Everyone is perfectly willing to learn from unpleasant experience - if only the damage of the first lesson could be repaired.

Nothing puts a greater obstacle in the way of the progress of knowledge than thinking that one knows what one does not yet know.

He swallowed a lot of wisdom, but all of it seems to have gone down the wrong way.

The highest point to which a weak but experienced mind can rise is detecting the weakness of better men.

Perseverance can lend the appearance of dignity and grandeur to many actions, just as silence in company affords wisdom and apparent intelligence to a stupid person.

One's first step in wisdom is to question everything - and one's last is to come to terms with everything.

I have remarked very clearly that I am often of one opinion when I am lying down and of another when I am standing up.