There have been poverty, pestilence, and famine, which were due to man's inadequate mastery of nature. There have been wars, oppressions and tortures which have been due to men's hostility to their fellow men.

The wise man thinks about his troubles only when there is some purpose in doing so; at other times he thinks about other things, or, if it is night, about nothing at all.

There may be no good reasons for very many opinions that are held with passion.

The key to happiness is accepting one unpleasant reality every day.

Those whose lives are fruitful to themselves, to their friends, or to the world are inspired by hope and sustained by joy: they see in imagination the things that might be and the way in which they are to be brought into existence.

One must expect a war between U.S.A. and U.S.S.R. which will begin with the total destruction of London. I think the war will last 30 years, and leave a world without civilised people, from which everything will have to build afresh - a process taking (say) 500 years.

What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth.