Let it be understood, in the first place, that a science fiction story must be an exposition of a scientific theme and it must be also a story.
“Business is never so healthy as when, like a chicken, it must do a certain amount of scratching around for what it gets.”
“Since the day of the air, the old frontiers are gone. When you think of the defense of England you no longer think of the chalk cliffs of Dover; you think of the Rhine.”