I can't tell whether I am living in a dream or a nightmare.

In the great depression, things could only be set right by causing the idle plant to work again . . . Roosevelt . . . spent billions of public money and created a huge public debt, but by so doing he revived production and brought his country out of the depression. Businessmen, who in spite of such a sharp lesson continued to believe in old-fashioned economics, were infinitely shocked, and although Roosevelt saved them from ruin, they continued to curse him and to speak of him as 'the madman in the White House.' . . . [It's one more] striking example of inability to learn from experience.

Conquer the world by intelligence, and not merely by being slavishly subdued by the terror that comes from it.

The significance of a fact is relative to [the general body of scientific] knowledge. To say that a fact is significant in science, is to say that it helps to establish or refute some general law; for science, though it starts from observation of the particular, is not concerned essentially with the particular, but with the general. A fact, in science, is not a mere fact, but an instance. In this the scientist differs from the artist, who, if he deigns to notice facts at all, is likely to notice them in all their particularity.

It is only in marriage with the world that our ideals can bear fruit; divorced from it, they remain barren.

Man is a credulous animal, and must believe something; in the absence of good grounds for belief, he will be satisfied with bad ones.

Science, in its ultimate ideal, consists of a set of propositions arranged in a hierarchy, the lowest level of the hierarchy being concerned with particular facts, and the highest with some general law, governing everything in the universe. The various levels in the hierarchy have a two-fold logical connection, travelling one up, one down; the upward connection proceeds by induction, the downward by deduction.