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.

There is a great difference between believing in something and believing in it again.

The construction of the universe is certainly very much easier to explain than is that of the plant.

I forget most of what I read, just as I do most of what I have eaten, but I know that both contribute no less to the conservation of my mind and my body on that account.

To make astute people believe one is what one is not is, in most cases, harder than actually to become what one wishes to appear.

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

A good method of discovery is to imagine certain members of a system removed and then see how what is left would behave: for example, where would we be if iron were absent from the world: this is an old example.