It is sometimes important for science to know how to forget the things she is surest of.
There are things that don't deserve to be said briefly.
In our ideals we unwittingly reveal our vices.
When I was young I pitied the old. Now old, it is the young I pity.
To say of men that they are bad is to say they are worse than we think we are, or worse than the ideal man whose image we have built up on the basis of a certain few.
What makes our opponents useful is that they allow us to believe that without them we would be able to realize our goals.