Again I stopped myself. I had to trust Callina; there was no other way. I went and stood before the screen.

Augmented by the screen, I could search, with telepathic forces augmented hundredfold, thousandfold, for such a one as we wanted. Of all the millions and billions of worlds in space and time, somewhere there was a mind such as we wanted, with a certain awareness—and a certain lackof awareness. With the screen we could attune that mind’s vibrations to thisparticular place in time and space; here, now, between the two poles of the screen. The space annihilated by the matrix, we could shift the—well, we call them energons, which is as good a name as any—shift the energons of that particular mind and the body behind it, and bring them here. My mind played with words like matter-transmitter, hyperspace, dimension-travel; but those were only words. The screen was the reality.

I dropped into one of the chairs before the screen, fiddling with a calibration which would allow me to match resonances between myself and Callina—more accurately, between her matrix and mine. I said, not looking up, “You’ll have to cut out the monitor screen, Callina,” and she nodded.

“There’s a bypass relay through Arilinn.” She touched controls and the monitor surface, a glassy screen—large, but half the size of the giant screen before me—blinked fitfully and went dark, shunting every monitored matrix on Darkover out of this relay. A grill crackled, sent out a tiny staccato signal; Callina listened attentively to no sound that I could hear—the message was not audible, and I was too preoccupied to merge into the relays. Callina listened for a moment, then spoke—aloud, perhaps as a courtesy to me, perhaps to focus her own thoughts for the relay.

“Yes, I know, Maruca, but we have cut out the main circuits here in Thendara; you’ll have to monitor from there.” Again the listening silence, then she rapped out, “Put up a third-level barrier around Thendara! That is a direct order from Comyn; observe and comply!” She turned away, sighing.

“That girl is the noisiesttelepath on the planet! Now everyone with a scrap of telepathy on the whole planet will know something is going on in Thendara tonight!”

We had had no choice; I said so. She took her own place before the screen, and I blanked my mind against it, ready for whatever she should demand of me. What sort of alien would suit us? But without volition, at least on my part, a pattern shaped itself on the screen. I saw the dim symbols in the moment before my optic nerve overloaded and I went out; then I was blind and deaf in that instant of overload which is always terrifying, however familiar it may become.

Gradually, without external senses, I found orientation within the screen. My mind, extended through astronomical distances, traversed in fractional seconds whole galaxies and parsecs of subjective spacetime. Vague touches of consciousness, fragments of thought, emotions that floated like shadows—the flotsam of the mental universe.

Then before I felt contact, I saw the white-hot flare in the screen. Somewhere another mind had fitted into the pattern which we had cast out like a net, and when we found the fitting intelligence it had been captured.

I swung out, bodiless, divided into a billion subjective fragments, extended over a vast gulf of spacetime. If anything happened, I would never get back to my body now, but would drift on the spacetime curve forever.

With infinite caution I poured myself into the alien mind. There was a short, terrible struggle. It was embedded-enlaced in mine. The world was a holocaust of molten-glass fire and color. The air writhed. The glow on the screen was a shadow, then solid, then a clearing darkness—

“Now!” I did not speak, simply flung the command at Callina, then light tore at my eyes, there was a ripping shock tearing at my brain, the floor seemed to rock and Callina was flung, reeling, into my arms as the energons seared the air and my brain.

Half stunned, but conscious, I saw that the screen was blank, the alien mind torn free of mine.

And in a crumpled heap on the floor, where she had fallen at the base of the screen, lay a slight, darkhaired woman.

I realized after a moment that I was still holding Callina in my arms; I let her go at the very instant that she moved to free herself of me. She knelt beside the strange woman, and I followed her.

“She’s not dead?”

“Of course not.” With the instincts of the Arilinn-trained, Callina was already feeling for a pulse, though her own was still thready and irregular. “But that—transition—nearly killed us, and we knew what to expect. What do you think it must have been like for her?”

Soft brown hair, falling across her face, hid her features. I brushed it gently back, and stopped, my hand still touching her cheek, in bewilderment.

“Linnell—” I whispered.

“No,” said Callina, “She sleeps in her own room…” but her voice faltered as she looked down at the girl. Then I knew who it must be; the young nurse I had seen on that dreadful night in the Terran hospital in Vainwal. Even knowing, as I did, what had happened, I thought my mind would give way. That transition had taken its toll of me too and I had to take a moment to quiet my own pulses and breathing.

“Avarra be merciful,” Callina whispered. “What have we done?”

Of course, I thought. Of course. Linnell was near to us both; sister, foster-sister. We had spoken with her just tonight. The pattern was at hand. Yet I still wondered, why Linnell, why not duplicate myself, or Callina?…

I tried to put it into simple words, more for myself than Callina.

“Cherilly’s Law. Everything in the universe—you, me, that chair, the drinking fountain in Port Chicago spaceport— everything exists in one, and only one, exact duplicate. Nothing is unique except for a matrix; even atoms have minute differences in the orbit of their electrons… there are equations to calculate the number of possible variations, but I’m not enough of a mathematician to calculate them. Jeff could probably reel them all off to you.”

“So this is… Linnell’s identical twin… ?”

“More alike than that; only once in a million times or so would a twin be the duplicate under Cherilly’s Law. This is her realtwin; same fingerprints, same retinal patterns and brainwave patterns, same betagraphs and blood type. She won’t be much like Linnell in personality, probably, because the duplicates of Linnell’s environmentare duplicated all over the Galaxy.” I pointed to the small scar beside her chin; turned over the limp wrist where the mark of Comyn was embedded in the flesh. “Probably a birthmark,” I said, “but it’s identical with Linnell’s Seal, see? Flesh and blood are identical; same blood type, and even her chromosomes, if you could monitor that deeply, would be identical with Linnell’s.”

Callina stared and stared. “She can live in this—this alien environment, then?”

“If she’s identical,” I said. “Her lungs breathe the same ratio of oxygen in the air as ours do, and her internal organs are adjusted to the same gravity.”

“Can you carry her?” Callina asked, “She’ll get a dreadful shock if she wakes up in this place.”

I grinned humorlessly. “She’ll get one anyhow.” But I managed to scoop her up one-handed; she was frail and light, like Linnell. Callina went ahead of me, pulled back curtains, showed me where to lay her down on a couch in a small bare room—I supposed the young men and women who worked in the relays sometimes took a nap here instead of returning to their own rooms. I covered her, for it was cold.

“I wonder where she comes from?” Callina murmured.

“From a world with about the same gravity as Darkover, which narrows it a little,” I evaded. I could not remember the nurse’s name, some barbaric Terran syllables. I wondered if she would recognize me. I should explain it all to Callina. But her face was lined with exhaustion, making her look gaunt, twice her age. “Let’s leave her to sleep off the shock— and get some sleep ourselves.”