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.

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

Each honest calling, each walk of life, has its own elite, its own aristocracy based on excellence of performance. . . . There will always be the false snobbery which tries to place one vocation above another. You will become a member of the aristocracy in the American sense only if your accomplishments and integrity earn this appellation.

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

Behavior which appears superficially correct but is intrinsically corrupt always irritates those who see below the surface.

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.