"The facts we did gather, you see, indicated that whatever we were receiving must be definite signals, must originate within some sort of intelligence. Some intelligence, you see, that would know just when and where to send them. But there was the problem of distance. Just suppose for a moment that they were coming from the Great Nebula. It takes light almost a billion years to reach us from the Nebula. While it is very probable that the speed of light can be far exceeded, there is little reason to believe at present than anything could be so much faster than light that signaling could be practical across such enormous space. Unless, of course, the matter of time were mixed up a little, and when you get into that you have a problem that takes more than just a master mind. There was just one thing that would seem a probable answer… that if the signals were being sent from many light years distant, they were being routed through something other than all that space. Perhaps through another continuum of space-time, through what you might call, for the want of a better term, the fourth dimension."

"Doctor," said Herb, "you got me all balled up."

Dr. Kingsley's chuckle rumbled through the room.

"It had us that way, too," he said. "And then we figured maybe we were getting pure thought. Thought telepathed across the light years of unimaginable space. Just what the speed of thought would be no one could even guess. It might be instantaneous… it might be no faster than the speed of light… or any speed in between the two. But we do know one thing: that the signals we are receiving are the projection of thought. Whether they come straigh through space or whether they travel through some shortcut, through some manipulation of space-time frames, do not know and I probably will never know.

"It took us months to build that machine you saw in the other room. Briefly, it picks up the signals, translates them from the pure energy of thought into actual thought, into symbols our mind can read. We also developed a method of sending our own thoughts back, of communicating with whatever or whoever it is that is trying to talk with Pluto. So far we haven't been successful in getting an entire message across. However, apparently we have succeeded in advising whoever is sending out the messages that we are trying to answer, for recently the messages have changed, have a note of desperation, frantic command, almost a pleading quality."

He brushed his coat sleeve across his brow.

"It's all so confusing," he confessed.

"But," asked Herb, "why would anyone send messages to Pluto? Until men came here, there was no life on the planet. Just a barren planet, without any atmosphere, too cold for anything to live. The tail end of creation."

Kingsley stared solemnly at Herb.

"Young man," he said, "we must never take anything for granted. How are we to say there never was life or intelligence on Pluto? How do we know that a great civilization might not have risen and flourished here aeons ago? How do we know that an expeditionary force from some far-distant star might not have come here and colonized this outer planet many years ago?"

"It don't sound reasonable," said Herb.

Kingsley gestured impatiently.

"Neither do these signals sound reasonable," he rumbled. "But there they are. I've thought about the things you mention. I am damned with an imagination, something no scientist should have. A scientist should just plug along, applying this bit of knowledge to that bit of knowledge to arrive at something new. He should leave the imagination to the philosophers. But I'm not that way. I try to imagine what might have happened or what is going to happen. I've imagined a mother planet groping out across all space, trying to get in touch with some long-lost colony here on Pluto. I've imagined someone trying to re-establish communication with the people who lived here millions of years ago. But it doesn't get me anywhere."

Gary filled and lit his pipe, frowning down at the glowing tobacco. Voices in space again. Voices talking across the void. Saying things to rack the human soul.

"Doctor," he said, "you aren't the only one who has heard thought from outer space."

Kingsley swung on him, almost belligerently. "Who else?" he demanded.

"Miss Martin," said Gary quietly, puffing at his pipe. "You haven't heard Miss Martin's story yet. I have a hunch that she can help you out."

"How's that?" rumbled the scientist.

"Well, you see," said Gary, softly, "she's just passed through a thousand years of mind training. She's thought without ceasing for almost ten centuries."

Kingsley's face drooped in amazement.

"That's impossible," he said.

Gary shook his head. "Not impossible at all. Not with suspended animation."

Kingsley opened his mouth to object again, but Gary hurried on. "Doctor," he asked, "do you remember the historical account of the Caroline Martin who refused to give an invention to the military board during the Jovian war?"

"Why, yes," said Kingsley. "Scientists have speculated for many years on just what it was she found —»

He started out of his chair.

"Caroline Martin!" he shouted. He looked at the girl.

"Your name is Caroline Martin, too," he whispered huskily.

Gary nodded. "Doctor, this is the woman who refused to give up that secret a thousand years ago."

CHAPTER Five

DR. KINGSLEY glanced at his watch.

"It's almost time for the signals to begin," he said. "In another few minutes we will be swinging around to face the Great Nebula. If you looked out you would see it over the horizon now."

Caroline Martin sat in the chair before the thought machine, the domed helmet settled on her head. All eyes in the room were glued on the tiny light atop the mechanism. When the signals started coming that light would blink its bright-red eye.

"Lord, it's uncanny," whispered Tommy Evans. He brushed at his face with his hand.

Gary watched the girl. Sitting there so straight, like a queen with a crown upon her head. Sitting there, waiting, waiting to hear something that spoke across a gulf that took light many years to span.

Brain sharpened by a thousand years of thought, a woman who was schooled in hard and simple logic. She had thought of many things out in the shell, she said, had set up problems and had worked them out. What were those problems she had thought about? What were the mysteries she had solved? She was a young, rather sweet-faced kid, who ought to like a good game of tennis, or a dance and she'd thought a thousand years.

Then the light began to blink and Gary saw Caroline lean forward, heard the breath catch sharply in her throat. The pencil she had poised above the pad dropped from her fingers and fell onto the floor.

Heavy silence engulfed the room, broken only by the whistling of the breath in Kingsley's nostrils. He whispered to Gary: "She understands! She understands…"

Gary gestured him to silence.

The red light blinked out and Caroline swung around slowly in the chair. Her eyes were wide and for a moment she seemed unable to give voice to the words she sought.