I have spoken to Einstein and he admitted to me that his theory was in fact no different from the one of Parmenides.

There will be well-testable theories, hardly testable theories, and non-testable theories. Those which are non-testable are of no interest to empirical scientists. They may be described as metaphysical.

There is no history of mankind, there is only an indefinite number of histories of all kinds of aspects of human life.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.

If we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.

Man, some modern philosophers tell us, is alienated from his world: he is a stranger and afraid in a world he never made. Perhaps he is; yet so are animals, and even plants. They too were born, long ago, into a physico-chemical world, a world they never made.

The history of science is everywhere speculative. It is a marvelous hiatory. It makes you proud to be a human being.