The writing of "Nightfall" was a watershed in my professional career. When I wrote it, I had just turned twenty-one. I had been writing professionally (in the sense that I was submitting my stories to magazines and occasionally selling them) for two and a half years, but had created no tidal wave. I had published about a dozen stories and had failed to sell a dozen others.

 Then John W. Campbell, Jr., the editor of Astounding Science Fiction, showed me the Emerson quotation that starts "Nightfall." We discussed it; then I went home and, over the course of the next few weeks, wrote the story.

 Now let's get something straight. I didn't write that story any differently from the way I had written my earlier stories-or, for that matter, from the way I wrote my later stories. As far as writing is concerned, I am a complete and utter primitive. I have no formal training at all and to this very day I don't know How To Write.

 I just write any old way it comes into my mind to write and just as fast as it comes into my mind.

 And that's the way I wrote "Nightfall."

 Mr. Campbell never sends letters of acceptance. He sends checks, instead, and very promptly, and that is an excellent way of handling the matter. I always found it thrilling. I received a check for "Nightfall" but my initial pang of delight was almost instantly snuffed out by the fact that Mr. Campbell had made a mistake.

 Standard payment at that time was a munificent 1 cent a word. (No complaints, folks; I was glad to get it.) The story was 12,000 words long and therefore I expected $120.00, but the check was for $15.00.

 I groaned. It would be so simple to cash the check and ask no questions, but the Ten Commandments, as preached to me by my stern and rockbound father, made it absolutely necessary to call Mr. Campbell at once and make arrangements for a new and smaller check.

 It turned out there was no mistake. The story seemed so good to Mr. Campbell that he gave me a bonus of ј cent a word.

 I had never, till then, received so huge a payment for any story, and that was just the beginning. When the story appeared, it was given the lead position and the cover.

 What's more, I was suddenly taken seriously and the world of science fiction became aware that I existed. As the years passed, in fact, it became evident that I had written a "classic." It has appeared in ten anthologies that I know of-including one British, one Dutch, one German, one Italian, and one Russian.

 I must say, though, that as time passed, I began to feel some irritation at being told, over and over again, that "Nightfall" was my best story. It seemed to me, after all, that although I know no more about Writing now than I knew then, sheer practice should have made me more proficient, technically, with each year.

 The thing has preyed on my mind, in fact, until the idea of this book came to me.

 First appearance-Astounding Science Fiction, September 1941. Copyright, 1941, by Street amp; Smith Publications, Inc.; copyright renewed, 1968, by Isaac Asimov.

 I have never included "Nightfall" in any of my own collections of stories because it always seemed to me to have been so well anthologized that it must be familiar to all my readers. Yet perhaps that's not so. Most of my readers weren't even born when the story first appeared and perhaps many of them haven't seen the anthologies.

 Besides, if it's my best story, then I want it in one of my own collections. I can also include other stories of mine that have proven successful in one way or another but have not appeared in any of my own collections.

 So, with Doubleday's kind permission, I have prepared Nightfall and Other Stories, with all the tales in the order of publication. "Nightfall" itself is the first and now you can see for yourself how my writing has developed (or has failed to develop) with the years. Then you can decide for yourself why (or if) "Nightfall" is better than the others.

 I don't know enough about Writing to be able to tell.

Aton 77, director of Saro University, thrust out a belligerent lower lip and glared at the young newspaperman in a hot fury.

Theremon 762 took that fury in his stride. In his earlier days, when his now widely syndicated column was only a mad idea in a cub reporter's mind, he had specialized in 'impossible' interviews. It had cost him bruises, black eyes, and broken bones; but it had given him an ample supply of coolness and self-confidence.

So he lowered the outthrust hand that had been so pointedly ignored and calmly waited for the aged director to get over the worst. Astronomers were queer ducks, anyway, and if Aton's actions of the last two months meant anything; this same Aton was the queer-duckiest of the lot.

Aton 77 found his voice, and though it trembled with restrained emotion, the careful, somewhat pedantic phraseology, for which the famous astronomer was noted, did not abandon him.

"Sir," he said, "you display an infernal gall in coming to me with that impudent proposition of yours."

The husky telephotographer of the Observatory, Beenay 25, thrust a tongue's tip across dry lips and interposed nervously, "Now, sir, after all - "

The director turned to him and lifted a white eyebrow. "Do not interfere, Beenay. I will credit you with good intentions in bringing this man here; but I will tolerate no insubordination now."

Theremon decided it was time to take a part. "Director Aton, if you'll let me finish what I started saying, I think - "

"I don't believe, young man," retorted Aton, "that anything you could say now would count much as compared with your daily columns of these last two months. You have led a vast newspaper campaign against the efforts of myself and my colleagues to organize the world against the menace which it is now too late to avert. You have done your best with your highly personal attacks to make the staff of this Observatory objects of ridicule."

The director lifted a copy of the Saro City Chronicle from the table and shook it at Theremon furiously. "Even a person of your well-known impudence should have hesitated before coming to me with a request that he be allowed to cover today's events for his paper. Of all newsmen, you!"

Aton dashed the newspaper to the floor, strode to the window, and clasped his arms behind his back.

"You may leave," he snapped over his shoulder. He stared moodily out at the skyline where Gamma, the brightest of the planet's six suns, was setting. It had already faded and yellowed into the horizon mists, and Aton knew he would never see it again as a sane man.

He whirled. "No, wait, come here!" He gestured peremptorily. I'll give you your story."

The newsman had made no motion to leave, and now he approached the old man slowly. Aton gestured outward. "Of the six suns, only Beta is left in the sky. Do you see it?"

The question was rather unnecessary. Beta was almost at zenith, its ruddy light flooding the landscape to an unusual orange as the brilliant rays of setting Gamma died. Beta was at aphelion. It was small; smaller than Theremon had ever seen it before, and for the moment it was undisputed ruler of Lagash's sky.