"That's a thought," said Padway. "It's bad enough knowing the sun might become a nova, but if we're also likely to vanish because somebody has gone back to the twelfth century and stirred things up—"
"No. That has never happened. We have never vanished, that is. You see, doctor? We continue to exist, but another history has been started. Perhaps there are many such, all existing somewhere. Maybe, they aren't much different from ours. Maybe the man comes to rest in the middle of the ocean. So what? The fish eat him, and things go on as before. Or they think he is mad, and shut him up or kill him. Again, not much difference. But suppose he becomes a king or a duce? What then?
"Presto, we have a new history! History is a four-dimensional web. It is a tough web. But it has weak points. The junction places—the focal points, one might say—are weak. The back-slipping, if it happens, would happen at these places."
"What do you mean by focal points?" asked Padway. It sounded to him like polysyllabic nonsense.
"Oh, places like Rome, where the world-lines of many famous events intersect. Or Istanbul. Or Babylon. You remember that archaeologist, Skrzetuski, who disappeared at Babylon in 1936?"
"I thought he was killed by some Arab holdup men."
"Ah. They never found his body! Now, Rome may soon again be the intersection point of great events. That means the web is weakening again here."
"I hope they don't bomb the Forum," said Padway.
"Oh, nothing like that. Our Duce is much too clever to get us into a real war. But let us not talk politics. The web, as I say, is tough. If a man did slip back, it would take a terrible lot of work to distort it. Like a fly in a spider web that fills a room."
"Pleasant thought," said Padway.