Bart's mouth twisted in a wry smile. "No," he said. "I could—I'm half Mentorian, I can even speak Lhari."

"Why don't you? I would."

"Oh, no, you wouldn't," Bart said softly. "Not even very many Mentorians will. You see, the Lhari don't trust humans too much. In the early days, men were always planting spies on Lhari ships, to try and steal the secret of warp-drive. They never managed it, but nowadays the Lhari give all the Mentorians what amounts to a brainwashing—deep hypnosis, before and after every voyage, so that they can neither look for anything that might threaten the Lhari monopoly of space, nor reveal it—even under a truth drug—if they find it out.

"You have to be pretty fanatical about space travel to go through that. Oh, my mother could tell us a lot of things about her cruises with the Lhari. The Lhari can't tell a diamond from a ruby, except by spectrographic analysis, for instance. And she—"

A high gong note sounded somewhere, touching off an explosion of warning bells and buzzers all over the enormous building. Bart looked up.

"The ship must be coming in to land."

"I'd better check into the passenger side," Tommy said. He stuck out his hand. "Well, Bart, I guess this is where we say good-bye."