Of All Possible Worlds By WILLIAM TENN Illustrated by GAUGHAN [Transcriber's Note: This etext was produced from Galaxy Science Fiction December 1956. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] Changing the world is simple; the trick is to do it before you have a chance to undo it! It was a good job and Max Alben knew whom he had to thank for it--his great-grandfather. "Good old Giovanni Albeni," he muttered as he hurried into the laboratory slightly ahead of the escorting technicians, all of them, despite the excitement of the moment, remembering to bob their heads deferentially at the half-dozen full-fleshed and hard-faced men lolling on the couches that had been set up around the time machine. He shrugged rapidly out of his rags, as he had been instructed in the anteroom, and stepped into the housing of the enormous mechanism. This was the first time he had seen it, since he had been taught how to operate it on a dummy model, and now he stared at the great transparent coils and the susurrating energy bubble with much respect. This machine, the pride and the hope of 2089, was something almost outside his powers of comprehension. But Max Alben knew how to run it, and he knew, roughly, what it was supposed to accomplish. He knew also that this was the first backward journey of any great duration and, being scientifically unpredictable, might well be the death of him. "Good old Giovanni Albeni," he muttered again affectionately. If his great-grandfather had not volunteered for the earliest time-travel experiments way back in the nineteen-seventies, back even before the Blight, it would never have been discovered that he and his seed possessed a great deal of immunity to extra-temporal blackout. And if that had not been discovered, the ruling powers of Earth, more than a century later, would never have plucked Max Alben out of an obscure civil-service job as a relief guard at the North American Chicken Reservation to his present heroic and remunerative eminence. He would still be patrolling the barbed wire that surrounded the three white leghorn hens and two roosters--about one-sixth of the known livestock wealth of the Western Hemisphere--thoroughly content with the half-pail of dried apricots he received each and every payday. No, if his great-grandfather had not demonstrated long ago his unique capacity for remaining conscious during time travel, Max Alben would not now be shifting from foot to foot in a physics laboratory, facing the black market kings of the world and awaiting their final instructions with an uncertain and submissive grin. * * * * *