Performance of tragedy was tied up with the festivities of the Great Dionysia in Athens. A play competiton was staged during the three days of the festival (during March or April). Later, plays were also performed during the Lenea, another Dionysian holiday celebrated in January or February. All the plays were staged in a sanctuary of Dionysos, with the usual format being an inter-related tragic trilogy followed by a farce known as the satyr play.

Why was tragedy associated with the cult of Dionysos? No one has put forward a definite explanation. The meter of tragic poetry (the dithyramb) was first employed in hymns or songs connected with poetry of Dionysos cult, and was used chiefly in processional and choral lyrics with narrative themes. Poets had treated heroic subjects in this meter from the 7th century BCE. Choral lyrics were also written in the Dorian dialect -- the same dialect used in the "songs" chanted by the Chorus in tragedy.

Fritz Graf has argued that as the Athenian tragedians flourished in the 5th century BCE, their art necessitated a different perspective on the relationship between men and gods (Graf, see discussion of Euripides 170-175). Gods, like men, could be represented in the flesh -- the physical distance between man and god collapses, as does the temporal distance between a present and a heroic age. The contrast between men and gods shed valuable light on the human condition, and so myths became an important source for tragedies. Even Aeschylus acknowledged Homer's importance for tragedians, however; one could say that they were not diverging from his portrayals of gods and men, but developing it for their own era.

Yet by the 5th century BCE, the mythological traditions had solidified. Tragedians could bring a modern perspective to a myth, and their emphases revealed their personal artistic concerns, or the cultural trends of Athens as a whole. Aeschylus, in the Orestia, contrasts the primordial version of justice (erinyes and a blood feud) with the Athenian Areopagus, or court of appeal. Sophocles creates tragedies in which man is doomed by the inexorable justice of the gods. Euripides, like Sopholes, is writing during the Athenian-Spartan war; however, he uses many exotic variants of famous legends to portray fantastic elements of the relationship between human and divine.

Sources:
Fritz Graf, Greek Mythology: An Introduction. Trans. Thomas Marier (Baltimore: Johns Hopkins Univ. Press, 1993).

Peter Levi, "Greek Drama" in The Oxford Hisory of the Classical World, ed. John Boardman, Jasper Griffin, and Oswyn Murray (Oxford: Oxford Univ, Press, 1986)