|(Level 1) Educator Emeritus
There were three unities called for in tragedy, unity of time (24-hour period), unity of action (one story only), and unity of place, by which is meant the drama cannot change venues. For example, in Oedipus, the action all takes place before the palace; it does not go inside, or to Jocasa's bedroom, or to another part of the kingdom. The only “spectacle” or “scenery" were pereoktoi, two tall thin prisms with three sides, which could be rotated to signify change of scenery. These were “ex post facto” rules – observations of Aristotle after seeing the tragedies of Aeschylus, Sophocles, and Euripedes, -- so not exactly prescriptive, but rather descriptive. Plot developments such as the discovery of Oedipus on the mountainside or his actual confrontation with his father at the crossroads were not staged but described by a character in front of the palace.