When Gordon awoke in the morning, the whole incredible thing came back to him with a rush.

“Was it a dream?” he asked himself wonderingly. “Zarth Arn said it would seem like one. Of course, a dream-person would say that.”

Gordon still could not make up his mind whether or not it had been real, by the time he went to work.

Never had the insurance office looked so utterly drab and stifling as on that long day. Never had the petty routine of his duties seemed so barren and monotonous.

And all through the day, Gordon found himself dreaming wild visions of the splendor and magic wonder of great star-kingdoms two hundred thousand years in the future, of worlds new, strange, luring.

By the end of the day, his decision was reached. If this incredible thing was really true, he was going to do what Zarth Arn asked.

He felt a little foolish as he stopped on his way home and bought childrens' picture-books, language texts, and phonograph records intended for the teaching of English.

But that night, Gordon went early to bed. Strung to the highest pitch of feverish excitement, he awaited for Zarth Arn's call.

It did not come. For Gordon could not even begin to fall asleep. He was too tautly excited even to doze.

For hours, he tossed and turned. It was nearly dawn by the time he fell into a troubled doze.

Then, at once, the clear mental voice of Zarth Arn came into his mind.

“At last I can contact you. Now tell me, John Gordon, what is your decision?”

“I'll do it, Zarth Arn,” answered Gordon. “But I must do it at once. For if I spend many more days thinking about the thing, I'll believe myself going crazy over a dream.”

“It can be done at once,” was the eager reply. “Vel Quen and I have our apparatus ready. You will inhabit my body for six weeks. At the end of that time, I will be ready for the re-exchange.”

Zarth Arn continued rapidly. “You must first make me one promise. Nobody in this age but Vel Quen will know of this mind-exchange. You must tell no one here in my time that you are a stranger in my body. To do so might bring disaster on us both.”

“I promise,” Gordon replied quickly. He added troubledly, “You'll be careful with my body, won't you?”

“You have my word,” was the answer of Zarth Arn. “Now relax yourself so that your mind will offer no resistance to the force that draws it across the time-dimension.”

That was easier to say than to do. Relaxing was not what a man felt like doing when his mind was about to be drawn from his body.

But Gordon tried to obey, to sink deeper into the dozing state.

Suddenly he felt a strange, uncanny tugging inside his brain. It was not a physical sensation, but it gave a feeling of magnetic power.

Fear such as John Gordon had never before experienced shrieked in his mind as he felt himself rushing into unplumbed darkness.

CONSCIOUSNESS came back slowly to Gordon. He found himself lying on a high table in a room of brilliant sunlight.

For some moments he lay looking up dazedly, feeling a terrible weakness and shakiness. Right over his head, as though just swung back, was a curious apparatus like a silver cap with many wires.

Then a face bent down into his view. It was the wrinkled face of an old, white-haired man. But the excitement he evidently felt made his blue eyes youthfully eager.

He spoke to Gordon in a voice shrill with excitement. But he spoke in a language that was almost entirely unfamiliar.

“I can't understand you,” Gordon said helplessly.

The other pointed to himself and spoke again. “Vel Quen,” he said.

Vel Quen? Gordon remembered now. Zarth Arn had said that was the name of his scientific colleague in the future.

The future? Then the two scientists had effected that incredible exchange of minds and bodies across the abyss of time?

With sudden wild excitement, Gordon tried to sit up. He couldn't do it. He was still too weak, and slipped back.

But he had got a glimpse of his own body as he sat up, and the sight had stunned him.

It wasn't his body. It was not John Gordon's stocky, muscular figure. This was a taller, slimmer body he now inhabited, one dressed in silky white sleeveless shirt and trousers, and sandals.

“Zarth Arn's body!” husked Gordon. “And back in my own time, Zarth Arn is awaking in mine.”

Old Vel Quen apparently recognized the name he spoke. The old scientist nodded quickly.

“Zarth Arn-John Gordon,” he said, pointing at him.

The exchange had worked. He had crossed two thousand centuries and was now in another man's body!

It didn't feel any different. Gordon tried moving his hands and feet. Every muscle responded perfectly. Yet his hair still bristled from the ghastly strangeness of it. He had a hysterical nostalgia for his own body.

Vel Quen seemed to understand his feelings. The old man patted his shoulder reassuringly, then offered him a crystal beaker filled with foaming red liquid. Gordon drank it, and began to feel stronger.

The old scientist helped him get up from the table, and steadied him as he stood looking wonderingly around the room.

Brilliant sunlight poured through tall windows that filled all eight sides of the octagonal chamber. The light flashed and glittered off machines and instruments and racks of queer metal spools. Gordon was no scientist, and all this science of the future baffled him.

Vel Quen led him toward a corner in which there was a tall mirror. He stood transfixed the moment he caught a glimpse of himself in the glass.

“So this is what I look like now!” Gordon whispered, staring wildly at his own image.

His figure was now that of a tall, black-haired young man of well over six feet. The face was dark, aquiline and rather handsome, with serious dark eyes. It was altogether different from John Gordon's own square, tanned face.

He saw that he was wearing snug fitting shirt and trousers. Vel Quen threw a long, silky white cloak around his shoulders. The old scientist himself was similarly attired.

He gestured to Gordon that he must rest. But weak as Gordon felt, he couldn't without first looking out at this unknown world of the far future.

He stumbled to one of the windows. He expected to look forth on wondrous vistas of super-modern cities, marvelous metropoli of the star-conquering civilization. But Gordon was disappointed.

Before him lay a scene of wild, forbidding natural grandeur. This octagonal chamber was the upper floor of a massive little cement tower which was perched on a small plateau at the edge of a sheer precipice.

Stupendous mountain peaks crowned with glittering white snow rose in the bright sunlight. From them and from the tower, dark and awesome defiles dropped for thousands of feet. There was not another building in sight. It looked much like the Himalayas of his own time.

Weakness made John Gordon sway dizzily. Vel Quen hastily led him out of the tower-room and down to a small bedroom on the floor below. He stretched on a soft couch and was almost instantly asleep.

When Gordon awoke, it was another day. Vel Quen came in and greeted him, then checked his pulse and respiration. The old scientist smiled reassuringly, and brought him some food.

There was a thick, sweet, chocolate colored drink, some fruit, some wafers like dry biscuits. It was all evidently charged with nutritional elements, for Gordon's hunger vanished after the slight meal.

Then Vel Quen began to teach him his language. The old man used a boxlike little apparatus which produced realistic stereoscopic images, carefully naming each object or scene be exhibited.

Gordon spent a week in this task, not going outside the tower. He picked up the language with astonishing quickness, partly because of Vel Quen's scientific teaching and partly because it was based on his own English. Two thousand centuries had greatly enlarged and changed its vocabulary, but it was not like a completely alien tongue.