Sad songs, it has been said, say so much. (They are also, as fans of Mr. Show already know, nature’s onions , but I digress.) The lyrics of Lorenz Hart typically made for (and in duet form, replicated) great conversation, even if it was often apparent that the man behind so many secular hymns of desire—requited and otherwise—was talking to himself. To the extent that Hart was a public figure, portrayed posthumously by Mickey Rooney in 1948’s Words and Music , the MGM hit mythologizing his