Lanthimos's film reworks the sacrifice of Iphigenia, a father forced to kill one of his own children, and the play is named in the film through the daughter's school essay.
Play· -405· Tragedy
by Εὐριπίδης Euripides
Ἰφιγένεια ἐν Αὐλίδι (Iphigenia in Aulis): 1 recorded work traces back to it, and it draws on 1 recorded source.
Works that record this one as a source, with the evidence a contributor gave.
Events, places, movements and ideas outside fiction that this work is recorded as drawing on.
Real world
Euripides stages the myth of Agamemnon sacrificing his daughter Iphigenia at Aulis so the Greek fleet can sail for Troy.