We have found that where science has progressed the farthest, the mind has but regained from nature that which the mind put into nature.

Asked in 1919 whether it was true that only three people in the world understood the theory of general relativity, [Eddington] allegedly replied: "Who's the third?"

It is also a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.

In Einstein's theory of relativity the observer is a man who sets out in quest of truth armed with a measuring-rod. In quantum theory he sets out with a sieve.

It is impossible to trap modern physics into predicting anything with perfect determinism because it deals with probabilities from the outset.

Electrical force is defined as something which causes motion of electrical charge; an electrical charge is something which exerts electric force.

Every body continues in its state of rest or uniform motion in a straight line, except insofar as it doesn't.