"Anyway," Robert was saying, "you haven't any imagination." He sank down cross-legged on the floor. "You can't teleport yourself to any place that's never been." She went over to squat down beside him. "I can, too! What about the Moon People? They haven't been yet." He looked at her with childish disgust. "Oh, Star, they have so been. You know that." He spread his hands out as though he were a baseball referee. "That time hasn't been yet for your daddy here, for instance, but it's already been for somebody like--well, say, like those things from Arcturus." "Well, neither have you teleported yourself to some place that never was," Star was arguing back. "So there." * * * * * Waving Jim to one chair, I sank down shakily into another. At least the arms of the chair felt solid beneath my hands. "Now, look, kids," I interrupted their evasive tactics. "Let's start at the beginning. I gather you've figured a way to travel to places in the past or future." "Well, of course. Daddy." Star shrugged the statement aside nonchalantly. "We just TP ourselves by ESP anywhere we want to go. It doesn't do any harm." And these were the children who were too little to cross the street! I have been through times of shock before. This was the same--somehow, the mind becomes too stunned to react beyond a point. One simply plows through the rest, the best he can, almost normally. "Okay, okay," I said, and was surprised to hear the same tone I would have used over an argument about the biggest piece of cake. "I don't know whether it's harmful or not. I'll have to think it over. Right now, just tell me how you do it." "It would be so much easier if I could ESP it to you," Star said doubtfully. "Well, pretend I'm a Stupid and tell me in words." "You remember the Moebius Strip?" she asked very slowly and carefully, starting with the first and most basic point in almost the way one explains to an ordinary child. Yes, I remembered it. And I remembered how long ago it was that she had discovered it. Over a year, and her busy, brilliant mind had been exploring its possibilities ever since. And I thought she had forgotten it! "That's where you join the ends of a strip of paper together with a half twist to make one surface," she went on, as though jogging my undependable, slow memory. "Yes," I answered. "We all know the Moebius Strip." Jim looked startled. I had never told him about the incident. "Next you take a sheet and you give it a half twist and join the edge to itself all over to make a funny kind of holder." "Klein's Bottle," Jim supplied. She looked at him in relief. "Oh, you know about that," she said. "That makes it easier. Well, then, the next step. You take a cube"--Her face clouded with doubt again, and she explained, "You can't do this with your hands. You've gotta ESP it done, because it's an imaginary cube anyway." She looked at us questioningly. I nodded for her to continue.