| In ancient Greece, drama was an important part of certain religious festivals. At Athens, for example, a festival was held every spring in honor of Dionysus, with a drama competition lasting three days, at the end of which prizes were awarded. At the City Dionysia festival, also in Athens, three poets entered four plays each, three tragedies and a satyr play. Comedies were also staged, and here, as in tragedy, the chorus of dancers and singers was an important element. However, in tragedy, the chorus gradually became smaller, and innovations were made by the great playwrights: Aeschylus introduced a second actor and Sophocles a third, while Euripides in some of his plays virtually reduced the chorus from its central role to simply an interlude.
The origins of tragedy are not clear, but it perhaps emerged from a combination of lyric poetry and Dionysiac ritual. However, although it retained a religious link in its association with the Dionysus festival, it was not ritual drama. The greatest dramatists, Aeschylus, Sophocles, and Euripides, were all Athenians and spanned the fifth century. Of the 300 plays they wrote, only about a tenth survive; no plays by the other 150 known writers of tragedy have been found. The great creative period of this genre was partly the result of the situation in fifth-century Athens; for all its faults, the Athenian political system created a world in which the dramatist could write free of constraints except for those imposed by the medium itself.
Tragedies explored the human soul and were often concerned with moral issues related to the affairs of the city-state. In The Persians by Aeschylus, presented only ten years after the Greco-Persian War, the central theme is the establishment of Athenian liberty. More profound is the same playwright's Orestian trilogy. He takes as his starting point the murder of Agamemnon by his wife Clytemnestra and traces the consequent blood feud and its final resolution through the introduction of law. Themes such as this are universal, and it is hardly surprising that the tragedies of Aeschylus and his succesors, Sophocles and Euripides, continue to be produced more than 2,000 years after they were written. | 
