They drank beer and reminisced as men will who have met after long separation. They called to mind the days under fire. They remembered sergeants and girls, both with exaggeration. Deadly things became humorous in retrospect, and trifles disregarded for ten years were hauled out for airing.

Including, of course, the perennial mystery.

"How do you account for it?" asked the first. "Who started it?"

The second shrugged. "No one started it. Everyone was doing it, like a disease. You, too, I suppose."

The first chuckled.

The third one said softly, "I never saw the fun in it. Maybe because I came across it first when I was under fire for the first time. North Africa."

"Really?" said the second.

"The first night on the beaches of Oran. I was getting under cover, making for some native shack and I saw it in the light of a flare-"

George was deliriously happy. Two years of red tape and now he was finally back in the past. Now he could complete his paper on the social life of the foot soldier of World War II with some authentic details.

Out of the warless, insipid society of the thirtieth century, he found himself for one glorious moment in the tense, superlative drama of the warlike twentieth.

North Africa! Site of the first great sea-borne invasion of the war! How the temporal physicists had scanned the area for the perfect spot and moment. This shadow of an empty wooden building was it. No human would approach for a known number of minutes. No blast would seriously affect it in that time. By being there, George would not affect history. He would be that ideal of the temporal physicist, the "pure observer."

It was even more terrific than he had imagined. There was the perpetual roar of artillery, the unseen tearing of planes overhead. There were the periodic lines of tracer bullets splitting the sky and the occasional ghastly glow of a flare twisting downward.

And he was here! He, George, was part of the war, part of an intense kind of life forever gone from the world of the thirtieth century, grown tame and gentle.

He imagined he could see the shadows of an advancing column of soldiers, hear the low cautious monosyllables slip from one to another. How he longed to be one of them in truth, not merely a momentary intruder, a "pure observer."

He stopped his note taking and stared at his stylus, its micro-light hypnotizing him for a moment. A sudden idea had overwhelmed him and he looked at the wood against which his shoulder pressed. This moment must not pass unforgotten into history. Surely doing this would affect nothing. He would use the older English dialect and there would be no suspicion.

He did it quickly and then spied a soldier running desperately toward the structure, dodging a burst of bullets. George knew his time was up, and, even as he knew it, found himself back in the thirtieth century.

It didn't matter. For those few minutes he had been part of World War II. A small part, but part. And others would know it. They might not know they knew it, but someone perhaps would repeat the message to himself.

Someone, perhaps that man running for shelter, would read it and know that along with all the heroes of the twentieth century was the "pure observer," the man from the thirtieth century, George Kilroy. He was there!