Science advances, not by the accumulation of new facts, but by the continuous development of new concepts.

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

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.

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

In every section of the entire area where the word science may properly be applied, the limiting factor is a human one. We shall have rapid or slow advance in this direction or in that depending on the number of really first-class men who are engaged in the work in question. ... So in the last analysis, the future of science in this country will be determined by our basic educational policy.

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

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.