sufficient. I can equal it, since both generation and
projection are implicit in the formula. But the data so adduced are in
themselves vastly ahead of anything previously in my banks."

"Are there any other races in this Galaxy more powerful than the
postulated one now living on Fuel World?"

"Data insufficient."

"Theorize, then!"

"Data insufficient."

The linked minds concentrated upon the problem for a period of time that
might have been either days or weeks. Then:

"Great Brain, advise us," Ynos said. "What is best for us to do?"

"With identical defensive screens it becomes a question of relative
power. You should increase the size and power of your warships to
something beyond the computed probable maximum of the enemy. You should
build more ships and missiles than they will probably be able to build.
Then and only then will you attack their warships, in tremendous force
and continuously."

"But not their planetary defenses. I see." Ynos's thought was one of
complete understanding. "And the _real_ offensive will be?"

"No mobile structure can be built to mount mechanisms of power
sufficient to smash down by sheer force of output such tremendously
powerful installations as their planet-based defenses must be assumed
to be. Therefore the planet itself must be destroyed. This will require
a missile of planetary mass. The best such missile is the tenth planet
of their own sun."

* * * * *

"I see." Ynos's mind was leaping ahead, considering hundreds of
possibilities and making highly intricate and involved computations.
"That will, however, require many cycles of time and more power than
even our immense reserves can supply."

"True. It will take much time. The fuel problem, however, is not a
serious one, since Fuel World is not unique. Think on, First Lord Ynos."

"We will attack in maximum force and with maximum violence. We will
blanket the planet. We will maintain maximum force and violence until
most or all of the enemy ships have been destroyed. We will then install
planetary drives on Ten and force it into collision orbit with Fuel
World, meanwhile exerting extreme precautions that not so much as a
spy-beam emerges above the enemy's screen. Then, still maintaining
extreme precaution, we will guard both planets until the last possible
moment before the collision. Brain, it cannot fail!"

"You err. It can fail. All we actually know of the abilities of this
postul