The Three Theorems of Psychohistorical Quantitivity: The population under scrutiny is oblivious to the existence of the science of Psychohistory. The time periods dealt with are in the region of 3 generations. The population must be in the billions (±75 billions) for a statistical probability to have a psychohistorical validity.
Isaac AsimovNaturally, since [the Sumerians] didn't know what caused the flood anymore than we do, they blamed the gods. (That's the advantage of religion. You're never short an explanation for anything.)
Isaac AsimovWhen asked for advice by beginners. Know your ending, I say, or the river of your story may finally sink into the desert sands and never reach the sea.
Isaac AsimovEven as a youngster, though, I could not bring myself to believe that if knowledge presented danger, the solution was ignorance.
Isaac Asimov