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.

Customs tell a man who he is, where he belongs, what he must do. Better illogical customs than none; men cannot live together without them.

Love is that condition in which the happiness of another person is essential to your own.

Obscurity is the refuge of incompetence.

I never do anything I don't want to do. Nor does anyone, but in my case I am always aware of it.

The Earth is just too small and fragile a basket for the human race to keep all its eggs in.

Democracy is based on the assumption that a million men are wiser than one man. How's that again? I missed something.