In a practical tone: “That is how I perceived that you were about to sabotage us, Captain. Your posture alone betrayed you. I guessed the means at once and ordered the guards to knock you unconscious. I think, also, that I detected in you the potential I need. But that demands closer examination. Which is easily given. When I am linked, you cannot lie to me. The least insincerity is written across your whole organism.”

He paused, to stand a little slumped, looking at the bulkhead. For a moment Diaz’s legs tensed. Three jumps and I can be there and get his gun! But no, Rostock wasn’t any brainheavy dwarf. The body in that green uniform was young and trained. Diaz took another cigarette. “Okay,” he said. “What do you propose?”

“First,” Rostock said, turning about—and his eyes kindled—“I want you to understand what you and I are. What the spacemen of both factions are.”

“Professional soldiers,” Diaz grunted uneasily. Rostock waited. Diaz puffed hard and plowed on, since he was plainly expected to, “The last soldiers left. You can’t count those ornamental regiments on Earth, nor the guys sitting by the big missiles. Those missiles will never be fired. World War Three was a large enough dose of nucleonics. Civilization was lucky to survive. Terrestrial life would be lucky to survive, next time around. So war has moved into space. Uh…professionalism…the old traditions of mutual respect and so forth have naturally revived.” He made himself look up. “What more clichés need I repeat?”

“Suppose your side completely annihilated our ships,” Rostock said. “What would happen?”

“Why…that’s been discussed theoretically…by damn near every political scientist, hasn’t it? The total command of space would not mean total command of Earth. We could destroy the whole Eastern Hemisphere without being touched. But we wouldn’t, because Unasia would fire its cobalt weapons while dying, and we’d have no Western Hemisphere to come home to, either. Not that that situation will ever arise. Space is too big; there are too many ships and fortresses scattered around; combat is too slow a process. Neither fleet can wipe out the other.”

“Since we have this perpetual stalemate, then,” Rostock pursued, “why do we have perpetual war?”

“Um…well, not really. Cease-fires—”

“Breathing spells! Come now, Captain, you are too intelligent to believe that rigmarole. If victory cannot be achieved, why fight?”

“Well, uh, partial victories are possible. Like our capture of Mars, or your destruction of three dreadnaughts in one month, on different occasions. The balance of power shifts. Rather than let its strength continue being whittled down, the side which is losing asks for a parley. Negotiations follow, which end to the relative advantage of the stronger side. Meanwhile the arms race continues. Pretty soon a new dispute arises, the cease-fire ends, and maybe the other side is lucky that time.”

“Is this situation expected to be eternal?”

“No!” Diaz stopped, thought a minute, and grinned with one corner of his mouth. “That is, they keep talking about an effective international organization. Trouble is, the two cultures are too far apart by now. They can’t live together.”