Outsiders began to decay,
and the humans were forced to demand their removal. The machines were
unaffected by them, but the rapid change told them why it was that so
thorough an execution was necessary. The foreign bacteria were already
at work on totally unresisting tissue.

It was Roal who sent the first thoughts among the gathered men.

"It is evident," he began, "that the machines must defend man. Man is
defenseless, he is destroyed by these beams, while the machines are
unharmed, uninterrupted. Life--cruel life--has shown its tendencies.
They have come here to take over these planets, and have started out
with the first, natural moves of any invading life-form. They are
destroying the life, the intelligent life particularly, that is here
now." He gave vent to that little chuckle which is the human sign of
amusement and pleasure. "They are destroying the intelligent life--and
leaving untouched that which is necessarily their deadliest enemy--the
machines.

"You--machines--are far more intelligent than we even now, and capable
of changing overnight, capable of infinite adaptation to circumstance;
you live as readily on Pluto as on Mercury or Earth. Any place is a
home-world to you. You can adapt yourselves to any condition. And--most
dangerous to them--you can do it instantly. You are their most deadly
enemies, and they realize it. They have no intelligent machines;
probably they can conceive of none. When you attack them, they merely
say 'The life-form of Earth is sending out controlled machines. We will
find good machines we can use.' They do not conceive that those machines
which they hope to use are attacking them.

"Attack--therefore!"

"We can readily solve the hidden secret of their force-screen."

* * * *

He was interrupted. One of the newest science-machines was speaking.
"The secret of the force-screen is simple." A small ray-machine, which
had landed near, rose into the air at the command of the
scientist-machine, X-5638 it was, and trained upon it the deadly
induction beam. Already, with his parts, X-5638 had constructed the
defensive apparatus, for the ray fell harmless from his screen.

"Very good," said Roal softly. "It is done, and therein lies their
danger. Already it is done.

"Man is a poor thing, unable to change himself in a period of less than
thousands of years. Already you have changed yourself. I noticed your
weaving tentacles, and your force-beams. You t