Broderick clasped his hands behind back, went to the window and stared down moodily into the street.
"You don't know what an overcrowded world is like," he said. "A street like this, with so few people and vehicles on it, would be impossible on Earth."
"But it's mobbed," protested Zotul. "It gave me a headache."
"And to us it's almost empty. The pressure of population on Earth has made us range the Galaxy for places to put our extra people. The only habitable planets, unfortunately, are populated ones. We take the least populous worlds and—well, buy them out and move in."
"And after that?"
Broderick smiled gently. "Zur will grow. Our people will intermarry with yours. The future population of Zur will be neither true Zurians nor true Earthmen, but a mixture of both."
Zotul sat in silent thought. "But you did not have to buy us out. You had the power to conquer us, even to destroy us. The whole planet could have been yours alone." He stopped in alarm. "Or am I suggesting an idea that didn't occur to you?"
"No," said Broderick, his usually smiling face almost pained with memory. "We know the history of conquest all too well. Our method causes more distress than we like to inflict, but it's better—and more sure—than war and invasion by force. Now that the unpleasant job is finished, we can repair the dislocations."
"At last I understand what you said about the tortoise."