One of the chief triumphs of modern mathematics consists in having discovered what mathematics really is.

The most valuable things in life are not measured in monetary terms. The really important things are not houses and lands, stocks and bonds, automobiles and real state, but friendships, trust, confidence, empathy, mercy, love and faith.

Man needs, for his happiness, not only the enjoyment of this or that, but hope and enterprise and change.

More cranks take up unfashionable errors than unfashionable truths.

Science tells us what we can know, but what we can know is little, and if we forget how much we cannot know we become insensitive to many things of great importance.

There are some simple maxims which I think might be commended to writers of expository prose. First: never use a long word if a short word will do. So, if you want to make a statement with a great many qualifications, put some of the qualifications in separate sentences. Third: do not let the beginning of your sentence lead the reader to an expectation which is contradicted by the end.

There are three ways of securing a society that shall be stable as regards population. The first is that of birth control, the second that of infanticide or really destructive wars, and the third that of general misery except for a powerful minority.