H. Beam Piper

“ Think of the changes if this thing we were discussing, Columbus sailing under the English flag, had happened. Or suppose Leif Ericson had been able to plant a permanent colony in America in the Eleventh Century, or if the Saracens had won the Battle of Tours. Try to imagine the world today if any of those things had happened. One thing you can be sure of—any errors you make in trying to imagine such a world will be on the side of over-conservatism. ”

“ I simply won't destroy it, but I can think of nobody to whom I'd be willing to show it—certainly nobody at the college, my History Department colleagues least of all. Merely to tell the story would brand me irredeemably as a crackpot, but crackpots are tolerated, even on college faculties. It's only when they begin producing physical evidence that they get themselves actively resented.
When I went into the club-car for a nightcap before going back to my compartment to turn in, there were five men there, sitting together. ”

“ You shouldn't emphasize the event that could have changed history; you should emphasize the changes that could have been made. You're going to end this show you were talking about with a shot of Columbus wading up to the beach with an English flag, aren't you? ”

“ Don't try to get them both in one; a collaboration would really be better. Then you work from the known situation in Europe and in America in 1492, and decide on the immediate effects. And from that, you have to carry it along, step by step, down to the present. It would be a lot of hard and very exacting work, but the result would be worth it." He took a sip from his glass and added: "Remember, you don't have to prove that the world today would be the way you set it up. All you have to do is make sure that nobody else would be able to prove that it wouldn't." ”

“ Reports like that usually get the ignore-and-forget treatment, now."
"Zen you believe zat zeese ozzer world of zee alternate probabeelitay, zey exist?"
"No. I don't disbelieve it, either. I've no reason to, one way or another." He studied his drink for a moment, and lowered the level in the glass slightly. "I've said that once in a while things get reported that look as though such other worlds, in another time-dimension, may exist. There have been whole books published by people who collect stories like that. I must say that academic science isn't very hospitable to them." ”

“ There's absolutely no evidence to support it, and scientists don't accept unsupported assumptions unless they need them to explain something, and they don't need this assumption for anything. Well, it would come in handy to make some of these reports of freak phenomena, like mysterious appearances and disappearances, or flying-object sightings, or reported falls of non-meteoric matter, theoretically respectable. ”

“ But they don't speak accented English, and they don't dress eccentrically. You know there's an enemy agent in a crowd, pick out the most normally American type in sight and you usually won't have to look further."
The train ground to a stop. A young couple with hand-luggage came in and sat at one end of the car, waiting until other accommodations could be found for them. After a while, it started again. I dallied over my drink, and then got up and excused myself, saying that I wanted to turn in early. ”