ared, could be made much simpler if they could
be trained to do their work instead of built so they couldn't help it.

Passenger-cars other than jeeps showed promise. It had long been known
that most accidents occurred with new cars, and that ancient jalopies
were relatively safe even in the hands of juvenile delinquents. It was
credible that part of the difference was in the operating habits of the
cars.

It appeared that humanity was upon the threshold of a new era, in which
the value of personality would reappear among the things taken for
granted. Strictly speaking, of course, Mahon machines were not persons.
But they reflected the personalities of their owners. It might again
seem desirable to be a decent human being if only because machines
worked better for them.

But it would be tragic if Mahon machines were used to destroy humankind
with themselves! Sergeant Bellews would have raged at the thought of
training a Mahon unit to guide an atom bomb. It would have to be--in a
fashion--deceived. He even disliked the necessity he faced that
afternoon while a courier winged his way to the Pentagon with the
top-secret tapes Betsy and Al and Gus had made.

The Rehab Shop was equipped not only to recondition machines but to test
them. One item of equipment was a generator of substitute broadcast
waves. It could deliver a carrier-wave down to half a micro-micro-watt
of any form desired, and up to the power of a nearby transmitter. It was
very useful for calibrating communicators. But Sergeant Bellews modified
it to allow of variations in type as well as frequency and amplitude.

"I'm betting," he grunted, "that there's different sorts of the
wave-type those guys want us to broadcast. Like there's a spectrum of
visible light. If we were color-blind and yellow'd bust things, they'd
transmit in red that we could see, and they'd tell us to broadcast
something in yellow that'd wipe us out. And we wouldn't have sense
enough not to broadcast the yellow, because we wouldn't know the
difference between it and red until we did broadcast. Then it'd be too
late."

Howell watched with tight-clamped jaws. He had committed himself to the
authenticity of the broadcasts claiming to be from a future time. Now he
was shaken, but only enough to admit the need for tests. Graves sat
unnaturally still. Lecky looked at Sergeant Bellews with a peculiarly
tranquil expression on his face.

"Only," grunted the sergeant, "it ain't frequency we