Churning of the Ocean
One day all the gods of India gathered on Mount Meru, the navel of the world, to discuss how they would obtain the amrita elixir of immortality, which lay hidden in the depths of the ocean.
At Vishnu’s suggestion, they decide to churn it, using Vasuki the serpent as a rope and Mount Mandara, resting upon a tortoise, as a churning paddle.
The Deva, the gods benevolent toward humanity, took hold of Vasuki at one end, and the Asura (or anti-gods) took hold at the other. As they pulled, the paddle turned from side to side, churning the ocean, which suddenly turned milky and was transformed into butter.
The gods continued to churn this peculiar mixture and slowly fourteen precious things emerged: among them the sun, the moon, Lakshmi (wife of Vishnu), and finally Dhanvantari, the physician of the gods, bearing the amrita.
The Deva and the Asura both desperately wished to taste it, but Vishnu deceived the Asura so that they could not do so. Only Rahu ("the one who seizes"), a sort of demon, managed to drink a sip. But to prevent him from attaining immortality, Vishnu cut off his head. Nevertheless, he remained immortal and declared war on Soma, the god of the Moon, whom he swallowed and regurgitated several times in an attempt to find more of the elixir of immortality.