Our aim must be to make our successive mistakes as quickly as possible. To speed up evolution.

The initial stage, the act of conceiving or inventing a theory, seems to me neither to call for logical analysis nor to be susceptible of it.

We all remember how many religious wars were fought for a religion of love and gentleness; how many bodies were burned alive with the genuinely kind intention of saving souls from the eternal fire of hell.

We have become makers of our fate when we have ceased to pose as its prophets.

Definitions.... are never really needed, and rarely of any use

I don't know whether God exists or not. ... Some forms of atheism are arrogant and ignorant and should be rejected, but agnosticism—to admit that we don't know and to search—is all right. ... When I look at what I call the gift of life, I feel a gratitude which is in tune with some religious ideas of God. However, the moment I even speak of it, I am embarrassed that I may do something wrong to God in talking about God.

We should realize that, if [Socrates] demanded that the wisest men should rule, he clearly stressed that he did not mean the learned men; in fact, he was skeptical of all professional learnedness, whether it was that of the philosophers or of the learned men of his own generation, the Sophists. The wisdom he meant was of a different kind. It was simply the realization: how little do I know! Those who did not know this, he taught, knew nothing at all. This is the true scientific spirit.