It is only theory that makes men completely incautious.

Without effort and change, human life cannot remain good. It is not a finished Utopia that we ought to desire, but a world where imagination and hope are alive and active.

No satisfaction based upon self-deception is solid, and however unpleasant the truth may be, it is better to face it once and for all, to get used to it, and to proceed to build your life in accordance with it.

All religions are both harmful and untrue.

Religion is based ... mainly upon fear ... fear of the mysterious, fear of defeat, fear of death. Fear is the parent of cruelty, and therefore it is no wonder if cruelty and religion have gone hand in hand. My own view on religion is that of Lucretius. I regard it as a disease born of fear and as a source of untold misery to the human race.

At the age of eleven, I began Euclid, with my brother as my tutor. ... I had not imagined that there was anything so delicious in the world. After I had learned the fifth proposition, my brother told me that it was generally considered difficult, but I had found no difficulty whatsoever. This was the first time it had dawned on me that I might have some intelligence.

Philosophy is an unusually ingenious attempt to think fallaciously.