Dialogue has to show not only something about the speaker that is its own revelation, but also maybe something about the speaker that he doesn't know but the other character does know.
Eudora WeltyMy mother read secondarily for information; she sank as a hedonist into novels. She read Dickens in the spirit in which she would have eloped with him.
Eudora WeltyFor the night was not impartial. No, the night loved some more than others, served some more than others.
Eudora Welty