Nephele the Phantom of Ixion was born not from a womb but from a god's hand. Ixion, the king of the Lapiths, the most ancient tribe of Thessaly in northern Greece, had committed a crime that should have ended his life. He had murdered his father-in-law, Deioneus or Eioneus, after promising him a bride-price of valuable gifts and then hurling him into a pit of burning coals when the old man came to collect. The murder was treacherous, the violation of guest-friendship absolute, and no city in Greece would shelter Ixion from the pollution that clung to him. He wandered as an outcast until Zeus, the king of the gods, took pity on him and invited him to Mount Olympus to be purified and to dine at the table of the immortals. It was an act of divine mercy that Ixion would repay with the grossest ingratitude in all Greek myth.

On Olympus, Ixion saw Hera, the queen of the gods, the wife of Zeus, the most powerful goddess in the cosmos, and he desired her. His lust was not the casual admiration that mortals felt when they saw a beautiful goddess. It was an obsession, a madness that drove him to plot how he might possess the wife of the god who had saved him. Some accounts say that he boasted to the other guests at the divine feast that he would lie with Hera. Others say that he tried to force himself upon her in a secluded chamber of the palace. In every version, his intention was clear: he would repay Zeus's hospitality by violating his wife.

Zeus was not a god who tolerated such insults. But he was also a god who enjoyed the poetry of punishment, and he devised a revenge that was more cunning than simple death. He took a cloud, a nephos from the sky above Olympus, and he shaped it with his own hands into the perfect likeness of Hera. He gave it her face, her form, her voice, her scent, and her manner of moving. The phantom was so exact that even the other gods, had they not known the trick, might have been deceived. Zeus placed this cloud-woman, this Nephele, in a bedchamber and arranged for Ixion to find her there. Ixion, blind with lust and wine, entered the chamber and lay with the phantom, believing that he was possessing the queen of Olympus herself.

The deception was complete. Ixion fell asleep beside the cloud-woman, and when he woke, Zeus confronted him with the truth. The king of the gods showed him the phantom, still lying in the bed, and revealed that Ixion had not touched Hera but a cloud, a thing of mist and air that had no more substance than a morning fog. The shame was worse than any torture. Ixion, who had thought himself the equal of the gods, was exposed as a man who could not even tell a goddess from a vapor. Zeus bound him to a burning wheel, a wheel of fire that spins eternally through the sky, and Ixion's screams became the sound of thunder in the upper air. He is still spinning, in the Greek telling, and will spin forever, the eternal advertisement of what happens to those who lust after the wives of gods.

But Nephele did not dissolve when her purpose was served. She had taken on something of divine substance in the making, and she was pregnant with Ixion's child. She gave birth to a son named Centaurus, a creature who was not fully human nor fully divine but something in between, a being whose form was never clearly described in the earliest sources but who was associated with the mountains of Thessaly. Centaurus grew to manhood, or to whatever maturity his hybrid nature allowed, and he wandered the slopes of Mount Pelion, the great mountain that rises above the Thessalian plain. There he encountered the wild mares that roamed the mountain's meadows, and from his union with them was born the race of Centaurs, the horse-men who were half-human and half-equine, wild creatures of prodigious strength and violent temperament who would one day fight the Lapiths at the wedding of Pirithous, Ixion's own son, and who would produce the most famous individual Centaur of all, Chiron, the wise teacher of Achilles, Asclepius, and Heracles.

Nephele's role after the birth of Centaurus is not described in the surviving sources. She may have returned to the sky, dissolving back into the clouds from which she was made, or she may have remained on Olympus as a minor deity, a goddess of mist and deception. The Greeks did not worship her with temples or sacrifices, for she was not a goddess of the people but a goddess of the story, a figure who existed to make a point about the consequences of lust and the cunning of divine revenge. But her descendants, the Centaurs, were everywhere in Greek myth. They fought at the wedding of Pirithous, they attacked Heracles, they were defeated by the Lapiths, and they haunted the mountains of Thessaly as symbols of the wildness that civilisation must always hold at bay.