The use of the name Jupiter instead of Zeus is important here. Most English translations use the name Zeus throughout. In the French original, however, Sartre makes only one mention of Zeus, in Act II when Orestes asks for moral guidance. Zeus and Jupiter are the Greek and Roman names for the same god, respectively. In Aeschylus's original Greek text, the name Zeus is used, and there Zeus is seen as the arbiter of Good and Evil, since divine justice is supreme in Greek myth. Sartre intentionally departs from this view of the god, introducing him in the stage directions as the "god of flies and death." Sartre's main goal in the play is to show that human freedom is of greater value than the justice of the gods. By referring to Jupiter instead of Zeus he attempts to do away with the conception of Zeus as the highest judge of Goodness.
The flies are introduced almost from the start, and Jupiter himself tells us that they are a symbol. The flies came to the city after Agamemnon's murder, and they serve as a reminder of the Argives's need to repent. By biting the people, the flies emphasize the importance of punishment in atoning for one's sins. Jupiter mentions that the flies were attracted by the smell of carrion and have stayed in the city ever since and grown larger. Their continued presence shows that death has never left Argos. The city has been dead for fifteen years.
Sartre suggests that religion is a source of repressive morality. The old woman whom Jupiter interrogates mentions that her grandson "never plays or laughs, for thinking of his original sin." This is an allusion to the original sin of Judeo- Christian religion, where the original sin of eating the forbidden apple results in a collective human guilt. Christ frees us from the original sin, and there is a suggestion that Orestes plays an analogous role. Sartre's intention is not to make Orestes a religious figure, but rather to show that Orestes's human action and human values can supplant divine action and divine values. Orestes is meant to replace Christ, not imitate him.
Jupiter's trick to make the flies fall down is a recurring comedic motif throughout the play. Jupiter waves his arm and says "galla, galla, tsay, tsay," making him appear ridiculous rather than terrifying. Jupiter's power throughout consists of trifling tricks carried out with silly invocations and arm movements. By reducing the god's divine power to farce, Sartre undermines our respect for religious authority and the moral pronouncements it passes down to us.
In the dialogues of Jupiter and the Tutor, the first half of Act I brings out the two most significant challenges to true freedom. Jupiter makes a twofold claim. First, strangers have no place interfering in the affairs of Argos. Second, divine justice is the highest value. Jupiter emphasizes that he did not interfere in Agamemnon's murder because he was only a visitor to the city. It was not his place to intervene. He warns Orestes to leave Argos for the same reason. Orestes did not grow up in Argos, he does not share the guilt of its people, and he has no right to get in the way of their repentance. Guilt makes the Argives pious. Their fear and repentance keep them from enjoying life and from challenging the established order of their society. The gods take pleasure in the wretchedness of the Argives, and so this lifestyle should not be disturbed. Jupiter urges Orestes to leave Argos unchanged because it is not his place to change it and because he must not violate the justice of the gods.
The Tutor agrees with Jupiter that Orestes should leave Argos, though for different reasons. The Tutor has taught Orestes that human morals are variable, and that none of them are to be trusted. He rejects religious morals because he rejects all morals. Unlike Jupiter, who argues that one should avoid drastic action because action will upset divine justice, the Tutor argues that one should avoid drastic action because there is no reason to act. "You know better than to commit yourself—and there lies your strength," the Tutor tells Orestes. The Tutor agrees that Orestes should not attempt to change Argos because he is a stranger, but he believes that being a stranger is a strength rather than a weakness. By keeping aloof and maintaining no connection with any people, Orestes leaves himself free to do anything he wants. Human society, the Tutor believes, only serves to limit one's freedom. If Orestes is to act, then, he must reject both the order of the gods and the Tutor's false notion of freedom.