othesis on just such a situation.
Here, a race reaches high development and wrecks itself--leaving no
trace of its accomplishments. Growth starts over from the most meager of
beginnings. Survival becomes a matter of the most bitter conflict, with
everyone becoming a hunter and being hunted in his turn. In this
situation, detection of an enemy becomes vital." He grinned wryly. "Can
you imagine what would happen to someone who radiated his thoughts?"

Jaeger ran a finger over his lips. "He'd be easy to locate," he mused.
"And he'd have a hard time evading an enemy."

"Precisely." Kweiros nodded. "And he'd never be able to approach his
prey. In short, he'd fail to survive. Complete telepathic blankness
would have a high survival value. But an ability to detect mental
radiation would still be a big help." He waved a hand.

"So, a race like this one could evolve. And the author of this tape
extrapolated from there. A normal telepathic reception will be
accompanied, by a slight feedback. A completely black body, however,
will neither radiate nor feed back. It merely absorbs energy and, unless
it's super-imposed on a reflective background, it leaves no trace. Since
nothing in nature other than a telepathic mind can reflect telepathy, no
background would survive for long." He frowned a little.

"Of course, no mind we are familiar with could act as a telepathically
black body, but this author hypothesized a race that could do just
that--plus. There's a further hypothesis of an ability to detect and
localize radiations as such, without bothering to resolve them."

"Sounds like just what we have here," Jaeger admitted.

"It does, doesn't it?" Kweiros nodded. "And there's a further
extrapolation. Some of the members or the elder races have speculated on
a sort of second-order telepathy, undetectable to the normal telepath,
but capable of noting normal radiation. And some of the speculations
seem to make sense--though they're a little confusing. If you don't have
a specific sense, it's difficult to visualize it, or even to speculate
on its presence." He drew a deep breath.

"That leads us into a real problem. Our people roamed around this planet
for several cycles this time. And there may have been others before us,
who didn't record their visits, other than in the minds and legends of
the natives. And there may be other legends from that other, older
culture." He shrugged.

"We picked up what we could on the culture, but we