This has been my life. I have found it worth living, and would gladly live it again if the second chance were offered me.

Although this may seem a paradox, all exact science is dominated by the idea of approximation. When a man tells you that he knows the exact truth about anything, you are safe in inferring that he is an inexact man. Every careful measurement in science is always given with the probable error ... every observer admits that he is likely wrong, and knows about how much wrong he is likely to be.

Freedom in general may be defined as the absence of obstacles to the realization of desires.

One of the chief obstacles to intelligence is credulity, and credulity could be enormously diminished by instructions as to the prevalent forms of mendacity. Credulity is a greater evil in the present day than it ever was before, because, owing to the growth of education, it is much easier than it used to be to spread misinformation, and, owing to democracy, the spread of misinformation is more important than in former times to the holders of power.

I do not think any reasonable person can doubt that in India, China and Japan, if the knowledge of birth control existed, the birthrate would fall very rapidly

One of the symptoms of approaching nervous breakdown is the belief that one's work is terribly important, and that to take a holiday would bring all kinds of disaster. If I were a medical man, I should prescribe a holiday to any patient who considered his or her work important.

The harm that theology has done is not to create cruel impulses, but to give them the sanction of what professes to be lofty ethic, and to confer an apparently sacred character upon practices which have come down from more ignorant and barbarous times.