have
admitted that a machine in the act of operating was a dynamic system in
a solid group of objects, but nobody reflected that a stopped machine
was a dead thing. Nobody thought to liken the warming-up period for an
aeroplane engine to the days of playing before a disuse-dulled violin
regained its tone.

Yet it was obvious enough. A ship and a sword and a tool and a violin
were objects in which dynamic systems existed when they were used, and
in which they ceased to exist when use stopped. And nobody noticed that
a living creature is an object which contains a dynamic system when it
is living, and loses it by death.

For nearly two centuries quite complex machines were started, and warmed
up, and used, and then allowed to grow cold again. In time the more
complex machines were stopped only reluctantly. Computers, for example,
came to be merely turned down below operating voltage when not in use,
because warming them up was so difficult and exacting a task. Which was
an unrecognized use of the Mahon principle. It was a way to keep a
machine activated while not actually operating. It was a state of rest,
of loafing, of idleness, which was not the death of a running mechanism.

The Mahon unit was a logical development. It was an absurdly simple
device, and not in the least like a brain. But to the surprise of
everybody, including its inventor, a Mahon-modified machine did more
than stay warmed up. It retained operative habits as no complex device
had ever done before. In time it was recognized that Mahon-modified
machines acquired experience and kept it so long as the standby light
glowed and flickered in its socket. If the lamp went out the machine
died, and when reenergized was a different individual entirely, without
experience.

Sergeant Bellews made such large-minded statements as were needed to
brief Lecky on the work done in this installation with Mahon-controlled
machines.

"They don't think," he explained negligently, "any more than dogs think.
They just react--like dogs do. They get patterns of reaction. They get
trained. Experienced. They get good! Over at the airfield they're
walking around beaming happy over the way the jets are flyin'
themselves."

Lecky gazed around the Rehab Shop. There were shelves of machines, duly
boxed and equipped with Mahon units, but not yet activated. Activation
meant turning them on and giving them a sort of basic training in the
tasks they were designed to do. But also t