The problem was that this early success did not translate itself into any sort of financial security. The science-fiction magazines of that early day paid a cent a word at best, and Campbell’s primary market, Amazing Stories, paid on publication, which meant he could wait as long as two years before seeing any return on his work. And, major figure that he was to science-fiction readers, he was not doing well in the mundane world. He had flunked out of M.I.T. in his junior year after three times failing to pass his German course, a required subject. After that embarrassing debacle he enrolled at Duke University, where, after an intensive summer course in German, he finally was able to come away with a degree in 1934. By then he had married, and, unable to earn a real-world living from his writing, he had embarked on a series of undistinguished jobs—car salesman, air-conditioner salesman, and a secretarial job at Mack Trucks, among others—but never managed to keep any of them very long.
His writing career was presenting difficulties, too. F. Orlin Tremaine, the astute editor of Astounding, had begun to think that readers were tiring of the sort of super-science tales that had brought Campbell his early fame, wordy epics in which grim, methodical supermen repeatedly saved the world from menacing aliens by mastering, with the greatest of ease, such things as faster—than-light travel, the fabrication of matter-destroying rays, the release of atomic energy, and the penetration of hyperspace. In 1935 Campbell turned in three lengthy sequels to The Mightiest Machine and Tremaine rejected all three. He had no place else to sell them, since Amazing Stories already was holding a novel of his for which it had not yet paid, and Wonder Stories, the third of the three science-fiction magazines of the day, was in financial trouble and buying very little new material, and the failure of the three novellas left him in harsh financial circumstances.
Having exhausted the possibilities of the high-tech galactic epic on which he had built his fame, Campbell somewhat desperately began to reposition himself as a writer. At Tremaine’s suggestion he began a series of moody, poetic stories of the far future under the pseudonym of “Don A. Stuart”. These, beginning with the haunting, visionary “Twilight” and going on to “Blindness,” “The Machine,” “Night,” and several others, were an immediate success with the readers of Astounding. Seeking to escape from the low—pay world of the science-fiction pulps, Campbell looked toward Argosy, a weekly magazine of general fiction noted for publishing fantastic novels by such writers as Edgar Rice Burroughs and A. Merritt and paying quite well for them. He tried them with Frozen Hell, a tight, tense novel about a lunar expedition stranded on the Moon, which had not interested Tremaine. But it was written in diary form, a mode not ideally suited to the demands of the magazine readers of the day for fast-paced fiction, and neither Argosy nor any other magazine cared for it. (It finally saw print in 1951, published by a small press under the title of The Moon is Hell.)With the heavy-science epic no longer marketable, and the moody Don A. Stuart stories insufficient to support him by themselves, Campbell needed to find something different to write, and, with the help of a new editor named Mort Weisinger, he undertook a series of potboilers in the comic mode of Stanley G. Weinbaum, an immensely popular writer who had died in 1935 after a brief, spectacular career. Weinbaum was a natural storyteller with a distinctive light touch, and his work had won him a wide following, beginning in 1934 in Hugo Gernsback’s Wonder Stories with “A Martian Odyssey,” still often reprinted in anthologies, and continuing until his death eighteen months later. The sales of Wonder Stories were approaching the vanishing point early in 1936, and Gernsback sold it to the aptly named Standard Magazines, a chain of pulps that dealt in simply told action-adventure stories for young readers, which renamed it Thrilling Wonder Stories. Weisinger, a long-time science-fiction fan who was put in charge, was aware that Weinbaum had been the old magazine’s readers’ favorite, and, with Weinbaum no longer available, he called in John Campbell and asked him to write a series of stories in the Weinbaum manner.
Campbell, hard pressed to pay his rent at the time, eagerly complied. The usual Weinbaum plot had involved space explorers who become entangled in some complicated manner with alien beings, and though Campbell’s published work had been anything but lighthearted up until then, he proposed a group of breezy Weinbaumian tales featuring two space travelers named Penton and Blake. The first one Campbell turned in, in the spring of 1936, was “Imitation,” to which Weisinger gave the livelier title of “Brain-Stealers of Mars” when he ran it in the December 1936 issue of Thrilling Wonder Stories.
“Brain-Stealers” begins in a cheerfully Weinbaumian way. Penton and Blake, having caused some trouble on Earth by touching off an atomic explosion in the course of an experiment, jump into a spaceship and take off for Mars. They are puzzled to find what look like Japanese maple trees there, and also weirder-looking plants, weird plants and animals having been a Weinbaum specialty. Before long things get stranger: the Japanese maples change form, becoming something very alien; and then Penton and Blake find themselves surrounded by some twenty duplicate Pentons and Blakes, identical in all respects, including voices, personalities, and memories.
They respond fairly casually at first, Blake shooting one of the extra Pentons with his atomic pistol when it begins to show signs of further physical change, then eliminating some of the others. Then centaur-like creatures show up—Martian natives, quite friendly, who explain telepathically that the shapeshifters are creatures called thushol that have the power of transforming themselves into perfect imitations of other life-forms.
“How do you tell them from the thing they’re imitating?” Penton asks.
“It used to bother us because we couldn’t,” one of the centaurs replies. “But it doesn’t any more.”
“I know—but how do you tell them apart? Do you do it by mind-reading?”
“Oh, no. We don’t try to tell them apart. That way they don’t bother us any more.”
The centaurs are untroubled by the presence of shapeshifters in their midst (“If the imitation is so perfect we can’t tell the difference, what’s the difference?”), but Penton and Blake see real danger in it, and abruptly what had been an amiable Weinbaumian romp takes on a much darker tone. What if some future explorer from Earth inadvertently brings a thushol back from Mars? “If they eat like an amoeba,” Penton says, “God help us. If you maroon one on a desert island, it will turn into a fish, and swim home. If you put it in jail it will turn into a snake and go down the drain pipe. If you dump it in the desert it will turn into a cactus and get along real nice, thank you.” The thushol, he saw, were infinitely adaptive creatures that could conquer and absorb all enemies, and if they somehow managed to get to Earth it would mean the end of the human race.
The thing to do, they realize, is to return to Earth immediately. But all about them are duplicate Pentons and Blakes, indistinguishable from the originals. How can each of the authentic Earthmen be certain that no thushol has taken the place of the other one for the return voyage? Some reliable way of determining authenticity is needed; and after a time Penton devises one, an ingenious biological test, quite Weinbaumian in nature, that allows them to identify and destroy all the false Pentons and Blakes in their midst. The world is saved and the story ends with a wry Weinbaumian punchline.