In ancient Greece, the stranger knocking at your door was under Zeus’s protection. Literally: one of his titles was Zeus Xenios, “Zeus of strangers”. Treat a guest badly and you’ve offended the king of the gods.
The rule is called xenia, sacred hospitality, and it works both ways.
The host: welcome the stranger without questions. First a bath, clean clothes, a seat, food and wine; only then ask who they are and what they want. And when they leave, gifts, and help to go on their way.
The guest: respect the house, its people and its things. Don’t abuse it, don’t overstay. The bond is hereditary: in The Iliad, the Greek Diomedes and the Trojan Glaucus are about to kill each other when they discover their grandfathers were host and guest. They stop fighting and swap armour.
Why so serious? Because any beggar could be a god in disguise, testing you. Athena walks into Telemachus’ house dressed as a stranger. In Ovid, an old couple, Baucis and Philemon, are the only ones in town who take in two travellers: Zeus and Hermes, in disguise. They’re the ones who survive.
And the big breaches of xenia drive both epics:
- Helen leaving Menelaus’ house with Paris, his guest: that betrayal of hospitality is what starts the Trojan War.
- The Cyclops Polyphemus, instead of feeding his guests, eats them.
- Penelope’s suitors spend years eating up Odysseus’ house, and mistreat the beggar who shows up, who is Odysseus in disguise. The massacre at the end is, among other things, the punishment for breaking xenia.
- And the good example: the Phaeacians, who take in a shipwrecked stranger before knowing who he is, and sail him home.
You can read the whole of The Odyssey as a catalogue of good and bad hosts.