Herodotus tells the story as recent history, not legend. Before the battle of Marathon in 490 BCE, the Athenians sent the long-distance runner Pheidippides to Sparta for help. On Mount Parthenion near Tegea, he said, Pan called him by name and asked why the Athenians paid him no attention, when he had been good to them before and would be again. Athens believed him. After the battle they established a sanctuary in a cave on the north-west slope of the Acropolis and instituted annual sacrifices and a torch race.
That is a documented state cult founded because of a reported roadside encounter with a goat-god, in a city that would shortly build the Parthenon. It is also the reason Pan is credited with the enemy's rout: the sudden irrational terror that empties a battle line is his, and the Greek word for it is panikon, from his name.
Arcadian, and older than his mythology
His homeland is Arcadia, the mountainous, poor, pastoral interior of the Peloponnese, and his oldest cult is there: on Mount Lykaion, at Berekla, in caves throughout the region. He is a herdsman's god of a herdsman's country, and Arcadian shepherds were reported to whip his statue when the hunting was bad — one of very few instances of a Greek deity being punished for underperformance.
Homeric Hymn 19 tells his birth: Hermes, serving as a mortal's herdsman, fathers him on a nymph, and the nurse runs away in fright at the goat-footed, bearded, laughing baby. Hermes wraps him in hare-skins and carries him to Olympus, where all the gods are delighted, and Dionysus most of all. The etymology the hymn gives — that he was called Pan because he pleased all of them — is folk etymology; his name more likely comes from a root meaning to pasture, related to Latin pastor, which fits his function exactly.
The all-encompassing "Pan = the All" reading was taken up seriously by Stoic and later Neoplatonic allegorists and became enormously influential in the Renaissance, when Pan-as-universe appears in mythographies and emblem books. It is a pun with a long career.
Noon, caves and the pipes
He sleeps at midday and it is dangerous to disturb him, which makes him one of the few gods associated with a specific hour. His haunts are caves — dozens of Greek cave sanctuaries are his, often shared with the Nymphs, and cave cult is his characteristic setting rather than a temple.
The syrinx, the panpipe, comes with an aetiology told most fully by Ovid: the nymph Syrinx, fleeing him, was turned into marsh reeds at the river Ladon, and when he grasped at her his sigh through the hollow stems made a sound he could not bear to lose, so he cut them into unequal lengths and bound them. Ovid embeds it as a story-within-a-story that Hermes is telling to bore Argos to sleep, and then breaks off mid-telling — the joke being that Argos has nodded off before the end. Another pursuit produces Echo, torn apart in some versions and surviving only as a voice; another, Pitys, becomes the pine, which is why he wears a pine wreath.
The strangest death notice in ancient literature
Plutarch, in On the Obsolescence of Oracles, reports a story he says was told by a reliable witness. A ship becalmed off Paxi at evening heard a voice calling the Egyptian pilot by name — Thamus — three times, and instructing him that when he reached Palodes he should announce that Great Pan is dead. He did, and there was a great groaning and lamentation from the shore.
Christian writers from Eusebius onward read this as marking the moment paganism died, and the fact that Tiberius' reign brackets the crucifixion made the reading irresistible. It runs through Rabelais, Milton, Elizabeth Barrett Browning and Nietzsche. The scholarly counter-proposal is that the sailors misheard a ritual cry — Thamous panmegas tethnēke, or a lament for Tammuz, the Near Eastern god whose annual mourning was a public rite — and turned a seasonal wailing into a divine obituary. Neither reading can be proved, and Plutarch himself reports it as a curiosity rather than a doctrine.
From goat-god to devil to horned god
Medieval Christian iconography assembled the devil from several sources, and Pan and the satyrs supplied a large share of the visual vocabulary: goat legs, horns, cloven hooves, body hair, unrestrained appetite. The equation was made polemically by early Christian writers who classed the old rural gods as demons, and the imagery outlasted the argument.
Then it reversed. Nineteenth-century writers made him the emblem of a lost natural world — the whole Romantic and Edwardian "Great God Pan" tradition, from Shelley and Keats through Arthur Machen's disturbing 1894 novella to the chapter "The Piper at the Gates of Dawn" in The Wind in the Willows, where he appears as a vision of overwhelming benign holiness. Peter Pan takes the name and the pipes and the refusal to grow up. In the twentieth century, Wicca and modern paganism adopted a Horned God who owes as much to Pan and to Margaret Murray's now-discredited witch-cult theory as to any Celtic figure.
Very few ancient gods have been a demon and a nature-spirit and a children's character, and it is all the same set of goat legs.
One Pan or a great many, and where they were actually worshipped
Is he one god or many?
Both, and unusually so. Later authors speak of Panes in the plural, a whole class of goat-legged rustic spirits alongside satyrs and sileni, and vase painting shows groups of them. The slippage between a single named god and a category of beings is rare among Olympians and normal among rural powers, which is a good indication of the level of religion he belongs to.
What is his connection to Dionysus?
He is a regular member of the Dionysiac retinue in art and poetry from the Hellenistic period, dancing with satyrs and maenads, and the Homeric Hymn already says Dionysus was the most pleased at his arrival. The two overlap in wildness, in the countryside, in music, and in the capacity to induce states people do not choose. But his cult is older and separate, and Arcadian Pan has nothing to do with wine.
Did the Romans have a version?
They identified him with Faunus, an Italian woodland and prophecy god, and with the plural fauni; the Lupercalia, with its runners in goatskin striking bystanders with thongs, was connected to the same complex. Faunus has his own oracular function — he speaks in dreams in sacred groves — which Pan does not, and the identification is another of the loose equations that flatten two different gods into one entry in a table.
What was the Corycian cave?
A large cave high on Parnassus above Delphi, sacred to Pan and the Nymphs, and one of the best-excavated cult caves in Greece: it produced tens of thousands of votive objects, including over twenty thousand astragals — knucklebones — used for gaming and divination. It is a concrete picture of what worshipping him actually involved, and it is nothing like a temple.