That unfunny dramatic theorist, Aristotle, probably would have loathed the idea that the high point of the Central City Opera's production of Dialogues of the Carmelites occurred in Act One, long before a proper "rising action" developed. Even so, audiences appreciated the fact that mezzo-soprano Joyce Castle marvelously commanded the stage as a venerable abbess. The regal singer conferred an authority on Francis Poulenc's opera and left one admiring a beauty too terrible to embrace yet too compelling to disregard. Even Aristotle would probably approve of that.