EPISODE, an incident occurring in the history of a nation, an institution or an individual, especially with the significance of being an interruption of an ordered course of events, an irrelevance. The word is derived from a word (?πε?σοδος) with a technical meaning in the ancient Greek tragedy. It is defined by Aristotle (Poetics, 12) as μ?ρος ?λον τραγ?δ?ας τ? μεταξ? ?λων χορικ?ν μελ?ν, all the scenes, that is, which fall between the choric songs. ε?σοδος, or entrance, is generally applied to the entrance of the chorus, but the reference may be to that of the actors at the close of the choric songs. In the early Greek tragedy the parts which were spoken by the actors were considered of subsidiary importance to those sung by the chorus, and it is from this aspect that the meaning of the word, as something which breaks off the course of events, is derived.