Because the results are expressed in numbers, it is easy to make the mistake of thinking that the intelligence test is a measure like a foot ruler or a pair of scales. It is, of course, a quite different sort of measure. Intelligence is not an abstraction like length and weight; it is an exceedingly complicated notion - which nobody has yet succeeded in defining.

The ordinary politician has a very low estimate of human nature. In his daily life he comes into contact chiefly with persons who want to get something or to avoid something. Beyond this circle of seekers after privileges, individuals and organized minorities, he is aware of a large unorganized, indifferent mass of citizens who ask nothing in particular and rarely complain. The politician comes after a while to think that the art of politics is to satisfy the seekers after favors and to mollify the inchoate mass with noble sentiments and patriotic phrases.

There is but one bond of peace that is both permanent and enriching: The increasing knowledge of the world in which experiment occurs.

The smashing of idols is in itself such a preoccupation that it is almost impossible for the iconoclast to look clearly into a future when there will not be many idols left to smash.

A free press is not a privilege but an organic necessity in a great society. ... A great society is simply a big and complicated urban society.

A man cannot be a good doctor and keep telephoning his broker between patients nor a good lawyer with his eye on the ticker.

When everyone thinks the same, nobody is thinking.