In his book, "The Poetics," Aristotle expresses some of his thoughts about the merging of literature with tragedy. Tragedy is an imitation of an action that is serious, complete, and of a certain magnitude. Every Tragedy, therefore, must have six parts namely, Plot, Characters, Diction, Thought, Spectacle and Melody. Tragedy is the "imitation of an action" (mimesis) according to "the law of probability or necessity." Aristotle indicates that tragedy "shows" rather than "tells." Tragedy arouses the feelings of pity and fear. Aristotle was a great admirer of Sophocles' 'King Oedipus'. He considered it as the perfect tragedy. Plot is the most important feature of tragedy. Aristotle defines plot as "the arrangement of the incidents." Tragedies which have a tightly constructed cause-and-effect chain of actions are superior to those which depend on the character and personality of the protagonist. The plot must be "complete," having "unity of action." The plot may be either simple or complex, although complex is better. .
Simple plots have only a "change of fortune" (catastrophe). Complex plots have both "reversal of situation" (peripeteia) and "recognition" (anagnorisis) connected with the catastrophe. Both peripeteia and anagnorisis turn upon surprise. Peripeteia leads directly to the anagnorisis. This creates the catastrophe, leading to the final "scene of suffering". .
Characters in a tragedy are also very important. In a perfect tragedy, character supports plot. The protagonist should be renowned, so his 'change of fortune' can be from good to bad. This change should come due to some 'tragic flaw' in his character. For example, in Hamlet, the hero is kind, thoughtful, gentle and cultured. But he is weak and indecisive, which leads to his tragedy. Such a plot is most likely to generate pity and fear in the audience.