So long as there are men, there will be wars.

I never made one of my discoveries through the process of rational thinking

[Freud's] sense of reality is less clouded by wishful thinking than is the case with other people and [he combines] the qualities of critical judgment, earnestness and responsibility.

If you cannot explain it simply, you do not understand it enough.

If I could do it all again, I'd be a plumber.

Creating a new theory is not like destroying an old barn and erecting a skyscraper in its place. It is rather like climbing a mountain, gaining new and wider views, discovering unexpected connections between our starting points and its rich environment. But the point from which we started out still exists and can be seen, although it appears smaller and forms a tiny part of our broad view gained by the mastery of the obstacles on our adventurous way up.

Nothing causes more consternation in a group of hypocrits than one honest man.