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.

My doctor said to me afterwards, 'When you were ill you behaved like a true philosopher. Every time you came to yourself you made a joke.' I never had a compliment that pleased me more.

Pure mathematics consists entirely of assertions to the effect that, if such and such a proposition is true of anything, then suchand such another proposition is true of that thing.... Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true.

We may define "faith" as the firm belief in something for which there is no evidence. Where there is evidence, no one speaks of "faith." We do not speak of faith that two and two are four or that the earth is round. We only speak of faith when we wish to substitute emotion for evidence. The substitution of emotion for evidence is apt to lead to strife, since different groups, substitute different emotions.

Nothing is so exhausting as indecision, and nothing is so futile.

You must believe that you can help bring about a better world. A good society is produced only by good individuals, just as truly as a majority in a presidential election is produced by the votes of single electors.

But as the work proceeded I was continually reminded of the fable about the elephant and the tortoise. Having constructed an elephant upon which the mathematical world could rest, I found the elephant tottering, and proceeded to construct a tortoise to keep the elephant from falling. But the tortoise was not more secure than the elephant, and after some twenty years of very arduous toil, I came to the conclusion that there was nothing more that I could do in the way of making mathematical knowledge indubitable.