It would have to be a place where the working or not working of Aladdin’s lamp made absolutely no difference. Now, according to the legend, those two places, on two worlds, would actually be one place which was on both worlds, and which would serve as a perfectly practical gateway between them. Travelers would pass casually through it without ever noticing it. You and I perhaps, pass through such gateways every day without the least realization.”

The dark man seemed to find amused satisfaction in the look of mystified enthusiasm on Tony’s face. He waved a manicured hand.

“Look at this restaurant. Here. Tonight,” he said, beaming. “Today, for example, Calcutta could have vanished in a tidal wave and be sunk forever under the sea. Or it could not. Here and now, we knowing nothing about it, such an event would still have made no slightest difference. So that from this restaurant tonight we could walk out into two different worlds—you into the one where such an event had taken place, and I into the world where it did not. And I might go and live peacefully and die of old age in the Calcutta which to you was utterly destroyed.”

“But we are in the same world!” protested Tony. “We’ll stay in the same world!”

“Probably, but are you sure?” Mr. Emurian twinkled through his glasses. “We have never seen each other before. How do you know that I have always lived in this particular world? How do you know that the history of the world in which I was born is the same? I was surely not taught the same history! And if we separate here tonight, and you never see or hear of me again, how will you know that I remain in the world you inhabit?”

Tony said painfully, but with his heart beating fast:

“I—guess I won’t. But there’s no proof, either, that—”

“We agree,” said Mr. Emurian, nodding. “There can be no proof.