“A war. A man. A trick. A trick to break the walls of Troy. And burn it—screaming—to the ground.” Christopher Nolan’s The Odyssey opens in the great hall of Ithaca, with a bard singing a hymn about the cunning of Odysseus, the hero of the tale, to the men who have overrun his house—courting his wife, menacing his son—while he is absent. A feast has been turned into a desecration.

The law these men broke was the most sacred in the ancient world: “xenia,” the law of hospitality. The stranger at the door stood under the personal protection of Zeus, the greatest of the gods and the protector of strangers. The bond between guest and host was not mere courtesy; it was the covenant that made trust between strangers possible.

In the Bronze Age, that covenant was foundational. Greece was not a nation; it was a scattering of city-states and island kingdoms with no common law and no shared authority. Travelers had no rights. Xenia was the guarantee that allowed strangers—hosts and guests, both with reciprocal obligations—to trust one another. It was the thread that held a fractured world together.

“Break Zeus’s law and see what they do to you if you give them that excuse,” Penelope, the wife of Odysseus, says to her son Telemachus. And in the movie, Telemachus says that one must always be generous to travelers, because they might secretly be gods in disguise. To mistreat strangers is to risk incurring the wrath of the gods.

The Trojan War began with a breach of hospitality. Paris, a son of the Trojan king, was welcomed as a guest into the Spartan home of King Menelaus—and repaid that welcome by running off with Menelaus’s wife, Helen, said to be the most beautiful woman in the world. Menelaus’s brother, Agamemnon, led a Greek expedition to bring her back. The war lasted 10 years, ending when the Greeks at last sacked Troy by the ruse of the Trojan horse.

[Read: Odysseus’s confession]

The ruse was Odysseus’s idea, a stroke of military genius for which he was celebrated. But in Nolan’s telling, it is not a triumph but a moral failure, one that fills him with such guilt and shame that for a decade he cannot go home. He had turned something sacred into a weapon. The horse was disguised as a holy offering to Athena; the Trojans, afraid to offend the goddess, wheeled it inside their own walls. Once the gates were open, the Greeks spilled out and slaughtered the city.

In the film, unlike the poem, that massacre shadows Odysseus, though we do not understand just how much so until the end. Throughout his journey he is accompanied by Athena, the goddess of wisdom. Only when the film returns to the night Troy fell do we realize she wears the features of a priestess of Athena, beheaded at the goddess’s own altar as the city burned. Odysseus’s divine mentor, the guide who has walked beside him all along, bears the features of a woman he watched die. Whether a goddess ever accompanied him, or whether she is only the ghost of his greatest sin, the film leaves uncertain. What is certain is that until Odysseus can face what he has done, until he tells the truth about himself to himself, and to others, no homecoming is possible.

In the film’s closing stretch, Odysseus returns to Ithaca disguised as a beggar and sees what his world has become. Law and order are collapsing; trust is nonexistent; scheming is rife. The man who once commanded armies discovers how men behave toward someone who can do nothing for them. The only kindness he receives comes from his son and a few loyal servants. Then, near the end of the film, Odysseus says to Penelope, “We are the people from the sea,” by which he means the dreaded outsiders, raiders, and marauders. But they were not the threat after all. The “people from the sea” are the victors of the Trojan War, stripped of their humanity, their civility, their xenia.

Telemachus was not alone in his intuition about gods in disguise. The conviction that the stranger at your door may be more than he appears runs through the Hebrew and Christian scriptures too. When, in Genesis, Abraham looks up at Mamre and sees three travelers, he runs to meet them, washes their feet, and sets a meal before them—not knowing, as the reader does, that he is entertaining the Lord. The letter to the Hebrews tells us to show hospitality to strangers, for some have “entertained angels unawares.” And in Matthew 25, the stranger is Christ himself. “I was a stranger and you welcomed me,” Jesus says. What he is revealing is that the stranger is where God has chosen to be found, and that every person will be judged by how they treat the outcast, the hungry, the sick, the beggar at our door.

Homer’s poem, like the Hebrew scriptures and the New Testament, is an ancient text. But as Nolan told The New York Times, the greatness of the poem is that you approach it as something foreign and remote, and then find it “stunningly relevant.” On the treatment of the stranger, he added, nothing has changed—it remains essential to “holding civilization together, or even defining civilization.”

Part of what makes The Odyssey so appealing to a modern audience is that it takes civilizing aspects of Greek culture—hospitality and magnanimity—and adds later concepts, some of them influenced by Jewish and Christian ethics that were, to varying degrees, alien to ancient Greek culture: deep introspection, even confession; humility and empathy; sorrow and guilt for the harm one has done, even in victory; the conviction that the conquered count and have worth; and vengeance tempered with mercy. In the film, Odysseus emerges as a figure haunted by his victory in a way that no ancient Greek would have been.  

The Odyssey presents a very human hero to a culture that desperately needs one. Nolan could have told this story several different ways, but he trusted his instinct: A summer audience would embrace an epic story and its complicated hero, brave but broken, fierce but tender toward the weak, a person we admire not so much for his battlefield victories as for his conscience.   

[Read: The Odyssey was never about the gods]

Much of life in the ancient Greek world was harsh, even barbarous—mass executions in conquered cities, torture, the weak discarded at birth, chattel slavery—which is precisely why the Greek commitment to honor and hospitality was remarkable then and still resonates today. So, too, do the later, more humane virtues the film weaves in.

Those virtues are now under assault. Movements and voices in our own country hold them in open contempt, treat mercy as weakness, and feed on vengeance and grievance. Theirs is a Nietzschean ethic, a “master morality,” the code of the strong that Christianity overthrew when it took the side of the slave, the stranger, and the destitute.

But Nietzsche was at least honest about the cost of the revolution he heralded. With God dead, he warned, the morality built on God might collapse as well, and into the gap meaninglessness, fanaticism, and substitute faiths could rush in. Nietzsche declared, with some sorrow, the death of God. Many of his heirs gleefully practice their cruelty in God’s name.

The world that this ethic is creating is harsh and barren, raw and uninviting. It exists in the daily coarseness, in the anger and the ugliness, and in the isolation. There is a weariness in us, and a sadness, at what we have become. Robert F. Kennedy, citing the classicist Edith Hamilton, once issued this call: “Let us dedicate ourselves to what the ancient Greeks wrote so many years ago: ‘to tame the savageness of man and make gentle the life of this world.’” What Christopher Nolan and his cast have tapped into is our longing for a gentler world. We want to go home.