An ink spot on the handkerchief becomes the Time Gate. By folding the handkerchief that spot may be superposed on any other spot on the silk. Press the two spots together between thumb and forefinger; the controls are set, the Time Gate is open, a microscopic inhabitant of this piece of silk may crawl from one fold to the other without traversing any other part of the cloth.

The model is imperfect; the picture is static—but a physical picture is necessarily limited by the sensory experience of the person visualizing it.

He could not make up his mind whether or not the concept of folding the four-dimensional continuum—three of space, one of time—back on itself so that the Gate was "open" required the concept of higher dimen­sions through which to fold it. It seemed so, yet it might simply be an intellectual shortcoming of the human mind. Nothing but empty space was required for the "folding," but "empty space" was itself a term totally lacking in meaning—he was enough of a mathematician to know that.

If higher dimensions were required to "hold" a four-dimensional con­tinuum, then the number of dimensions of space and of time were neces­sarily infinite; each order requires the next higher order to maintain it.

But "infinite" was another meaningless term. "Open series" was a little better, but not much.

Another consideration forced him to conclude that there was probably at least one more dimension than the four his senses could perceive—the Time Gate itself. He became quite skilled in handling its controls, but he never acquired the foggiest notion of how it worked, or how it had been built. It seemed to him that the creatures who built it must necessarily have been able to stand outside the limits that confined him in order to anchor the Gate to the structure of space time. The concept escaped him.

He suspected that the controls he saw were simply the ones that stuck through into the space he knew. The very palace itself might be no more than a three-dimensional section of a more involved structure. Such a condition would help to explain the otherwise inexplicable nature of its architecture.

He became possessed of an overpowering desire to know more about these strange creatures, the "High Ones," who had come and ruled the human race and built this palace and this Gate, and gone away again— and in whose backwash he had been flung out of his setting some thirty millennia. To the human race they were no more than a sacred myth, a contradictory mass of tradition. No picture of them remained, no trace of their writing, nothing of their works save the High Palace of Norkaal and the Gate. And a sense of irreparable loss in the hearts of the race they had ruled, a loss expressed by their own term for themselves—the For­saken Ones.

With controls and speculum he hunted back through time, seeking the Builders. It was slow work, as he had found before. A passing shadow, a tedious retracing—and failure.

Once he was sure that he had seen such a shadow in the speculum. He set the controls back far enough to be sure that he had repassed it, armed himself with food and drink and waited.

He waited three weeks.

The shadow might have passed during the hours he was forced to take out for sleep. But he felt sure that he was in the right period; he kept up the vigil.

He saw it.

It was moving toward the Gate.

When he pulled himself together he was halfway down the passageway leading away from the hall. He realized that he had been screaming. He still had an attack of the shakes.

Somewhat later he forced himself to return to the hall, and, with eyes averted, enter the control booth and return the spheres to zero. He backed out hastily and left the hall for his apartment. He did not touch the controls or enter the hall for more than two years.

It had not been fear of physical menace that had shaken his reason, nor the appearance of the creature—he could recall nothing of how it looked. It had been a feeling of sadness infinitely compounded which had flooded through him at the instant, a sense of tragedy, of grief insupportable and unescapable, of infinite weariness. He had been flicked with emotions many times too strong for his spiritual fiber and which he was no more fitted to experience than an oyster is to play a violin.

He felt that he had learned all about the High Ones a man could learn and still endure. He was no longer curious. The shadow of that vicarious emotion ruined his sleep, brought him sweating out of dreams.

One other problem bothered him—the problem of himself and his meanders through time. It still worried him that he had met himself coming back, so to speak, had talked with himself, fought with himself.

Which one was himself?

He was all of them, he knew, for he remembered being each one. How about the times when there had been more than one present?

By sheer necessity he was forced to expand the principle of nonidentity—"Nothing is identical with anything else, not even with itself"—to include the ego. In a four-dimensional continuum each event is an abso­lute individual, it has its space coordinates and its date. The Bob Wilson he was right now was not the Bob Wilson he had been ten minutes ago. Each was a discrete section of a four-dimensional process. One resembled the other in many particulars, as one slice of bread resembles the slice next to it. But they were not the same Bob Wilson—they differed by a length of time.

When he had doubled back on himself, the difference had become apparent, for the separation was now in space rather than in time, and he happened to be so equipped as to be able to see a space length, whereas he could only remember a time difference. Thinking back he could remember a great many different Bob Wilsons, baby, small child, adoles­cent, young man. They were all different—he knew that. The only thing that bound them together into a feeling of identity was continuity of memory.

And that was the same thing that bound together the three—no, four, Bob Wilsons on a certain crowded afternoon, a memory track that ran through all of them. The only thing about it that remained remarkable was time travel itself.

And a few other little items—the nature of "free will," the problem of entropy, the law of the conservation of energy and mass. The last two, he now realized, needed to be extended or generalized to include the cases in which the Gate, or something like it, permitted a leak of mass, energy or entropy from one neighborhood in the continuum to another. They were otherwise unchanged and valid. Free will was another matter. It could not be laughed off, because it could be directly experienced—yet his own free will had worked to create the same scene over and over again. Apparently human will must be considered as one of the, factors which make up the processes in the continuum—"free" to the ego, mechanistic from the outside.

And yet his last act of evading Diktor had apparently changed the course of events. He was here and running the country, had been for many years, but Diktor had not showed up. Could it be that each act of "true" free will created a new and different future? Many philosophers had thought so.

This future appeared to have no such person as Diktor—the Diktor— in it, anywhere or anywhen.

As the end of his first ten years in the future approached, he became more and more nervous, less and less certain of his opinion. Damnation, he thought, if Diktor is going to show up it was high time that he did so. He was anxious to come to grips with him, establish which was to be boss.

He had agents posted throughout the country of the Forsaken Ones with instructions to arrest any man with hair on his face and fetch him forthwith to the palace. The Hall of the Gate he watched himself.

He tried fishing the future for Diktor, but had no significant luck. He thrice located a shadow and tracked it down; each time it was himself. From tedium and partly from curiosity he attempted to see the other end