The basic of all morality is duty, a concept with the same relation to group that self-interest has to individual.

Our behavior is different. How often have you seen a headline like this?--TWO DIE ATTEMPTING RESCUE OF DROWNING CHILD. If a man gets lost in the mountains, hundreds will search and often two or three searchers are killed. But the next time somebody gets lost just as many volunteers turn out. Poor arithmetic, but very human. It runs through all our folklore, all human religions, all our literature--a racial conviction that when one human needs rescue, others should not count the price.

If you do not believe that a man will commit murder for one can of tomatoes, then you have never been hungry.

No matter where or what, there are makers, takers, and fakers.

Seems to be a deep instinct in human beings for making everything compulsory that isn't forbidden.

The lessons of history teach us - if the lessons of history teach us anything - that nobody learns the lessons that history teaches us.

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.