"All right," agreed Dan. "Grant that. The Porcyns plainly don't have any of those things, or not to any great extent. Instead, they have institutions such as we've never seen before. They have 'sweepers,' so-called 'vacations' and a rope from building to building. All these things cut down population." "Don't forget their 'truth chairs,'" said Kielgaard. "Where you either tell the truth or get converted to ashes--yes. But how does it all fit in?" "Let's take one individual as an example. Start at birth." "He's born," said Dan. "Probably they have nurseries, but we know they stick together as families, because we have the Milbuns to go by. He grows up, living at his parents' place. He goes with other children to school or to see different parts of his city. A lion--which he calls a 'dog'--protects him." "Yes," said Kielgaard. "It protects him from sweepers. But most grownups don't need protection. Only those whose charge is low." "Of course. The boy hasn't been on vacation yet. He's not radioactive. Apparently you have to be radioactive to open doors. At the apartment house, the boy comes in a small door to one side. The lions, or what resemble lions, like the children but don't like the sweepers. And the sweepers are afraid of them. All right. But what about when he grows up?" "Well, for one thing, he has to use the regular doors now. And they won't open unless he's been on vacation. And if he hasn't been on vacation and if his charge isn't high, the sweepers will go out and grab him. That must be what that sign you saw meant. 'Swept' was a warning that there was no escape in that direction." "I begin to see it," said Dan. "I was safe on that road because the birth rate in that section wasn't high. But in the city, the birth rate _was_ high, so, to keep the population down, the standards were raised. Apparently the sweepers were fed less and got more hungry. People had to go on vacation more often. But what about the rope?" * * * * * "I don't think we really know enough to understand the rope," said Kielgaard, "but maybe it's a face-saving device. People who don't think they're in good enough shape to get through 'vacation,' and who don't want to die a slow death avoiding sweepers and waiting to go through locked doors, can go across on the rope. Or perhaps it's a penance. If a man has done something wrong and he's afraid to deny it in the truth chair, perhaps he's allowed to confess and go so many times across the rope as punishment. The people cheered. That must mean it's honorable." "That makes sense," Dan agreed. "All right, but why don't they just ship their surplus population to the other two planets?"