What is called an acute knowledge of human nature is mostly nothing but the observer's own weaknesses reflected back from others.

The Greeks possessed a knowledge of human nature we seem hardly able to attain to without passing through the strengthening hibernation of a new barbarism.

One must judge men not by their opinions, but by what their opinions have made of them.

Prejudices are so to speak the mechanical instincts of men: through their prejudices they do without any effort many things they would find too difficult to think through to the point of resolving to do them.

We cannot remember too often that when we observe nature, and especially the ordering of nature, it is always ourselves alone we are observing.