An armed man need not fight.

Never underestimate the power of human stupidity.

The most expensive thing in the world is a second-best military establishment, good but not good enough to win.

The Universe was a silly place at best...but the least likely explanation for it was the no-explanation of random chance, the conceit that abstract somethings 'just happened' to be atoms that 'just happened' to get together in ways which 'just happened' to look like consistent laws and some configurations 'just happened' to possess self-awareness and that two 'just happened' to be the Man from Mars and a bald-headed old coot with Jubal inside.

The best thing about space travel is that it made it possible to go elsewhere.

But space travel can't ease the pressure on a planet grown too crowded not even with today's ships and probably not with any future ships-because stupid people won't leave the slopes of their home volcano even when it starts to smoke and rumble. What space travel does do is drain off the best brains: those smart enough to see a catastrophe before it happens, and with the guts to pay the price-abandon home, wealth, friends, relatives, everything-and go. That's a tiny fraction of one percent. But that's enough.

The most noble fate a man can endure is to place his own mortal body between his loved home and the war's desolation.