From Unless it Moves the Human Heart: The Craft and Art of Writing, by Roger Rosenblatt:
"Everything contains significance. But some significances are more equal than others. The writers whom we agree are the great ones only deal in matters of proved importance. They are great because their subjects and themes are great, and thus their usefulness is great as well. Their souls are great, and they have had the good sense and courage to consult their souls before their pens touched paper."