The demand for certainty is one which is natural to man, but is nevertheless an intellectual vice. So long as men are not trained to withhold judgment in the absence of evidence, they will be led astray by cocksure prophets, and it is likely that their leaders will be either ignorant fanatics or dishonest charlatans. To endure uncertainty is difficult, but so are most of the other virtues.

[Kant] was like many people: in intellectual matters he was skeptical, but in moral matters he believed imjplicitly in the maximx that he had imbibed at his mother's knee.

I consider the official Catholic attitude on divorce, birth control, and censorship exceedingly dangerous to mankind.

Fear is the main source of superstition, and one of the main sources of cruelty. To conquer fear is the beginning of wisdom.

Formality Thus the absence of all mention of particular things or properties in logic or pure mathematics is a necessary result of the fact that this study is, as we say, "purely formal".

Beggars do not envy millionaires, though of course they will envy other beggars who are more successful.

Envy ... is one form of a vice, partly moral, partly intellectual, which consists in seeing things never in themselves but only in their relations.