One of the most painful circumstances of recent advances in science is that each one makes us know less than we thought we did

Extreme hopes are born of extreme misery, and in such a world hopes could only be irrational.

Only in thought is man a God; in action and desire we are the slaves of circumstance.

Science seems to be at war with itself.... Naive realism leads to physics, and physics, if true, shows naive realism to be false. Therefore naive realism, if true, is false; therefore it is false.

Although this may seem a paradox, all exact science is based on the idea of approximation. If a man tells you he knows a thing exactly, then you can be safe in inferring that you are speaking to an inexact man.

Africans had to be taught that nudity is wicked; this was done very cheaply by missionaries.

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