"We're not in danger here," said Drengo, at his elbow. "No fire nor bomb can reach us here--that is the result of your mighty Atlantic Coast Barrier. Nothing more. It never was perfected in time, before the great Eastern Invasion and the second Atomic War. That was due to occur three years after the time-area where we visited. We were trying to stem it, to turn it aside. We don't know yet whether we succeeded or not."
He turned to the tall man standing at the door. "Markson, all the calculations are prepared. The Calc is evaluating the data against the Equation now, figuring all the variables. If our work did any good, we should know it soon." He sighed and pointed to the Palace. "But our fine Dictator is still alive, and the attack on Mars should be starting any minute--If we didn't succeed, nothing in all Time will stop him."
Roger lit a cigarette, his eyes questioning Drengo. "Dictator?"
Drengo sat down and stretched his legs. "The Dictator appeared four years ago, a nobody, a man from the masses of people on the planet. He rose into public favor like a sky-rocket, a remarkable man, an amazing man--a man who could talk to you, and control your thoughts in a single interview. There has never been a man with such personal magnetism and power, Roger, in all the history of Earth. A man who raised himself from nothing into absolute Dictatorship, and has handled the world according to his whim ever since.
"He is only a young man, Roger, just 32 years of age, but an irresistible man who can win anything from anybody. He writhed into the presidency first, and then deliberately set about rearranging the government to suit himself. And the people let him get away with it, followed him like sheep. And then he was Dictator, and he began turning the social and economic balance of the planet into a whirlwind. And then came Mars."
Martin stretched again, and lit a cigarette, his thin face grave in the darkened room. "The first landing was thirty years ago, and the possibilities for rich and peaceful commerce between Earth and Mars were clear from the first. Mars had what Earth lacked: the true civilization, the polished culture, the lasting socio-economic balance, the permanent peace. Mars could have taught us so much. She could have guided us out of the mire of war and hatred that we have been wallowing in for centuries. But the Dictator put an end to those possibilities." Drengo shrugged. "He was convinced that the Martians were weak, backward, decadent. He saw their uranium, their gold, their jewelry, their labor--and started on a vast impossible imperialism. If he had had his way, he would have stripped the planet in three years, but the Martians fought against us, turned from peace to suspicion, and finally to open revolt. And the Dictator could not see. He mobilized Earth for total war against Mars, draining our resources, decimating our population, building rockets, bombs, guns--" He stopped for a moment, breathing deeply. "But the Dictator didn't know what he was doing. He had never been on Mars. He has never seen Martians. He had no idea what they think, what they are capable of doing. He doesn't know what we know--that the Martians will win. He doesn't realize that the Martians can carry out a war for years without shaking their economy one iota, while he has drained our planet to such a degree that a war of more than two or three months will break us in half. He doesn't know that Mars can win, and that the Earth can't--"
Roger walked across the room, thoughtfully, his mind fitting pieces into place. "But where do I come in? David--Ann--I don't understand--"
Drengo looked Roger straight in the eye. "The Dictator's name," he said, "is Farrel Strang."
Roger stopped still. "Strang?" he echoed.
"Your son, Roger. Yours and Ann's."
"But--you said the Dictator was only 32--" Roger trailed off, regarding Ann in amazement.
Martin smiled. "People don't grow old so quickly nowadays," he said.
"You are 57 years old, Roger. Ann is 53." He leaned back in his chair, his gaunt smile fading. "The Dictator has not been without opposition.
You, his parents, opposed him at the very start, and he cast you off.
People wiser than the crowds were able to rebuff his powerful personal appeal, to see through the robe of glory he had wrapped around himself. He has opposition, but he has built himself an impregnable fortress, and dealt swift death to any persons suspected of treason. A few have escaped--scientists, technologists, sociologists, physicists.
The work of one group of men gave us a weapon which we hoped to use to destroy the Dictator. We found a way to move back in Time. We could leave the normal time-stream and move to any area of past time. So four of us went back, searching for the core of the economic and social upheaval on Earth, and trying to destroy the Dictator before he was born. Given Time travel, it should have been possible. So we went back--myself, John Morrel, Ann Strang, and you."
Roger shook his head, a horrible thought forming in his mind. "You were trying to kill David--my son--" he stopped short. "David _couldn't_ have been my son!" He whirled on Martin Drengo. "_Who was that boy?_"
Martin looked away then, his face white. "The boy was your father," he said.
The drone of the jet bombers came again, whining into the still room.
Roger Strang stood very still, staring at the gaunt man. Slowly the puzzle was beginning to fit together, and horror filtered into his mind. "My father--" he said. "Only twelve years old, but he was to be my father." He stared helplessly at the group in the room. "You were trying--to kill him!"
Martin Drengo stood up, his lean face grave. "We were faced with a terrific problem. Once we returned to a time-area, we had no way of knowing to what extent we could effect people and events that had already happened. We had to go back, to fit in, somehow, in an area where we never had been, to _make_ things happen that had never happened before. We knew that if there was any way of doing it, we had to destroy Farrel Strang. But the patterns of history which had allowed him to rise had to be altered, too; destroying the man would not have been enough. So we tried to destroy him in the time-area where the leading time-patterns of _our_ time had been formed. We had to kill his grandfather."
Roger shivered. "But if you had killed David--what would have happened _to me_?"
"Presumably the same thing that would have happened to the Dictator.
In theory, _if we had succeeded_ in killing your father, David, both you and the Dictator would have ceased to exist." Drengo took a deep breath. "The idea was yours, Roger. You knew the terrible damage your son was doing as Dictator. It was a last resort, and Ann and John and I pleaded with you to reconsider. But it was the obvious step."
Ann walked over to Roger, her face pale. "You insisted, Roger. So we did what we could to make it easy. We used the Dictator's favorite trick--a psycho-purge--to clear your mind of all conscious and subconscious memory of your true origin and environment, replacing it with a history and memory of the past-time area where we were going.
We chose the contact-time carefully, so that we appeared in New York in the confusion of the bombing of 2078, making sure that your records would stand up under all but the closest examination. From then on, when Martin carried you out from the fire, you stored your own memory of that time-area and became a legitimate member of that society."
"But how could we pose as David's _parents_, if he was my father?"
Ann smiled. "Both David's parents were killed in the New York bombing; we knew that David survived, and we knew where he could be found.
There was a close physical resemblance between you and the boy, though actually the resemblance was backwards, and he accepted you as a foster-father without question. With you equipped with a complete memory of your marriage to me in that time, of David's birth, and of your own history before and after the bombing of New York, you fit in well and played the part to perfection. Also, you acted as a control, to guide us, since you had no conscious knowledge beyond that time-area. Martin and Morrel were to be the assassins, the Intruders, and I was to keep tabs on you--"
"And the success of the attempt?"
Ann's face fell. "We don't know yet. We don't know what we accomplished, whether we stemmed the war or not--"
The tall man who had stepped into the room moved forward and threw a sheaf of papers on the floor, his face heavy with anger, his voice hoarse. "Yes, I'm afraid we do know," he said bitterly.
Martin Drengo whirled on him, his face white. "What do you mean, Markson?"
The tall man sank down in a chair tiredly. "We've lost, Martin. We don't need these calculations to tell. The word was just broadcast on the telecast. Farrel Strang's armada has just begun its attack on Mars--"
For a moment the distant bombing was the only sound in the room. Then Martin Drengo said, "So he gave the order. And we've lost."
"We only had a theory to work on," said Morrel, staring gloomily at the curved window. "A theory and an equation. The theory said that a man returning through time could alter the social and technological trends of the people and times to which he returned, in order to change history that was already past. The theory said that if we could turn the social patterns and technological trends just slightly away from what they were, we could alter the entire makeup of society in our own time. And the Equation was the tool, the final check on any change. The Equation which evaluates the sum of social, psychological and energy factors in any situation, any city or nation or human society. The Equation has been proven, checked time and time again, but the theory didn't fit it. The theory was wrong."
Roger Strang sat up, suddenly alert. "That boy," he said, his voice sharp. "You nearly made a sieve of him, trying to shoot him. Why didn't he die?"
"Because he was on a high-order variable. Picture it this way: From any point in time, the possible future occurrences could be seen as vectors, an infinite number of possible vectors. Every activity that makes an alteration, or has any broad effect on the future is a high-order variable, but many activities have no grave implications for future time, and could be considered unimportant, or low-order variables. If a man turns a corner and sees something that stimulates him into writing a world-shaking manifesto, the high-order variable would have started when he decided to turn the corner instead of going the other way. But if he took one way home instead of another, and nothing of importance occurred as a result of the decision, a low-order variable would be set up.
"We found that the theory of alterations held quite well, for low-order variables. Wherever we appeared, whatever we did, we set up a definite friction in the normal time-stream, a distortion, like pulling a taut rubber band out. And we could produce changes--on low-order variables. But the elasticity of the distortion was so great as to warp the change back into the time-stream without causing any lasting alteration. When it came to high-order changes, _we simply couldn't make any_. We tried putting wrong data into the machines that were calculating specifications for the Barrier, and the false data went in, but the answers that came out were answers that _should_ have appeared with the _right_ data. We tried to commit a murder, to kill David Strang, and try as we would we couldn't do it. Because it would have altered a high-order variable, and they simply _wouldn't be altered_!"
"But you, Morrel," Roger exclaimed. "How about you? You were top man in the Barrier Base Security office. You must have made an impression."
Morrel smiled tiredly. "I really thought I had, time after time. I would start off a series of circumstances that should have had a grave alterative effect, and it would look for awhile as if a long-range change was going to be affected--and then it would straighten itself out again, with no important change occurring. It was maddening. We worked for five years trying to make even a small alteration--and brought back our data--" He pointed to the papers on the floor. "There are the calculations, applied on the Equation. Meaningless. We accomplished nothing. And the Dictator is still there."
Drengo slumped in his chair. "And he's started the war. The real attack. This bombardment outside is nothing. There are fifteen squadrons of space-destroyers already unloading atomic bombs on the surface of Mars, and that's the end, for us. Farrel Strang has started a war he can never finish--"
Roger Strang turned sharply to Drengo. "This Dictator," he said.
"Where is he? Why can't he be reached now, and destroyed?"
"The Barrier. He can't be touched in the Palace. He has all his offices there, all his controls, and he won't let anyone in since the attempted assassination three months ago. He's safe there, and we can't touch him."
Roger scowled at the control panel on the wall. "How does this time-portal work?" he asked. "You say it can take us back--_why not forward?_"
"No good. The nature of Time itself makes that impossible. At the present instant of Time, everything that has happened has happened.
The three-dimensional world in which we live has passed through the fourth temporal dimension, and nothing can alter it. But at this instant there are an infinite number of things that could happen next.
The future is an infinite series of variables, and there's no conceivable way to predict which variable will actually be true."
Roger Strang sat up straight, staring at Drengo. "Will that portal work both ways?" he asked tensely.
Drengo stared at him blankly. "You mean, can it be reverse-wired? I suppose so. But--anyone trying to move into the future would necessarily become an _infinity_ of people--he couldn't maintain his identity, because he'd have to have a body in every one of an infinite number of places he might be--"
"--_until the normal time stream caught up with him in the future!_ And then he'd be in whatever place he fit!" Roger's voice rose excitedly. "Martin, can't you see the implications? Send me ahead--just a little ahead, an hour or so--and let me go into the Palace. If I moved my consciousness to the place where the Palace should be, where the Dictator should be, then when normal time caught up with me, _I could kill him_!"
Drengo was on his feet, staring at Roger with rising excitement.
Suddenly he glanced at his watch. "By God!" he muttered. "_Maybe you could_--"