John Steinbeck said this quote

The writer is delegated to declare and to celebrate man's proven capacity for greatness of heart and spirit—for gallantry in defeat, for courage, compassion and love. In the endless war against weakness and despair, these are the bright rally flags of hope and of emulation. I hold that a writer who does not believe in the perfectibility of man has no dedication nor any membership in literature.—Steinbeck Nobel Prize Acceptance Speech