Quote of the Day: sine qua non

"But it is true that whenever we develop machinery to the point where it will support large populations at a high standard of living we are then bound to keep that machinery running, or suffer the consequences. But the real hazard in that is not the machinery, but the men who run the machinery...When a population is dependent on a machine, they are hostages of the men who tend the machines."

From The Roads Must Roll by Robert Heinlein.