A conceptual scheme is never discarded merely because of a few stubborn facts with which it cannot be reconciled a conceptual scheme is either modified or replaced by a better one, never abandoned with nothing left to take its place.

It seems as though I were in a lunatic asylum, but I am never sure who is the attendant and who the inmate.

... scientific research is compounded of ... empirical procedures, general speculative ideas, and mathematical or abstract reasoning.

Some of mankind's most terrible misdeeds have been committed under the spell of certain magic words or phrases.

Every vital organization owes its birth and life to an exciting and daring idea.

Each honest calling, each walk of life, has its own elite, its own aristocracy based on excellence.

Whether a man lives or dies in vain can be measured only by the way he faces his own problems, by the success or failure of the inner conflict within his own soul. And of this no one may know save God.

Education is what is left after all that has been learnt is forgotten.

The dignity of man is vindicated as much by the thinker and poet as by the statesman and soldier.

Behold the turtle. He makes progress only when he sticks his neck out.

The stumbling way in which even the ablest of the scientists in every generation have had to fight through thickets of erroneous observations, misleading generalizations, inadequate formulation, and unconscious prejudice is rarely appreciated by those who obtain their scientific knowledge from textbooks.

Just like a turtle, we only make progress if we stick our neck out.

Science emerges from the other progressive activities of man to the extent that new concepts arise from experiments and observations, and that the new concepts in turn lead to further experiments and observations.