I made some sort of reply. The couple eating with Rube across the room were the girl I'd seen practicing the Charleston and a young guy about the same age. Danziger saw me looking at them, and said, "Two more of the lucky ones: Ursula Dahnke and Franklin Miller. She was a high-school mathematics teacher in Eagle River, Wisconsin; he managed a Safeway store in Bakersfield, California. She's for the North Dakota farm, he's for Vimy Ridge; you probably saw him bayonet practicing this morning. I'll introduce you next time, but right now: How much do you know about Albert Einstein?"

"Well, he wore a button sweater, had bushy hair, and was terrible at arithmetic."

"Very good. There are only a few other things to say after that. Did you know that years ago Einstein theorized that light has weight? Now, that's about as silly a notion as a man could have formed. Not another human being in the world thought that or ever had; it contradicts every feeling we have about light." Danziger sat watching me for a moment; I was interested, and tried to look it. "But there was a way to test that theory. During eclipses of the sun, astronomers began observing that light passing it bent in toward it. Pulled by the sun's gravity, you see. Inescapably, that meant that light has weight: Albert Einstein was right, and he was off and running."

Danziger stopped for several spoonfuls of soup. My sandwich, I'd found, was pretty good: plenty of butter, and the cheese actually had some taste; I was hungry now. Danziger put down his spoon, touched his mouth with his napkin, and said, "Time passed. That astonishing mind continued to work. And Einstein announced that E equals MC squared. And, God forgive us, two Japanese cities disappeared in the blink of an eye and proved he was right again.

"I could go on; the list of Einstein's discoveries is a considerable one. But I'll skip to this: Presently he said that our ideas about time are largely mistaken. And I don't doubt for an instant that he was right once more. Because one of his final contributions not too long before he died was to prove that all his theories are unified. They're not separate but interconnected, each depending upon and confirming the others; they largely explain how the universe works, and it doesn't work as we'd thought."

He began peeling the red cellophane strip from the little package of crackers that came with his soup, looking at me, waiting. I said, "I've read a little on what he said about time, but I can't say I really know what he meant."

"He meant that we're mistaken in our conception of what the past, present and future really are. We think the past is gone, the future hasn't yet happened, and that only the present exists. Because the present is all we can see."

"Well, if you pinned me down, I'd have to admit that that's how it seems to me."

He smiled. "Of course. To me, too. It's only natural. As Einstein himself pointed out. He said we're like people in a boat without oars drifting along a winding river. Around us we see only the present. We can't see the past, back in the bends and curves behind us. But it's there."

"Did he mean that literally, though? Or did he mean —»

"He always meant exactly what he said. When he said light has weight, he meant that the sunlight lying on a field of wheat actually weighs several tons. And now we know — it's been measured — that it really does. He meant that the tremendous energy theoretically binding atoms together could really be released in one unimaginable burst. As it really can, a fact that has changed the course of the human race. He also meant precisely what he said about time: that the past, back there around the curves and bends, really exists. It is actually there." For maybe a dozen seconds Danziger was silent, his fingers playing with the little red cellophane strip. Then he looked up and said simply, "I am a theoretical physicist on leave here from Harvard University. And my own tiny extension of Einstein's giant theory is… that a man ought somehow to be able to step out of that boat onto the shore. And walk back to one of the bends behind us."

I was struggling to keep a thought from showing in my eyes: that this might be an intelligently, plausibly, mildly deluded old man who'd persuaded a lot of people in New York and Washington to join him in constructing a warehouse full of fantasies. Could it possibly be that I was the only one who'd guessed? Maybe not; this morning Rossoff had made a joke — an uneasy one? — about my joining a booby hatch. I nodded thoughtfully. "Walk back how?"

Danziger had a little soup left, and now he finished it, tipping his bowl to get the last of it, and I finished my sandwich. Then he raised his head, his eyes looked directly into mine, and I looked back into his and knew that Danziger wasn't crazy. He was eccentric, very possibly mistaken, but he was sane, and I was suddenly glad I was here. He said, "What day is this?"

"Thursday."

"What date?"

"The… twenty-sixth, isn't it?"

"You tell me."

"The twenty-sixth."

"What month?"

"November."

"And year?"

I told him; I was smiling a little now.

"How do you know?"

Waiting for a reply to form itself in my mind, I sat staring across the table at Danziger's intent, bald-headed face; then I shrugged. "I don't know what you want me to say."

"Then I'll answer for you. You know the year, the day and the month, for literally millions of reasons: because the blanket you woke up under this morning may have been at least partly synthetic; because there is probably a box in your apartment with a switch; turn that switch, and the faces of living human beings will appear on a glass screen in the face of that box and speak nonsense to you. Because red and green lights signaled when you might cross a street on your way here this morning; and because the soles of the shoes you walked in are a synthetic that will outlast leather.

"Because the fire engine that passed you sounded a hooter, not a siren; because the teen-aged children you saw were dressed as they were; and because the Negro you walked by eyed you warily, as you did him, each of you trying to conceal it. Because the front page of the Times looked precisely as it did this morning and as it never will again or ever has before. And because millions and millions and millions of still other such facts will confront you all day long.

"Most of them are possible only in this century, many only in the latter half of it. Some are possible only this decade, some only this year, others only this month, and a few only on this particular day. Si, you are surrounded by literally countless facts that bind you to this century… year… month… day… and moment, like ten billion invisible threads."

He picked up his fork to cut into his pie, but instead he raised it to touch his forehead with the handle. "And in here there are millions more of those invisible threads. Your knowledge, for example, of who is President at this moment of history. That Frank Sinatra could now be a grandfather. That buffalo no longer roam the prairie, and that Kaiser Wilhelm isn't generally considered too much of a threat any more. That our coins are now made of copper, not silver. That Ernest Hemingway is dead, everything is turning to plastic, and that things don't go one bit better with Coke. The list is endless, all of it a part of your own consciousness and of the common consciousness. And it binds you as it binds us all to the day and to the very moment when precisely that list and only that list is possible. You never escape it, and I'll show you why." Danziger crushed his paper napkin and set it on the edge of his plate. "Finished? Want anything more?"

"No, that was fine. Thank you."

"Pretty frugal lunch but good for you. So they say. Let's go up on the roof. I'll take my pie along."