Behind their dark glass, the mad own nothing.

To every separate person a thing is what he thinks it is – in other words, not a thing, but a think.

Duty is what no-one else will do at the moment.

On the whole, I think you should write biographies of those you admire and respect, and novels about human beings who you think are sadly mistaken.

A word of advice. If, as a young man, student, you are tormented by a desire for women, it is best to get out into the fresh air as much as possible.

Helping other people is a drug so dangerous that there is no cure short of total abstention.

It's very good for an idea to be commonplace. The important thing is that a new idea should develop out of what is already there so that it soon becomes an old acquaintance. Old acquaintances aren't by any means always welcome, but at least one can't be mistaken as to who or what they are.