The word
Mētis is practical intelligence: the capacity to find a way through a situation that force cannot solve. It covers cunning, resourcefulness, timing, disguise, calculation and deceit, and Greek thought treats it as a single faculty rather than as a set of separate virtues and vices.
It is opposed to biē, force. The Iliadic hero has biē; Odysseus has mētis; the poems know the contrast and use it. Achilles hates the man who says one thing and hides another in his heart. Odysseus does it constantly.
Metis is also a person: in Hesiod, a Titaness, the first wife of Zeus, whom he swallows while pregnant so that no child of hers may overthrow him — and Athena is the child, born from his head. The goddess of cunning intelligence is cunning intelligence, absorbed and made safe.
Mētis in the Odyssey
The poem's fullest demonstration is the Cyclops. Trapped behind a stone no man can move, Odysseus cannot fight his way out — killing Polyphemus would seal them in. He therefore solves a physical problem with a linguistic one: he gives his name as Outis, Nobody, so that the victim's cry for help defeats itself.
The Greek doubles the point in a way no translation carries. Outis means nobody; mē tis, the other way of saying no one, is a homophone of mētis. Odysseus escapes by being nobody and by being cunning, in the same sound.
Elsewhere: the wooden horse, recalled twice in the poem; the false Cretan life stories told to Athena, Eumaeus, Penelope and Laertes; the contest of the bow, which is arranged by his wife and which is the last and best trick in the poem.
Penelope has it too
The shroud is mētis. Penelope takes an obligation the suitors cannot refuse — the duty owed to the dead — and turns it into three years of delay. The test of the bed is mētis: she provokes her husband into revealing himself by insulting his workmanship, and it is the only time in the poem anyone outmanoeuvres him.
The poem's word for what makes their marriage good is homophrosynē, like-mindedness. It is not affection. It is two people with the same faculty recognising each other.
Why it is morally unstable
Mētis has no fixed moral sign, and the Greeks did not pretend otherwise. The same faculty that saves the crew from the cave is the faculty that lies to a grieving father in an orchard for no reason.
The tradition split accordingly. The Cynics and Stoics made Odysseus a model of rational self-command. Attic tragedy made him a manipulator — Sophocles' Philoctetes has him arguing for deceit against a young man's scruples. Virgil, writing from the Trojan side, made him a deviser of crimes. Dante put him among the counsellors of fraud.
None of these is a misreading. They are different weightings of a faculty the poem itself presents without a verdict.
Later interpretation
The modern scholarly treatment that made mētis a category in its own right is Marcel Detienne and Jean-Pierre Vernant's Les ruses de l'intelligence: la mētis des Grecs (1974), which traced it across Greek thought from Homer to the sophists. It remains the standard starting point.