River Styx

Styx was born the eldest of the Oceanids, the three thousand water nymphs of Oceanus, the river that rings the world, and his sister-queen Tethys. Her name comes from stygein, to hate and to shudder, and she was the river of abhorrence made divine, the cold black water that the whole world dreads. In the deep geography of the cosmos, she is a branch torn from her father's own stream: nine parts of Oceanus roll around the earth and the sea, but a tenth part falls away beneath the roots of the world and winds through the dark under the earth as the Styx, flowing beneath towering cliffs in a blackness no sunlight has ever touched. The other rivers of the dead are her kin, the Acheron, the river of woe, the Cocytus, the river of lamentation, and the Pyriphlegethon, the river of fire, but none of them shares her dread honour.

When Zeus rose against his father Cronus and the old order of Titans, he sent word through the gods that all who fought beside him would keep their honours in the new cosmos, and Styx was the very first immortal to answer. On the advice of her own father Oceanus, she gathered her four children and brought them to Mount Olympus, the gods' high fortress. They were a fearsome family to offer: Nike, the winged Victory, Kratos, Strength, Bia, brutal Force, and Zelus, the fire of Rivalry that drives men and gods to compete. Zeus welcomed them with joy and set them beside his throne forever, which is why Victory, Strength, Force and Rivalry never leave the king of heaven to this day. To Styx herself he gave the highest honour in his gift: he made her the Great Oath of the gods. In a universe where even immortals might lie, there would now be one thing that could bind them absolutely, and it was the black water of the underworld's eldest daughter.

The machinery of the oath was as solemn as its power. When the gods swore their deepest vows, as when the goddess Hera swore to the Sleep god Hypnos in the Iliad, Homer's epic of the Trojan War, or when the nymph Calypso swore to the shipwrecked hero Odysseus in the Odyssey, they called upon the inviolable water of the Styx. Zeus sends Iris, the rainbow messenger of the gods, flying with a golden jug to the far cliff where the dread stream leaps from the rock, and she brings back the cold water. The swearing god pours it out and speaks the vow. And if any immortal swears falsely by that water, the punishment is terrible beyond imagining: the forsworn god falls down breathless and voiceless, wrapped in a deathly stupor for a full circle of the year, unable to eat nectar or ambrosia, and when the year has passed, nine more years of exile follow, cut off from every feast and every council of the gods, barred from the laughter of Olympus until the tenth year brings readmission. No threat in heaven carries more weight than those nine silent years.

The strangest chapter of her story is real. In the mountains of Arcadia in the Peloponnese, the mountainous heart of southern Greece, near the village of Nonacris and beneath the snow-capped peak of Mount Chelmos, a thin thread of black water falls down a sheer cliff into a guarded pool, and the Greeks swore that this was the Styx itself, the one place where the underworld river touches the living world. The water was death to drink, and no vessel could hold it: it shattered pottery and glass, corroded bronze and iron, and only a cup made from the hoof of a horse or mule could carry it away. The traveller Pausanias, who wrote a guidebook to Greece in the second century CE, saw the place with his own eyes and recorded the wall built around the pool. The historian Herodotus tells how the Spartan king Cleomenes once made the Arcadians swear loyalty at that dread water. And when Alexander the Great, the conqueror of Persia, died suddenly in Babylon in 323 BCE, one rumour whispered that he had been poisoned with Styx water smuggled out of Arcadia in a mule's hoof, the only cup that could have carried it.

For the dead, the Styx was the border of everything. In the Aeneid, the Roman epic of the hero Aeneas, the river's marsh coils around the underworld nine times, a moat no soul may pass unaided, and on its dark water plies Charon, the sullen ferryman of the dead, who carries souls across for the coin placed in a corpse's mouth. Thetis, the sea nymph mother of Achilles, once gripped her baby by the heel and plunged him into the Styx to arm his body against all wounds, and the one dry spot she held became the fatal heel where an arrow would one day kill him. More than a thousand years later the Italian poet Dante Alighieri found her waiting in his Inferno, where the marsh of Styx forms the fifth circle of Hell, the swamp where the wrathful tear at one another on the surface and the sullen gurgle beneath the mud. From a Titan's daughter to a mountain waterfall to the permanent border of death, no river in human imagination has carried more fear or more honour.