There are four key things to remember about the film: it is not intended to be Herodotus Book 7.209-236, but rather is an adaptation from Frank Miller’s graphic novel, which itself is an adaptation from secondary work on Thermopylai. Purists should remember that when they see elephants and a rhinoceros or scant mention of the role of those wonderful Thespians who died in greater numbers than the Spartans at Thermopylai.Second, in an eerie way, the film captures the spirit of Greek fictive arts themselves. Snyder and Johnstad and Miller are Hellenic in this sense: red-figure vase painting especially idealized Greek hoplites through “heroic nudity”. Such iconographic stylization meant sometimes that armor was not included in order to emphasize the male physique.
So too the 300 fight in the film bare-chested. In that sense, their oversized torsos resemble not only comic heroes, but something of the way that Greeks themselves saw their own warriors in pictures. And even the loose adaptation of events reminds me of Greek tragedy, in which an Electra, Iphigeneia or Helen in the hands of a Euripides is portrayed sometimes almost surrealistically, or at least far differently from the main narrative of the Trojan War, followed by the more standard Aeschylus, Sophocles and others.
Third, Snyder, Johnstad, and Miller have created a strange convention of digital backlot and computer animation, reminiscent of the comic book mix of Sin City. That too is sort of like the conventions of Attic tragedy in which myths were presented only through elaborate protocols that came at the expense of realism (three male actors on the stage, masks, dialogue in iambs, with elaborate choral meters, violence off stage, 1000-1600 lines long, etc.).
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Fourth, but what was not conventionalized was the martial spirit of Sparta that comes through the film. Many of the most famous lines in the film come directly either from Herodotus or Plutarch’s Moralia, and they capture well, in the historical sense, the collective Spartan martial ethic, honor, glory, and ancestor reverence (I say that as an admirer of democratic Thebes and its destruction of Sparta’s system of Messenian helotage in 369 BC).