Cloud frowned in concentration, but made no reply. Joan went on: “Assume, as a working hypothesis, that the vortices are concerned, in that exact relationship, with the increase in some kind of life. Since the fewer assumptions we make, the better, we don’t care at the moment what kind of life it is or whether it’s intelligent or not. To fit the curve, just what would the vortices have to be? Not houses, certainly . . . nor bedrooms . . . nor eggs, since they don’t hatch and the very oldest ones are still there, or would have been, except for you. . . . I’m about out of ideas. How about you?” “Maybe. My best guess would be incubators . . . and one-shot incubators at that. But with this new angle of approach I’ve got to re-evaluate the data and see what it means now.” He went over to the work-table, studied charts and diagrams briefly, then thumbed rapidly through a book of tables. He whistled raucously through his teeth. “This gets screwier by the minute, but it still checks. Every vortex represents _twins_. Never singles or triplets, _always_ twins. And the cycle is so long that the full span of our data isn’t enough to even validate a wild guess at it. Now, Joan, you baby expert, just what kind of an infant would be just comfortably warm and cosy in the middle of a loose atomic vortex? Feed _that_ one to Margie, chum, and let’s see what she does with it.” “I don’t have to; I can work it in my own little head. An exceedingly complex, exceedingly long-lived, exceedingly slow-growing baby of pure force. What else?” “Ugh! And Ugh! again. That’s twice you’ve slugged me right in the solar plexus.” Cloud began again to pace the floor. “Up to now, I was just having fun. . . . I’m mighty glad we don’t have to let anybody else in on this, the psychs would be on our tails in nothing flat . . . and the conclusion would be completely justifiable and we’ve both blown our stacks. . . . I’ve been trying to find holes in your theory . . . still am . . . but I can’t even _kick_ a hole in it. . . . “When one theory, and only one, fits much observational data and does not conflict with any, nor with any known or proven law or fact,” he said finally, aloud, “that theory, however bizarre, _must_ be explored. The only thing is, just how are we going to explore it?” “That’s what we have to work out.” “Just like that, eh? But before we start, tell me the rest of it—that stuff you’ve been keeping behind a solid block down there in the south-east corner of your mind.”