Truly great men must, I think, experience great sorrow on the earth.

I am a sick man...I am a spiteful man. An unattractive man. I think that my liver hurts.

I have been tortured with longing to believe ... and the yearning grows stronger the more cogent the intellectual difficulties stand in the way.

originality and a feeling of one's own dignity are achieved only through work and struggle.

The man who has a conscience suffers whilst acknowledging his sin. That is his punishment.

To think too much is a disease.

Inventors and geniuses have almost always been looked on as no better than fools at the beginning of their career, and very frequently at the end of it also.