The Nemean Lion was born from monstrous stock. Some say its parents were Typhon, the vast serpentine giant with a hundred dragon heads whom Zeus had struck down with his thunderbolt, and Echidna, the half-woman half-serpent who mothered nearly every monster in Greek myth. Others say it sprang from the moon goddess Selene and fell to earth in a shower of fire. Whatever its origin, the lion grew to a size no mortal beast had ever reached, with claws like scythes and a hide so thick and hard that no weapon forged by human hands could pierce it. It settled in a cave with two mouths on the slopes of Mount Tretus near the city of Nemea in the Argolid, the region of the Peloponnese that was home to the great Bronze Age palace-culture. There it preyed upon the cattle and the people, and the men of Nemea grew so terrified that they dared not leave their walls.

Heracles came to Nemea in the service of Eurystheus, the king of Tiryns and Mycenae who had been assigned the task of commanding the hero by the oracle of Apollo at Delphi. Heracles had been driven mad by Hera, the queen of Olympus and wife of Zeus, who hated him because he was the son of her husband and the mortal woman Alcmene. In his madness Heracles had killed his own wife Megara and their children, and when he recovered his senses he went to Delphi to ask how he could atone. The Pythia, the priestess who spoke Apollo's prophecies in riddles, told him that he must serve Eurystheus for twelve years and perform whatever labors the king demanded. The first of these labors was to bring back the skin of the Nemean Lion.

Heracles travelled to Nemea and found the lion's cave. He shot arrows at it, but the shafts bounced off the hide like twigs against stone. He struck it with his great olive-wood club, but the blows only angered the beast without wounding it. The lion charged, and Heracles, seeing that no weapon would avail him, dropped his club and grappled with the monster bare-handed. The fight was terrible, for the lion's claws could tear bronze and its jaws could crush a bull's skull. But Heracles was stronger. He wrapped his arms around the lion's neck and squeezed, his muscles straining until the beast's eyes bulged and its tongue lolled and at last its body went limp. He had killed the unkillable with nothing but his own hands.

But the pelt remained. Heracles tried to skin the lion with his knife, but the blade bent and broke against the hide. He tried with a sharpened stone, and the stone shattered. Then he had an idea. He took one of the lion's own claws, the curved talons that had torn through bronze and bone, and used them to cut the hide from the carcass. The claw sliced through where no other edge could, and Heracles peeled the golden skin away in one piece. He cut slits for his arms and draped the pelt over his shoulders like a cloak, pulling the lion's head up over his own so that the empty eyes stared out above his brow and the fanged jaws framed his face. From that day forward he wore the Nemean Lion's Pelt in every battle, every labor, and every trial, and no enemy who saw him coming in that terrible disguise ever faced him without fear.

The pelt appears again in the story of Heracles' second labor, the Lernaean Hydra, the many-headed serpent that lived in the marshes of Lerna near Argos. Heracles wore the lion skin as armour when he confronted the Hydra, and when the serpent's venomous fangs struck at him, they could not pierce the hide that had already turned aside every weapon in Greece. His nephew Iolaus, who had come to aid him, burned the stumps of the Hydra's severed heads to keep them from growing back, and together they destroyed the beast. But the Hydra's blood was poison, and Heracles dipped his arrows in it, so that from that day forward even his shafts carried death. The pelt had saved him once, and it would save him again through every labor that followed, from the Erymanthian Boar to the Cretan Bull to the apples of the Hesperides.

In later ages, the pelt became the single most recognisable attribute of Heracles. Greek sculptors from the archaic period onward showed him with the lion's head as a helmet and the fur draped across his back, and the image was so fixed that a Heracles without his pelt was almost unthinkable. Roman emperors struck coins showing the hero in the lion skin to symbolise their own strength and invincibility. The pelt passed into the medieval imagination as the armour of the Christian strongman, and Renaissance painters placed it on the shoulders of every Hercules they depicted. In the modern world, the lion skin remains the symbol of conquest over the unconquerable, the proof that what cannot be pierced can still be overcome by strength and cunning.