The thought was simply this: That he would ruin Eternity, if he had to.

The worst of it was that he knew he had the power to do it.

Harlan stood at the gateway to Time and thought of himself in new ways. It had been very simple once. There were such things as ideals, or at least catchwords, to live by and for. Every stage of an Eternal's life had a reason. How did "Basic Principles" start?

"The life of an Eternal may be divided into four parts…"

It all worked out neatly, yet it had all changed for him, and what was broken could not be made whole again.

Yet he had gone faithfully through each of the four parts of an Eternal's life. First, there was the period of fifteen years in which he was not an Eternal at all, but only an inhabitant of Time. Only a human being out of Time, a Timer, could become an Eternal; no one could be born into the position.

At the age of fifteen he was chosen by a careful process of elimination and winnowing, the nature of which he had no conception.of at the time. He was taken beyond the veil of Eternity after a last agonized farewell to his family. (Even then it was made clear to him that whatever else happened he would never return. The true reason for that he was not to learn till long afterward.)

Once within Eternity, he spent ten years in school as a Cub, and then graduated to enter his third period as Observer. It was only after that that he became a Specialist and a true Eternal. The fourth and last part of the Eternal's life: Timer, Cub, Observer and Specialist.

He, Harlan, had gone through it all so neatly. He might say, successfully.

He could remember, so clearly, the moment that Cubhood was done, the moment they became independent members of Eternity, the moment when, even though un-Specialized, they still rated the legal title of "Eternal."

He could remember it. School done, Cubhood over, he was standing with the five who completed training with him, hands clasped in the small of his back, legs a trifle apart, eyes front, listening.

Educator Yarrow was at a desk talking to them. Harlan could remember Yarrow well: a small, intense man, with ruddy hair in disarray, freckled forearms, and a look of loss in his eyes. (It wasn't uncommon, this look of loss in the eyes of an Eternal-the loss of home and roots, the unadmitted and unadmittable longing for the one Century he could never see.)

Harlan could not remember Yarrow's exact words, of course, but the substance of it remained sharp.

Yarrow said, in substance, "You will be Observers now. It isn't a highly regarded position. Specialists look upon it as a boy's job. Maybe you Eternals" (he deliberately paused after that word to give each man a chance to straighten his back and brighten at the glory of it) "think so too. If so, you are fools who don't deserve to be Observers.

"The Computers would have no Computing to do, Life-Plotters no lives to Plot, Sociologists no societies to profile; none of the Specialists would have anything to do, if it weren't for the Observer. I know you've heard this said before, but I want you to be very firm and clear in your mind about it.

"It will be you youngsters who will go out into Time, under the most strenuous conditions, to bring back facts. Cold, objective facts uncolored by your own opinions and likings, you understand. Facts accurate enough to be fed into Computing machines. Facts definite enough to make the social equations stand up. Facts honest enough to form a basis for Reality Changes.

"And remember this, too. Your period as Observer is not something to get through with as quickly and as unobtrusively as possible. It is as an Observer that you will make your mark. Not what you did in school, but what you will do as an Observer will determine your Specialty and how high you will rise in it. This will be your post-graduate course, Eternals, and failure in it, even small failure, will put you into Maintenance no matter how brilliant your potentialities now seem. That is all."

He shook hands with each of them, and Harlan, grave, dedicated, proud in his belief that the privileges of being an Eternal contained its greatest privilege in the assumption of responsibility for the happiness of all the human beings who were or ever would be within the reach of Eternity, was deep in self-awe.

Harlan's first assignments were small and under close direction, but he sharpened his ability on the honing strap of experience in a dozen Centuries through a dozen Reality Changes.

In his fifth year as Observer he was given a Senior's rating in the field and assigned to the 482nd. For the first time he would be working unsupervised, and knowledge of that fact robbed him of some of his self-assurance when he first reported to the Computer in charge of the Section.

That was Assistant Computer Hobbe Finge, whose pursed, suspicious mouth and frowning eyes seemed ludicrous in such a face as his. He had a round button of a nose, two larger buttons of cheeks. He needed only a touch of red and a fringe of white hair to be converted into the picture of the Primitive myth of St. Nicholas.

(-or Santa Claus or Kriss Kringle. Harlan knew all three names. He doubted if one Eternal out of a hundred thousand had heard of any one of them. Harlan took a secret, shamefaced pride in this sort of arcane knowledge. From his earliest days in school he had ridden the hobbyhorse of Primitive history, and Educator Yarrow had encouraged it. Harlan had grown actually fond of those odd, perverted Centuries that lay, not only before the beginning of Eternity in the 27th, but even before the invention of the Temporal Field, itself, in the 24th. He had used old books and periodicals in his studies. He had even traveled far downwhen to the earliest Centuries of Eternity, when he could get permission, to consult better sources. For over fifteen years he had managed to collect a remarkable library of his own, almost all in print-on-paper. There was a volume by a man called H. G. Wells, another by a man named W. Shakespeare, some tattered histories. Best of all there was a complete set of bound volumes of a Primitive news weekly that took up inordinate space but that he could not, out of sentiment, bear to reduce to micro-film.

Occasionally he would lose himself in a world where life was life and death, death; where a man made his decisions irrevocably; where evil could not be prevented, nor good promoted, and the Battle of Waterloo, having been lost, was really lost for good and all. There was even a scrap of poetry he treasured which stated that a moving finger having once written could never be lured back to unwrite.

And then it was difficult, almost a shock, to return his thoughts to Eternity, and to a universe where Reality was something flexible and evanescent, something men such as himself could hold in the palms of their hands and shake into better shape.)

The illusion of St. Nicholas shattered when Hobbe Finge spoke to him in a brisk, matter-of-fact way. "You can start in tomorrow with a routine screening of current. Reality. I want it good, thorough, and to the point. There will be xio slackness permitted. Your first spatio-temporal chart will be ready for you tomorrow morning. Got it?"

"Yes, Computer," said Harlan. He decided as early as that that he and Assistant Computer Hobbe Finge would not get along, and he regretted it.

The next morning Harlan got his chart in intricately punched patterns as they emerged from the Computaplex. He used a pocket decoder to translate them into Standard Intertemporal in his anxiety to make not even the smallest mistake at the very beginning. Of course, he had reached the stage where he could read the perforations direct.

The chart told him where and when in the world of the 482nd Century he might go and where he might not; what he could do and what be could not; what he must avoid at all costs. His presence must impinge only upon those places and times where it would not endanger Reality.