The genre of tragedy is rooted in the Greek dramas of Aeschylus (525-456 B.C., e.g. the Oresteia and Prometheus Bound), Euripides (ca. 480?-405 B.C., e.g. Medea and The Trojan Women) and Sophocles (496-406 B.C., e.g. Oedipus Rex and Antigone). One of the earliest works of literary criticism, the Poetics of the Greekphilosopher Aristotle (384-322 B.C.), includes a discussion of tragedy based in part upon the plays of Aeschylus, Euripides, and Sophocles. While Shakespeare probably did not know Greek tragedy directly, he would have been familiar with the Latin adaptations of Greek drama by the Roman (i.e. Latin-language) playwright Seneca (ca. 3 B.C.-65 A.D.; his nine tragedies include a Medea and an Oedipus). Both Senecan and Renaissance tragedy were influenced by the theory of tragedy found in Aristotle's Poetics.
Classical Tragedy: According to Aristotle's Poetics, tragedy involves a protagonist of high estate ("better than we") who falls from prosperity to misery through a series of reversals and discoveries as a result of a "tragic flaw," generally an error caused by human frailty. Aside from this initial moral weakness or error, the protagonist is basically a good person: for Aristotle, the downfall of an evil protagonist is not tragic (Macbeth would not qualify). In Aristotelian tragedy, the action (or fable) generally involves revolution (unanticipated reversals of what is expected to occur) and discovery (in which the protagonists and audience learn something that had been hidden). The third part of the fable, disasters, includes all destructive actions, deaths, etc. Tragedy evokes pity and fear in the audience, leading finally to catharsis (the purgation of these passions).
Medieval tragedy: A narrative (not a play) concerning how a person falls from high to low estate as the Goddess Fortune spins her wheel. In the middle ages, there was no "tragic" theater per se; medieval theater in England was primarily liturgical drama, which developed in the later middle ages (15th century) as a way of teaching scripture to the illiterate (mystery plays) or of reminding them to be prepared for death and God's Judgment (morality plays). Medieval "tragedy" was found not in the theater but in collections of stories illustrating the falls of great men (e.g. Boccacio's Falls of Illustrious Men, Chaucer's Monk's Tale from the Canterbury Tales, and Lydgate's Falls of Princes). These narratives owe their conception of Fortune in part to the Latin tragedies of Seneca, in which Fortune and her wheel play a prominent role.
Renaissance tragedy derives less from medieval tragedy (which randomly occurs as Fortune spins her wheel) than from the Aristotelian notion of the tragic flaw, a moral weakness or human error that causes the protagonist's downfall. Unlike classical tragedy, however, it tends to include subplots and comic relief. From Seneca, early Renaissance tragedy borrowed the "violent and bloody plots, resounding rhetorical speeches, the frequent use of ghosts . . . and sometimes the five-act structure" (Norton Anthology of English Literature, 6th ed., vol. I, p. 410). In his greatest tragedies (e.g. Hamlet, Othello, King Lear and Macbeth), Shakespeare transcends the conventions of Renaissance tragedy, imbuing his plays with a timeless universality.