Clymene was born in the earliest days of the cosmos, one of the three thousand Oceanids, the nymph daughters of Oceanus and Tethys, the primordial deities whose waters encircled the world. The Oceanids were not merely spirits of springs and streams; they were the daughters of the greatest water deities in existence, and their marriages connected the old order of the primordial gods to the new generation of Titans and Olympians. Clymene was among the most prominent of these nymphs, and her choice of husband would determine the fate of the world.

She married Iapetus, one of the twelve Titans born to Uranus, the primordial sky-god, and Gaia, the earth goddess. Iapetus was the Titan of mortality, of the west, and of craftsmanship, and his brothers included Cronus, who would castrate Uranus and seize the throne; Oceanus, who remained neutral in the wars that followed; and Hyperion, the father of the sun, moon, and dawn. Clymene and Iapetus had four sons, and each of them would play a decisive role in the mythology of the Greeks. Their names were Atlas, Prometheus, Epimetheus, and Menoetius.

Atlas was the eldest, a giant of immense strength who would later be condemned by Zeus to hold up the broad sky upon his shoulders at the western edge of the world, standing forever as a pillar to keep heaven and earth from collapsing into one another. He was the father of the Hesperides, the nymphs who tended a tree of golden apples in their garden at the far west, and he was tricked by Heracles during the hero's eleventh labour. Prometheus was the second son, the most cunning and the most defiant of the Titans. He sided with Zeus in the Titanomachy, the war between the old Titans and the young Olympian gods that shook the cosmos to its foundations, but he later betrayed the king of the gods by stealing fire from Olympus and giving it to mankind. For this theft, Zeus chained him to a rock in the Caucasus Mountains where an eagle ate his liver each day, and it grew back each night, an eternal torment that lasted until Heracles freed him. Epimetheus was the third son, his name meaning "afterthought," and he was the opposite of his clever brother. When Prometheus told him to wait while he distributed gifts to the animals, Epimetheus gave away every useful quality - strength, speed, wings, claws, thick hides - until there was nothing left for humanity. Prometheus had to steal fire to make up for his brother's mistake. Epimetheus later married Pandora, the first woman, who opened the jar that released every evil into the world. Menoetius was the fourth son, the most arrogant and violent of the brothers. He fought alongside the Titans in the Titanomachy and was struck by Zeus's thunderbolt for his insolence, cast down into Tartarus, the dark pit beneath the earth.

Clymene watched her family destroy itself. Some sources say that she was also called Asia, and that the continent took its name from her, though this is more commonly attributed to her daughter-in-law or granddaughter. In the Theogony of Hesiod, written around 700 BCE, she is simply the Oceanid who married Iapetus and bore the four brothers. In later traditions, she was sometimes conflated with other figures named Clymene, including the wife of Merops and mother of Phaethon, the youth who drove the chariot of the sun and was struck down by Zeus's thunderbolt when he lost control of the horses. But the dominant tradition holds to the Oceanid, the mother of the Titan brothers whose descendants would include the entire human race through Deucalion, the son of Prometheus who survived the great flood.

After the Titanomachy, Clymene disappears from the myths. She is not mentioned in the stories of Prometheus's punishment, nor in the tales of Atlas's burden, nor in the account of Pandora's jar. She simply vanishes, one of the countless maternal figures in Greek myth who give birth to the heroes and then fade into the background. But her blood runs through every story of defiance against the gods. From the fire that Prometheus stole to the jar that Pandora opened, from the heavens that Atlas holds to the thunderbolt that struck Menoetius, every great act of the Titan age began with Clymene's marriage to Iapetus and the four sons she bore him.