unless it understands itself. The symbiosis between all life-forms on our planet is the result of that knowledge. We should like to assure ourselves that you are capable of understanding your own kind as well before we offer our services to your Terran Realm—and therein lies the test we have arranged for you."

Captain Corelli drew himself up stiffly. "I think," he said, "that the three of us should be able to unravel your little riddle, if you'll condescend to tell us what it is."

Gaffa sent a puzzled look at the Quack, and I could see that he was wondering why Corelli hadn't included him in the boast. But Gaffa didn't know how simple the Quack could be, nor how preoccupied with his own physiology he was.

"One of these two," said Gaffa, pointing to the two Haslops, "is the original Ira Haslop, who was stranded here twenty-two Terran years ago. The other is a synthetic creation of ours—an android, if you like, who is identical, cell by cell, with the original so far as exterior likeness is concerned. We could not duplicate the interior without dissection, which of course was out of the question, so we were forced to make compromises that—"

Gibbons interrupted him incredulously. "You mean you've created a living creature, brain and all?"

"Only the body," Gaffa said. "Creation of intelligence is still beyond us. The brain of the duplicate Haslop is one of our own, transplanted and conditioned to Haslop's knowledge, memories and ideology."

He paused for a moment, and the waiting circle of Balakians grinned with him in anticipation.

"Your problem is this," Gaffa said. "If you know yourselves well enough to merit our help, then you should be able to distinguish readily between the real and false Haslops. If you fail, we shall have no alternative but to keep you here on Balak for the rest of your lives, since to release you would bring other Terrans down on us in force."

And that was it. All we had to do was to take these two identical twins—who looked alike, thought alike and cursed alike—and determine which was real and which was bogus.

"For a very pertinent reason which you may or may not discover," Gaffa said, "the test must be limited to a few hours. You have until sunrise tomorrow morning, gentlemen."

And with that he crutched away at his skip-a-step walk, taking his grinning cohorts with him. The two Haslops remained behind, glowering and grumbling at each other.

The situation didn't look too bad at first.

"There are no two things," Captain Corelli declared, "that are exactly and absolutely identical. And that applies, I should say, especially to identities."

It had a heartening sound. I've never been long on logic, being a very ordinary S.E. navigator whose automatic equipment is designed to do practically everything for him, and Corelli seemed to know what he was talking about.

Gibbons, being a scientist, saw it differently.

"That's not even good sophistry," he said. "The concept of identity between two objects has no meaning whatever, Captain, unless we have a prior identification of one or the other. Aristotle himself couldn't have told an apple from a coconut if he'd never seen or heard of either."

"Any fool would know that," one of the Haslops grunted. And the other added in the same tone: "Hey, if you guys are going at it like that, we'll be here forever!"

"All right," Corelli said, deflated. "We'll try another tack."

He thought for a minute or two. "How about screening them for background detail? The real Haslop was a bounty-claimer, which means that he must have made thousands of planetfalls before crashing here. The bogus one couldn't remember the details of all those worlds as well as the original, no matter how many times he'd been told, could he?"

"Won't work," one of the Haslops said disgustedly. "Hell, after twenty-two years I can't remember those places myself, and I was there."

The other Haslop gave him a dirty look. "You were