Gaia (earth) arose out of Chaos (chasm, void) already pregnant. Thus, she was "mother earth" from her very birth. The child she delivered was Ouranos/Uranus, the sky. Uranus looked at Gaia and desired her. They became lovers, earth and sky, and Gaia's fertility seemingly knew no bounds. From their union arose lesser giants, monsters, and three groups of beings that would become important to the early history of the gods.
The first of these beings were the elder Cyclopes, not to be confused with the younger race of Cyclopes that would be fathered by Poseidon later in myth. Three in number, their names were Brontes (thunder), Steropes (flasher), and Arges (brightener) and together they represented thunderstorms. In appearance they resembled massive humans but with a single eye set in the center of their forehead. The three brothers were massive, brutal and violent. Though dangerous they were skilled in the art of metal working and were the first blacksmiths.
The second group of beings that Gaia gave birth to were the Hecatonchires (hundred-handed ones). Also three in number, the Hecatonchires were giants possessing a hundred hands and fifty heads. Their names were Briareos (strong), Kottos (strike, to hit), and Gyges (limb or curved) and together they represented hurricanes and typhoons.
The third group of beings that Gaia gave birth to were the Titans. The Titans were six male and six female beings having the appearance of massive humans. The names of the Titans are Hyperion (high one, from above), Iapetus (piercer), Coeus (to question), Crius (ram), Cronus (time), Oceanus (world ocean), Rhea (flowing stream), Theia (goddess), Phoebe (bright), Mnemosyne (memory), Themis (divine law), and Tethys (sea or old woman). The Titans were the first race of gods. They mated with one another and produced a younger generation of Titans. The nature of the Titans was split. Some were brutal and violent while others were more refined.
Now when Gaia gave birth to the Cyclopes Uranus was disturbed by their appearance. He secretly hated his offspring. When Gaia gave birth to the Hecatonchires Uranus was outright horrified. Uranus was so disgusted that he pushed them and the Cyclopes back into the womb of Gaia and imprisoned them there. Little did Uranus know that Gaia was already pregnant with the Titans.
Gaia was in constant agony for having her children trapped within her womb. When she finally could bear no more pain she conceived of a plan. She whispered to her children inside her to make the co-conspirators. Gaia fashioned a sickle or scythe of a magical substance called Adamantium. Adamantium was unbreakable and indestructible. She gave the scythe to her Titan son, Cronus, who was the strongest of her Titan children. She told him that the next time Uranus came to have sex with her to attack him. The time soon came. Uranus came unto Gaia and penetrated her. Together, all of Gaia's trapped children grabbed their father's genitals. Cronus took the scythe and with one swift blow severed his father's scrotum. Uranus screamed in agony and immediately withdrew his member and flew into the heavens, never again to descend unto the earth again.
Meanwhile, the drops of Uranus' blood that fell onto Gaia impregnated her and Gaia soon bore three more groups of beings, the first group being the Giantes, strange offspring that appeared as human beings. Some of the Giantes were massive. Others were human sized. Stranger still, some had snakes instead of legs. The second group was the Erinyes (furies), goddesses of vengeance who appeared as winged hags with snakes for hair. The third and last group were the Meliae, the nymphs of Ash trees.
With Uranus defeated, Gaia gave birth to her Titan offspring first. When it came time for Gaia to birth the Cyclopes and Hecatonchires, Cronus rebelled against his mother, and like his father, imprisoned them deep within Gaia's womb. Gaia was furious. Gaia prophesied that one of Cronus' offspring would overthrow him the same as he had overthrown his father.
The twelve Titans took dominion over the Universe. Cronus, the strongest, became king. Cronus took for his wife his sister Rhea. It wasn't long before Rhea became pregnant. Remembering the words of his mother, Cronus was paranoid about one of his children overthrowing him. Cronus devised a plan. When Rhea gave birth she swaddled the newborn in a blanket and presented her to Cronus with the assumption that he would be pleased. Instead, Cronus snatched the female infant from Rhea's arms and swallowed her. From then on every time Rhea presented a newborn offspring to Cronus he consumed them. A total of five divine offspring had been born only to be eaten by their father. Rhea was despondent. One day while she hid herself in wild nature to weep for her situation, Gaia heard her. Gaia consoled her and whispered to her what she should do the next time she gave birth. When Rhea gave birth again she remembered what Gaia had told her to do. She selected a rock, wrapped it in blankets and presented the disguised rock to Cronus. Just as Gaia predicted, Uranus was none the wiser. He assumed the rock was an infant and promptly swallowed it.
Rhea named the boy Zeus and hid him in a cave on Mt. Ida. Gaia asked a group of minor gods called the Kouretes to protect Zeus from the wrath of Cronus. The Kouretes did this by brandishing their weapons, banging on their shields and screaming, creating such a commotion as to drown out the newborns cries. There Zeus was raised on milk and honey, being nursed by the goat Amalthea.
When Zeus matured, the Titan Metis (cunning, wisdom), gave Zeus a potion that would incapacitate Cronus and cause him to vomit up the offspring he had swallowed. Zeus slipped the potion to Cronus who drunk it and became violently ill. Cronus vomited Zeus' five offspring. Being gods, they could not die even though they had been consumed and were all unharmed. As Cronus writhed on the ground in pain, Zeus freed the Cyclopes and the Hecatonchires from Gaia's womb. Out of appreciation for Zeus freeing them, the Cyclopes gave Zeus lightening bolts which they had forged while trapped inside Gaia.
The gift from the Cyclopes could not have come at a more opportune time. Attracted to the commotion, those Titans and Giantes loyal to Cronus immediately came to his defense. A war called the Titanomachy ensued. The war raged for ten years until Zeus, his siblings, the Cyclopes, the Hecatonchires, and those Titans loyal to Zeus, finally defeated Cronus, the rest of the titans, and the Giantes. Zeus then imprisoned the defeated in the darkest depths of Tartarus as punishment.
Victorious, Zeus and his siblings created their dwelling in Olympos, thus where the given the name Olympians. There, Zeus and his siblings, Hestia, Hera, Demeter, Posiedon, and Hades took dominion of the Universe. Zeus, Poseidon and Hades drew lots as to what realm they would rule. Zeus was awarded the heavens, Poseidon the sea, an Hades the underworld. The earth was deemed neutral ground. The gods mated and produced subsequent generations of deities. Zeus took for his first lover the Titan Metis, the same Titan who had aided him by giving him the potion to give to Cronus. Things seemed to be settled and happy until the day came when the Moirai (the fates) decreed that a a female child born of Metis would be greater than her mother and that a male child born to Metis would be greater than his father. Zeus, fearing that a male offspring conceived with Metis would one day overthrow him, just as he had overthrown Cronus, and just as Cronus had overthrown Uranus, found himself in a predicament. What would Zeus do?