The importance of freedom is the dominant theme of the play. Sartre's philosophy is built around the idea that human beings are capable of interpreting the world for themselves, thereby creating new values. Freedom is this ability to invent new values and to create oneself and one's own world. Since all other values spring from one's free interpretation of the world, freedom is the foundational value in Sartre's system. Finding the people of Argos enslaved by a moral framework that requires perpetual repentance for past sins, Orestes decides that he must create himself and his world by murdering Aegistheus and Clytemnestra in order to establish himself as one of the Argives and also to set the Argives free from these tyrannical rulers. Since human freedom is the greatest value, it supercedes both the skeptical view that all morals are relative and the god-given moral norm to which all human beings must adhere. Orestes makes his decision to act by freeing himself both of the idea of destiny and of Jupiter's attempts to maintain order. For Sartre, freedom involves both a choice and an action based on that choice; the play is structured around this view of freedom. Act II, the only act with two scenes, shows Orestes making his decision in Scene One and acting upon that decision in Scene Two. Orestes's realization of his freedom thus provides an axis around which the action of the play revolves. Since Sartre wrote The Flies during the Nazi occupation of France, he preaches violent and revolutionary action that frees people from a moral system imposed on them from above.
Responsibility can be related either to guilt or to freedom. To take responsibility for an action may mean to feel guilty about it. The Argives are taught that they are responsible for their sins and must spend their lives repenting of those sins. Orestes flips this view of responsibility around, insisting that one incurs guilt only when one refuses responsibility for an action and repents. Guilt occurs when an individual judges his or her action to be wrong according to the moral norm. Since the highest moral values stream directly from human freedom, one cannot incur guilt if one acts freely. The free actions taken by individuals create their values, so that a free action cannot be wrong according to the agent's moral standards. Orestes takes full responsibility for the murder of Aegistheus and Clytemnestra. As a result, he feels that his action was right since he acted in accordance with his free decision. Electra refuses to take responsibility for the murders because she is afraid of how others will judge her. She refuses responsibility for her part in the murder, so that her participation becomes more of an accident than a human action. Electra is tormented by guilt precisely because she refuses to accept her action as her own and attempts to place all the responsibility on Orestes. As a result she feels that it is he who ruined her innocence.
Free action requires an engagement with the future. The Argives are not free because they look only towards their past and the sins they have committed. They are incapable of freely shaping their lives because the burden of their past keeps them from creating new values. Their values are set in stone, and their lives consist of judging the same old sins by the same old moral standards. In order to act freely, one must interpret one's past instead of letting an interpretation be imposed by someone else. Orestes, the only free character in the play, acts in order to create himself; he acts for the sake of his future. Electra, on the other hand, acts out of revenge for the past. She looks ahead to only one event in her future: her bloody vengeance. Once this event has occurred, Electra can only look backwards and cannot recognize her freedom.
Orestes feels light before he acts because he has not yet shaped himself. He complains that he is light as air because he has no home, no real character. He has not yet invented his own values and given a meaning to his life, so that he feels like a ghost or a shadow. Once he commits his murder, he attaches himself to his action. His life takes on a meaning that he himself has given it through his own free choice. This meaning makes him heavy, and Electra comments on how heavy his hand became in order to strike down Aegistheus. Before the murder, Orestes lacks content: he is just like any object, being acted upon and acting without responsibility. After the murder, he has shaped himself, and thus bears the weight of responsibility for his action.
Sartre directs his satirical wit towards ridiculing authority figures. Jupiter shows his powers by waving his hand and speaking nonsense. He creeps around on tiptoe to eavesdrop on conversations. To demonstrate his greatness, he lapses into silly melodrama. When Jupiter and Aegistheus meet, Jupiter makes fun of Aegistheus's tone of voice and perpetual complaining, while Aegistheus sarcastically rejects Jupiter's claims that he is terrifying and awe inspiring. A scene directly in the middle of the play shows two soldiers in the throne room asking each other absurd questions about ghost flies and whether the ghost of Agamemnon is as fat as he was while alive. The scene is intended to lighten the solemnity of the king's seat of power. Throughout the play Sartre relies on humor to suggest that all power over others is grounded on a farce.
Eyes have three symbolic meanings in the play. First, eyes are symbols of the vision needed to see the future. With the initial exception of Electra, all the Argives have "dead" eyes because they can only look towards the sins of their past. Orestes's eyes are bright because he looks ahead towards the future, unhampered by his past. Second, eyes symbolize judgment. Electra is afraid of how others will judge her. As a result, she always notices everyone's eyes. In Argos, where every person expects to be observed and judged by his or her neighbor, everyone fears the eyes of others. Those who cannot freely impart meaning on their lives allow others to interpret their lives for them through the judgment in their eyes. The looks of others enslave us if we allow others to impose their moral standards on us. Jupiter, whenever he gives someone an order, forces that person to look him in the eyes: as the supreme judge, he controls human beings with his eyes, the symbols of judgment. Third, the symbolism of eyes reminds the audience that it is watching, with its eyes, a dramatic performance, and this conscious reminder of vision suggests that it is possible to go beyond the purely visual presentation of the play and to put the play's values into action in real life.
Stones recur repeatedly throughout the play. They are symbols of nature. Unlike human beings, who have the freedom to give meaning to their lives, stones are inanimate objects that have no meaning until someone imposes meaning on them. Jupiter has powers over nature and twice demonstrates his power over stones, first when he causes a stone to roll away from the cave of the dead to silence Electra and then again when he causes light to flash around the stone in response to Orestes's request for a sign. Since Jupiter can only control stones but not people, he seeks to reduce all human beings to the level of stones. He wants to impose order on humanity that will allow him to impose meaning on human beings from above. So long as people fear him, he has power over them because they worry only about how he interprets their actions. Stones are a contrast to human existence, but human beings can also be reduced to stones.
The flies were sent to Argos by the gods fifteen years before the action of the play when Aegistheus and Clytemnestra murdered Agamemnon. The flies serve as a perpetual reminder of this original sin, biting the Argives to help them repent. When Orestes and Electra kill their mother and the king, the flies turn into the Furies, the goddesses of remorse. The Furies live to punish sinners, but they have power only over those who feel remorse for their actions. Orestes is immune to the power of the Furies. Electra, on the other hand, willingly surrenders herself to them when they promise that the physical pain they cause her will make it easier for her to tolerate her repentance.