All right, he said after another pause. But be careful, okay?

Sure. Enjoy your flight, and I'll talk to you later.

Yeah. Take care.

I sat where I was for a long time afterwards, my book lying ignored on my lap. Once again I felt torn between my natural desire for caution and my almost suffocating urgency to possess a telepath shield.

Colleen was practically within my grasp-how could I permit anything to get in the way of that? Besides, what earthly use would a telepath shield-or anything else Green could make in my basement-be to a normal person? A defense against the highly unlikely possibility of one of us eavesdropping on a private conversation? Ridiculous, when thirty feet of distance would achieve the same end. No-I had to be reading Green wrong... and I didn't need to be reminded that Nelson had had a strong touch of paranoia.

Nevertheless, that evening I went out and bought a burglar alarm, and by the time I went to bed I had it rigged so that anyone entering or leaving my basement would trigger a light and quiet buzzer in my second-floor study. Now, whenever Green tried to leave I would know in time to get within telepathy range of him before he got out of the house. A rather simple precaution, to be sure-but then, I wasn't really expecting any trouble.

The days lengthened into weeks, as days have a way of doing, and progress on the shield remained depressingly slow. Green's idea about reversing the biases hadn't panned out, and he'd been forced to seek out new approaches. Fortunately, he didn't get discouraged as easily as I might have, his failures merely spurring him to stronger efforts. He began to spend more and more time at my house, sometimes arriving while I was still eating dinner and not leaving until after midnight. What made his single-mindedness all the more astonishing was the fact that he still felt acutely uncomfortable around me, avoiding close contact and sometimes even going so far as to fill his mind with technical thoughts to try to forget I was within range. Apparently he was simply the type who enjoyed a challenge for its own sake.

What with all this companionship therapy taking up a lot of my attention, it was early October before I finally noticed something was off-kilter.

It began with an afternoon call from Rob Peterson, who was trying to get hold of Green and thought he might be with me. During the course of the conversation I discovered Green hadn't shown up at any of his classes for nearly a month, a figure that coincided uncomfortably well with the first of his six-to-midnight sessions in my basement. When I asked him about it later, Green admitted he'd been neglecting his schoolwork, but claimed he'd be able to catch up once he finished my shield. As usual, he stayed right at the edge of my range, so I wasn't able to confirm that he was telling the truth; and not wanting a scene I let him go back to work without further cross-examination. I soothed my conscience by reminding myself that he was a grown man, perfectly capable of deciding how to use his time.

But the whole thing seemed funny somehow-I couldn't reconcile this sudden neglect of his studies with the ambitious and calculating personality I'd already glimpsed in him. It bothered me; and gradually I began staying on the first floor whenever Green was in the house, where I could pick up his surface thoughts as he worked in the basement. He knew, of course-my footsteps would have been audible above him-and I could sense an almost frantic note in his attempts to cram his thoughts with technical details of his work. But enough got through. More than enough...

I waited until I was sure, and then I confronted him with it.

"You've had it for two weeks now, haven't you?" I said, anger struggling for supremacy with other emotions I was afraid to accept. "You know how to make a telepath shield."

"I don't know if I do," he protested. Hunched over the workbench, a soldering iron still gripped in his hand, he watched me with slightly narrowed eyes, as a rabbit might a fox. "I've never tested it."

Hairsplitting; but it was a genuine lack of certainty, and that had been enough to fool me for nearly a week. Belatedly, I wondered if perhaps I'd gotten the rabbit and fox roles reversed. "Well, let's not waste any more time. Turn it on."

"All right." Standing up, he went to the far end of the bench. A bulky, three-level breadboard assembly rested there, built into a framework that looked like it'd been made out of leftover angle iron. Three of Amos's kernels glittered among the tangle of electronic components. Plugging the device's cord into an outlet, Green flipped a switch and vanished.

It took a fraction of a second for my eyes to register the fact that Green was, in fact, still standing there in front of me, that it was only his mind that had disappeared from my perception. I must have looked as flabbergasted as I felt, because Green's lip twitched in a smile of sorts. "Like it?" he asked.

"I-yes," I managed. "How does it work?"

"I told you that was the approach to take," I said, feeling a little light-headed. "Will it block other telepaths, too? We project a lot more strongly than you do."

He shrugged. "Try calling someone."

I did; and because I was afraid of false hopes I tried for a solid three minutes. But at the end of that time I was convinced. Colleen... With an effort I dragged my mind back to Earth. One more important question still needed an answer. "All right. Now tell me what you've been doing these past two weeks, while you were supposedly working on the shield."

He radiated innocence. "I have been working on it-I've been trying to make a more practical model." He indicated the breadboards. "You see, this one is big and heavy, with an effective range of probably no more than a hundred feet, and it requires one-twenty line current. I think I can make one that would run off a battery and have almost half a mile of range-and the whole thing fitting inside a briefcase.

Another-oh, month or so-and I should have it."

It was a good idea, intellectually, I had to admit that. But all of my hopes and dreams had suddenly become reality and I knew I didn't have the patience to wait another day, let alone an entire month.

"Thanks, but no. This one will do fine."

He blinked, and I got the impression that my answer had surprised him. "But... I'm not finished here, Mr.

Ravenhall. I mean, I promised to build you a practical telepath shield. This thing's hardly practical."

"It's practical enough for me," I said, frowning. Goosebumps were beginning to form on my suspicions-he had no business fighting that hard for a two-dollar-an-hour job. "Before we continue, what say we make things more interesting and turn off the shield?"

He made no effort to reach for the switch. "That's not necessary," he sighed. "I was bending the truth a little. I've already been trying to design an entirely different gadget using those kernels, and I was afraid you'd send me away permanently once I'd finished the shield."

"What sort of gadget?"

"A mechanical mind reader."

"A what?"

"Well, why not? The kernels clearly pick up telepathic signals. Why shouldn't the signals be interpretable, by a small computer, say?"

I opened my mouth, closed it again as the potential repercussions of such a gadget echoed like heavy thunder through my mind. By necessity, each of us who'd had this gift/burden dropped on us had long ago thought out the consequences of misusing our power. The potential for blackmail, espionage of all kinds, or just simple invasion of privacy-I was personally convinced it was only our extremely limited number and the fact that we were thus easy to keep track of that had kept us from being locked up or killed outright. A mechanical device, presumably infinitely reproducible, would open up that entire can of worms, permanently. "Forget it," I said, finding my voice at last. "Thanks for the shield; I'll give you your final pay before you leave." I turned to go back upstairs.