nothing puts me so completely out of patience as the utterance of a wretched commonplace when I am talking from my inmost heart.

A great artist... must be shaken by the naked truths that will not be comforted. This divine discontent, this disequilibrium, this state of inner tension is the source of artistic energy.

Night is the other half of life, and the better half.

Hatred is a heavy burden. It sinks the heart deep in the breast, and lies like a tombstone on all joys.

The credit of advancing science has always been due to individuals and never to the age.

A mathematician is only perfect insofar as he is a perfect man, sensitive to the beauty of truth.

Doubt can only be removed by action.