The creation of wealth is certainly not to be despised, but in the long run the only human activities really worthwhile are the search for knowledge, and the creation of beauty. This is beyond argument, the only point of debate is which comes first.

I am an optimist. Anyone interested in the future has to be otherwise he would simply shoot himself.

There were some things that only time could cure. Evil men could be destroyed, but nothing could be done with good men who were deluded.

We stand now at the turning point between two eras. Behind us is a past to which we can never return...

As three laws were good enough for Newton, I have modestly decided to stop there.

A faith that cannot survive collision with the truth is not worth many regrets.

The dinosaurs disappeared because they could not adapt to their changing environment. We shall disappear if we cannot adapt to an environment that now contains spaceships, computers - and thermonuclear weapons.