The scheme above is mainly based on Hesiod's Theogony, an epic poem written in the 7th century BC describing the origin of the world and the genealogies of greek gods and heroes.
Once upon a time was the CHAOS from which came GEA (the earth), TARTARO (the abyss), URANO (the sky) and EROS (love). Eros pushed Gea and Urano to stay together and generate the Stars, the Seas and the Mountains, then Ocean and the Rivers. Between their children were Chronos and Rea who generated Zeus, father of all gods..