Mathematics takes us into the region of absolute necessity, to which not only the actual word, but every possible word, must conform.

I say quite deliberately that the Christian religion, as organized in its Churches, has been and still is the principal enemy of moral progress in the world.

One of the symptoms of an approaching nervous breakdown is the belief that one's work is terribly important.

We have in fact, two kinds of morality, side by side: one which we preach, but do not practice, and another which we practice, but seldom preach.

I am delighted to know that Principia Mathematica can now be done by machinery. . . I am quite willing to believe that anything in deductive logic can be done by machinery.

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

The habit of looking to the future and thinking that the whole meaning of the present lies in what it will bring forth is a pernicious one. There can be no value in the whole unless there is value in the parts.