According to Greek myth, Prometheus, who had created humans from clay, went against Zeus' will to not give mortals this gift of the gods and be like the gods. He stole fire from Olympus, giving it to man. We know fire did indeed come from above, possibly from the sun's refraction or lightning strike. Fire did distinguish men from the animals, keeping away beast attacks at night, and used for warmth, cooking, and light. 

Rational Hedonism traces its lineage from Greece although similar movements developed in India and China. Therefore the use of Greek mythology and other writings serve as a backdrop for many concepts. One of the most prominent is how man gained the gift of fire.  
Hestia or Estia (Ἑστια which translates as “hearth”), was the sister of Zeus, one of the twelve Olympian deities, and goddess of the hearth and home. Newborn children and those adopted into the family were walked around the hearth as being presented to Hestia. The hearth, her fire, was literally the heart and center of the home, the source of warmth, food, and sacrifices and was not allowed to go out. Later the religious and city temples also had hearth fires, also not allowed to be extinguished without ritual. If soldiers or settlers went to a far-off region to live, they would take fire from a city hearth to bring Hestia's fire from the old home to the new, after a ritual of purification and renewal.