If any philosopher had been asked for a definition of infinity, he might have produced some unintelligible rigmarole, but he would certainly not have been able to give a definition that had any meaning at all.

Suppose atomic bombs had reduced the population of the world to one brother and sister; should they let the human race die out?

Some people would rather die than think.

More and more people are becoming unable to accept traditional [religious] beliefs. If they think that, apart from these beliefs, there is no reason for kindly behaviour, the results may be needlessly unfortunate. That is why it is important to show that no supernatural reasons are needed to make [people] kind and to prove that only through kindness can the human race achieve happiness.

None but a coward dares to boast that he has never known fear.

To be out of harmony with one's surroundings is of course a misfortune, but it is not always a misfortune to be avoided at all costs. Where the environment is stupid or prejudiced or cruel, it is a sign of merit to be out of harmony with it.

It's not what you have lost, but what you have left that counts.