"They didn't tell me where they came from, except that it was outside the solar system, nor just how they got to Ganymede. Not by themselves, though, because they couldn't even exist by themselves. They must have got as far as Ganymede as parasites of visitors that had landed there at some time or other. Maybe millions of years ago. And they couldn't get off Ganymede, of course, till we landed there. Space travel hadn't developed on Ganymede--" * * * * * Charlie interrupted me again, "But if they were so smart, why didn't they develop it themselves?" "They couldn't," I told him. "They weren't any smarter than the minds they occupied. Well, a little smarter, in a way, because they could use those minds to their full capacity and people--Terrestrial or Ganymedean--don't do that. But even the full capacity of the mind of a Ganymedean savage wasn't sufficient to develop a space-ship. "But now they had _us_--I mean, they had Lecky and Haynes and Hilda and Art and Dick--and they had our space-ship, and they were going to Earth, because they knew all about it and about conditions there from our minds. They planned, simply, to take over Earth and--uh--_run_ it. They didn't explain the details of how they propagate, but I gathered that there wouldn't be any shortage of earrings to go around, on Earth. Earrings or bracelets or, however, they'd attach themselves. "Bracelets, probably, or arm or leg bands, because wearing earrings like that would be too conspicuous on Earth, and they'd have to work in secret for a while. Take over a few people at a time, without letting the others know what was going on. "And Lecky--or the thing that was running Lecky--told me they'd been using me as a guinea pig, that they could have put a ring on me, taken me over, at any time. But they wanted a check on how they were doing at imitating normal people. They wanted to know whether or not I got suspicious and guessed the truth. "So Dick--or the thing that was running him--had kept himself out of sight under Dick's sleeve, so if I got suspicious of the others, I'd talk it over with Dick--just as I really did do. And that let them know they needed a lot more practice animating those bodies before they took the ship back to Earth to start their campaign there. "And, well, that was the whole story and they told it to me to watch my reactions, as a normal human. And then Lecky took a ring out of his pocket and held it out toward me with one hand, keeping the pistol on me with the other hand. "He told me I might as well put it on because if I didn't, he could shoot me first and then put it on me--but that they greatly preferred to take over undamaged bodies and that it would be better for me, too, if I--that is, my body--didn't die first. "But naturally, I didn't see it that way. I pretended to reach out for the ring, hesitantly, but instead I batted the gun out of his hand, and made a dive for it as it hit the floor.