In the beginning Nyx, who is Night, hovered in the darkness. An egg was laid by Nyx, the black-winged bird. From the upper shell of that egg was formed Ouranos, who is Heaven, and from the lower shell, Gaia, who is Earth. And Eros, who is Love, flew forth from the egg. Drawn together by Eros, Ouranos and Gaia married, and eventually Gaia gave birth to their first children: the Cyclopes Brontes, Arges, and Steropes.
Ouranos was horrified by the ugly children, who had only one eye each. They were unsightly in his opinion and he wanted them gone. But he couldn't kill them, because they were immortal and threw them into Tartarus, the darkest and deepest abyss of the Underworld, with the monster Kampê to guard them.
The same was done to Gaia's next batch of children, the three Hekatonkheires Briares, Cottus, and Gyges, each with hundred arms and fifty faces. This caused Gaea great pain and grief. She was also furious because they were her children, and because Ouranos cared nothing for them. She asked her children, the Titans, to get rid of Ouranos so she could save the Cyclopes and the Hekatonkhires. Only her youngest son Kronos was brave enough to do it. With his four brothers Hyperion, Krios, Iapetus and Koios, Kronos crept into Ouranos' room as he lay with Gaia, and having his four brothers hold im at the east, south, west and north corners respectively, castrated him with a flint sickle from Gaia.
The pieces of Ouranos fell onto the Earth, where his blood fertilized the pit of Tartarus (later giving rise to the Gigantes). From his parts rose the Erinyes (the avenging Furies), the Meliae (the ash-tree nymphs), and, according to some, the Telkhines. From the genitals in the sea came forth Aphrodite.
While he died, Ouranos cursed Kronos, "What you have done to me," he said, "the same shall be done to you, by your son."