"And you don't know _why_ your instruments measure whatever they're measuring." The Chicago man's face was thoughtful. "In fact, you can't really be certain that your instruments are measuring the children at all. It's not inconceivable that the _children_ might be measuring the _instruments_, eh?" Lessing blinked. "It's conceivable." "Mmmm," said Melrose. "Sounds like a real firm foundation to build a theory on." "Why not?" Lessing growled. "It wouldn't be the first time the tail wagged the dog. The psychiatrists never would have gotten out of their rut if somebody hadn't gotten smart and realized that one of their new drugs worked better in combatting schizophrenia when the doctor took the medicine instead of the patient. That was quite a wall to climb." "Yes, wasn't it," mused Melrose, scratching his bony jaw. "Only took them seventy years to climb it, thanks to a certain man's theories. I wonder how long it'll take psionics to crawl out of the pit you're digging for it?" "We're not digging any pit," Lessing exploded angrily. "We're exploring--nothing more. A phenomenon exists. We've known that, one way or another, for centuries. The fact that it doesn't seem to be bound by the same sort of natural law we've observed elsewhere doesn't mean that it isn't governed by natural law. But how can we define the law? How can we define the limits of the phenomenon, for that matter? We can't work in the dark forever--we've _got_ to have a working hypothesis to guide us." "So you dreamed up this 'tadpole' idea," said Melrose sourly. "For a working hypothesis--yes. We've known for a long time that every human being has extrasensory potential to one degree or another. Not just a few here and there--every single one. It's a differentiating quality of the human mind. Just as the ability to think logically in a crisis instead of giving way to panic is a differentiating quality." "Fine," said Melrose. "Great. We can't _prove_ that, of course, but I'll play along." Lessing glared at him. "When we began studying this psi-potential, we found out some curious things. For one thing, it seemed to be immensely more powerful and active in infants and children than in adults. Somewhere along the line as a child grows up, something happens. We don't know what. We do know that the child's psi-potential gradually withdraws deeper and deeper into his mind, burying itself farther and farther out of reach, just the way a tadpole's tail is absorbed deeper and deeper into the growing frog until there just isn't any tail any more." Lessing paused, packing tobacco into his pipe. "That's why we have the Farm--to try to discover why. What forces that potential underground? What buries it so deeply that adult human beings can't get at it any more?" "And you think you have an answer," said Melrose. "We think we might be near an answer. We have a theory that explains the available data."