shame. Sorry to hear that." He looked downcast. "But I'm not surprised," he murmured. He seemed philosophical about the whole affair. "It's generally handled this way."
Tozzo asked, "Where can this alteration of the memory cells of his brain be accomplished?"
"At the Department of Penology," Fermeti said. "Through the same channels we obtained the convicts." Pointing his sleep-gun at Poul Anderson he said, Come along with us. I regret this... but it has to be done."
VI
At the Department of Penology, painless electroshock removed from Poul Anderson's brain the precise cells in which his most recent memories were stored. Then, in a semi-conscious state, he was carried back into the time-dredge. A moment later he was on his trip back to the year 1954, to his own society and time. To the Sir Francis Drake Hotel in downtown San Francisco, California and his waiting wife and child.
When the time-dredge returned empty, Tozzo, Gilly and Fermeti breathed a sigh of relief and broke open a bottle of hundred-year-old Scotch which Fermeti had been saving. The mission had been successfully accomplished; now they could turn their attention back to the Project.
"Where's the manuscript that he wrote?" Fermeti said, putting down his glass to look all around his office.
There was no manuscript to be found. And, Tozzo noticed, the antique Koyal typewriter which they had brought from the Smithsonian--it was gone, too. But why?
Suddenly chill fear traveled up him. He understood.
"Good Lord," he said thickly. He put down his glass. "Somebody get a copy of the journal with his article in it. At once."
Fermeti said, "What is it, Aaron? Explain."
"When we removed his memory of what had happened we made it impossible for him to write the article for the journal," Tozzo said. "He must have based Night Flight on his experience with us, here." Snatching up the August 1955 copy of If he tur
ned to the table-of-contents page.
No article by Poul Anderson was listed. Instead, on page 78, he saw Philip K. Dick's The Mold of Yancy listed instead.
They had changed the past after all. And now the formula for their Project was gone--gone entirely.
"We shouldn't have tampered," Tozzo said in a hoarse voice. "We should never have brought him out of the past." He drank a little more of the century-old Scotch, his hands shaking.
"Brought who?" Gilly said, with a puzzled look.
"Don't you remember?" Tozzo stared at him, incredulous.
"What's this discussion about?" Fermeti said impatiently. "And what are you two doing in my office? You both should be busy at work." He saw the bottle of Scotch and blanched. "How'd that get open?"
His hands trembling, Tozzo turned the pages of the journal over and over again. Already, the memory was growing diffuse in his mind; he struggled in vain to hold onto it. They had brought someone from the past, a pre-cog, wasn't it? But who? A name, still in his mind but dimming with each passing moment... Anderson or Anderton, something like that. And in connection with the Bureau's interstellar mass-deprivation Project. Or was it?
Puzzled, Tozzo shook his head and said in bewilderment, "I have some peculiar words in my mind. Night Flight. Do either of you happen to know what it refers to?"
"Night Flight" Fermeti echoed. "No, it means nothing to me. I wonder, though--it certainly would be an effective name for our Project."
"Yes," Gilly agreed. "That must be what it refers to."
"But our Project is called Waterspider, isn't it?" Tozzo said. At least he thought it was. He blinked, trying to focus his faculties.