In Greek mythology, the Greek god Atlas was one of the Titans - an ancient cast of gods and goddesses who ruled the Universe before the more recent Olympic gods and goddesses took control. In fact it was Atlas who led the charge as the Titans fought the Olympic Gods for control of the Universe and lost. Atlas and his brother Menoetius fought on the side of the Titans while their other brothers Prometheus and Epimetheus took the side of the Olympians. After the Titan’s defeat at the hands of Zeus and company, Atlas was punished by being forced to stand on the western edge of the world (Gaia) and hold up the weight of the heavens (Uranus) on his shoulders.
Modern interpretations often depict Atlas holding the Earth on his shoulders. This is a common misconception and is likely confusing because we often think of the enduring symbol of Atlas synonymously with the idea of “carrying the weight of the world” on one’s back.
As a Greek god Atlas naturally had a specialty that he taught to the other gods and some humans. Before the weight of the heavens rested on his shoulders Atlas was, fittingly, a god of astronomy. Because humans used this knowledge to improve navigation, agriculture, and a general understanding of the stars, Atlas was a figure of great importance. As his students watched the stars move across the sky they also assumed that it was great and mighty Atlas who must cause the stars to rotate across the sky.
Atlas tried to ease his burden when he met Hercules during the hero’s Twelve Labors. According to Greek mythology Atlas was asked by Hercules for help completing one of his tasks - taking apples from the tree in the Garden of the Hesperides. The tree was famously guarded by the great python Ladon the Dragon. The garden itself was tended to by none other than Atlas’s own daughters, the Hesperides. Therefore Hercules suggested that Atlas go to the garden for him and fetch the apples from his daughters, thus avoiding dealing with Ladon. In exchange Hercules would hold up the heavens for Atlas while he was gone.
According to Greek mythology Atlas retrieved the apples for Hercules then had an idea - he suggested to the young hero that he deliver the apples himself. In the mind of Atlas, he could leave Hercules there with the burden of carrying the sky and make a clean break. Hercules sensed that a trick was behind the offer so he agreed as long as Atlas could hold up the sky again while he fixed his cloak around his shoulders (to ease the burden). Atlas agreed and took the sky back only to watch Hercules grab the apples and run away.
There is another myth, though, that suggests that Hercules had his conscious get the better of him and so he built two pillars near Atlas that held up the sky for him, giving the much maligned titan the rest he deserved.