When the facts change, I change my mind. What do you do, sir?

A study of the history of opinion is a necessary preliminary to the emancipation of the mind

The social object of skilled investment should be to defeat the dark forces of time and ignorance which envelope our future.

It would not be foolish to contemplate the possibility of a far greater progress still.

The difficulty lies not so much in developing new ideas as in escaping from old ones.

There is no harm in being sometimes wrong - especially if one is promptly found out.