A theory that explains everything, explains nothing

The method of science depends on our attempts to describe the world with simple theories: theories that are complex may become untestable, even if they happen to be true. Science may be described as the art of systematic over-simplification-the art of discerning what we may with advantage omit.

If we wish our civilization to survive we must break with the habit of deference to great men.

No number of sightings of white swans can prove the theory that all swans are white. The sighting of just one black one may disprove it.

The survival value of intelligence is that it allows us to extinct a bad idea, before the idea extincts us.

A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.

No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it