Uranus, the Greek God and father of the Titans, symbolized the sky.
In the Ancient Greek creation story, Uranus came every night to cover the earth and mate with Gaea, but he hated the children she bore him. Their first six sons and six daughters became the Titans, the three one-hundred-handed giants became the Hekatonkheires, and the one-eyed giants became the Cyclopes.
Uranus imprisoned Gaea's youngest children in Tartarus, deep within Earth, where they caused pain to Gaia. She shaped a great flint-bladed sickle and asked her sons to castrate Uranus. Only Cronus, the youngest and most ambitious of the Titans, was willing: he ambushed his father and castrated him, casting the severed testicles into the sea.
From the blood that spilled from Uranus onto the Earth came forth the Giants, the Erinyes, the Meliae, and, from the genitals that fell into the sea, Aphrodite.
After Uranus was replaced, Cronus re-imprisoned the Hekatonkheires and Cyclopes in Tartarus. Uranus and Gaea then prophesied that Cronus, in turn, was destined to be overthrown by his own son, and so the Titan attempted to avoid this fate by devouring his young. Zeus, through deception by his mother Rhea, avoided this fate. He fulfilled the prophecy of Uranus and Gaea when he overthrew Cronus and imprisoned the Titans.