Quarantine was first published in the premier issue of Isaac Asimov's Science Fiction Magazine. The following notes by Arthur C. Clarke were printed along with the story:
(Reprinted by permission of the author's agents, Scovil Chichak Galen Literary Agency, Inc.)

"To my considerable astonishment, I find that it is more than five years since I last wrote a short story (in case you're dying to know, it was A Meeting with Medusa). This was composed for one specific purpose - to complete the long overdue volume The Wind from the Sun; and having done this, I have had no incentive to produce any more short fiction. Or, for that matter, short non-fiction; only yesterday I gently informed the Editor of the U.S.S.R.'s Writers' Union's magazine, 'Questions of Literature' that, from now on, I am writing novels - or nothing at all. (And I have already achieved a whole year of blissful nothingness, hurrah.)

"Yet from time to time lightning may strike. This occurred exactly a year ago as a result of a suggestion from George Hay, editor and man-about-British-SF. George had the ingenious idea of putting out a complete science fiction short story on a postcard - together with a stamp-sized photo of the author. Fans would, he believed, buy these in hundreds to mail out to their friends.

"Never one to resist a challenge, the Good Doctor Asimov had written the first cardboard epic. When I saw this, I had to get into the act as well ('Anything that Isaac can do, etc.-..'). Let me tell you - it is damned hard work writing a complete SF story in 180 words. I sent the result to George Hay, and that's the last I ever heard of it. Probably the rising cost of postage killed the scheme.

"Anyway, it seems appropriate that a magazine bearing the Good Doctor's Sacred Name should contain a story, however minuscule, inspired by him. (He is likewise to blame for 'Neutron Tide'; I can make worse puns than Isaac.) It is also perfectly possible - I make no promises - that 'Quarantine' is the last short story I shall ever write. For at my present average of 40 words a year, even by 2001-"

Quarrantine

Earth's flaming debris still filled half the sky when the question filtered up to Central from the Curiosity Generator.

"Why was it necessary? Even though they were organic, they had reached Third Order Intelligence."

"We had no choice: five earlier units became hopelessly infected, when they made contact."

"Infected? How?"

The microseconds dragged slowly by, while Central tracked down the few fading memories that had leaked past the Censor Gate, when the heavily-buffered Reconnaissance Circuits had been ordered to self-destruct.

"They encountered a - problem - that could not be fully analyzed within the lifetime of the Universe. Though it involved only six operators, they became totally obsessed by it."

"How is that possible?"

"We do not know: we must never know. But if those six operators are ever re-discovered, all rational computing will end."

"How can they be recognized?"

"That also we do not know; only the names leaked through before the Censor Gate closed. Of course, they mean nothing."

"Nevertheless, I must have them."

The Censor voltage started to rise; but it did not trigger the Gate.

"Here they are: King, Queen, Bishop, Knight, Rook, Pawn."

Isaac Asimov's Science Fiction Magazine, First Issue, Vol 1, No. 1, Spring 1977