The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.

In considering irregular appearances, there are certain very natural mistakes which must be avoided.

The experience of overcoming fear is extraordinarily delightful.

The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.

Can a society in which thought and technique are scientific persist for a long period, as, for example, ancient Egypt persisted, or does it necessarily contain within itself forces which must bring either decay or explosion?

Human life, its growth, its hopes, fears, loves, et cetera, are the result of accidents

Thought is subversive and revolutionary, destructive and terrible, Thought is merciless to privilege, established institutions, and comfortable habit. Thought is great and swift and free.