An hour-glass is a reminder not only of time's quick flight, but also of the dust to which we must at last return

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 has to do something new in order to see something new.

A book which, above all others in the world, should be forbidden, is a catalogue of forbidden books.

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

Nothing can contribute more to peace of soul than the lack of any opinion whatever.

Ambition and suspicion always go together.