Three great forces rule the world: stupidity, fear and greed.

Politics is for the present, but an equation is for eternity.

There are few enough people with sufficient independence to see the weaknesses and follies of their contemporaries and remain themselves untouched by them.

Pure logical thinking cannot yield us any knowledge of the empirical world. All knowledge of reality starts from experience and ends in it.

Problems cannot be solved by thinking within the framework in which the problems were created.

The only reason for time is so that everything doesn't happen at once.

The single most important decision any of us will ever make is whether or not to believe the universe is friendly.