Tragedy is not an imitation of persons, but of actions and of life. Well-being and ill-being reside in actions, and the goal of life is an activity, not a quality; people possess certain qualities in accordance with their character, but they achieve well-being or its opposite on the basis of how they fare. So the imitation of a character is not the purpose of what the agents do; character is included along with and on account of the actions. So the events, i.e. the plot, are what tragedy is there for, and that is the most important thing of all.